Increase and plateau of CD4 T-cell counts in the 3(1/2) years after initiation of potent antiretroviral therapy

Establishment and evaluation of a predictive model for immune reconstitution in people living with HIV after antiretroviral therapy

BACKGROUND

Achieving complete immune reconstitution (CIR) in people living with human immunodeficiency virus (PLWH) following antiretroviral therapy (ART) is essential for preventing acquired immunodeficiency syndrome (AIDS) progression and improving survival. However, there is a paucity of robust prediction models for determining the likelihood of CIR in PLWH after ART. We aimed to develop and validate a CIR prediction model utilizing baseline data.

METHODS

Baseline data including demographic information, immunological profiles, and routine laboratory test results, were collected from PLWH in Yunnan, China. Baseline referred to the first recorded results after HIV diagnosis but before initiating ART, and these initial measurements served as the baseline data for analysis. The participants were divided into training and validation sets (7:3 ratio). To construct the model and accompanying nomogram, univariable and multivariable Cox regression analyses were performed. The model was evaluated using the C-index, time-dependent receiver operating characteristic (ROC) curves, calibration curves, and clinical decision curves to assess discrimination, calibration, and clinical applicability.

RESULTS

Five thousand four hundred eight PLWH were included, with a CIR of 38.52%. Cox regression analysis revealed various independent factors associated with CIR, including infection route, baseline CD4+T cell count, baseline CD4/CD8 ratio, interval from HIV diagnosis to ART initiation, and the level of PLT, Glu, Crea, HGB, ALT. A nomogram was formulated to predict the probability of achieving CIR at years 4, 5, and 6. The model demonstrated good performance, as evidenced by an AUC of 0.8 for both sets. Calibration curve analysis demonstrated a high level of agreement, and decision curve analysis revealed a significant positive yield.

CONCLUSIONS

This study successfully developed a prediction model with robust performance. This model has considerable potential to aid clinicians in tailoring treatment strategies, which could enhance outcomes and quality of life for PLWH.

The prognosis for delayed immune recovery in HIV-infected children might be associated with pre-cART CD4+ T cell count irrespective of co-infection with tuberculosis

BACKGROUND

Immune reconstitution following the initiation of combination antiretroviral therapy (cART) significantly impacts the prognosis of individuals infected with human immunodeficiency virus (HIV). Our previous studies have indicated that the baseline CD4+ T cells count and percentage before cART initiation are predictors of immune recovery in TB-negative children infected with HIV, with TB co-infection potentially causing a delay in immune recovery. However, it remains unclear whether these predictors consistently impact immune reconstitution during long-term intensive cART treatment in TB-negative/positive children infected with HIV.

RESULTS

We confirmed that the baseline CD4+ T cell count is a significant predictor of immune recovery following long-term intensive cART treatment among children aged 0 to 13 years. Children with lower CD4+ T cell count prior cART initiation did not show substantial immunological recovery during the follow-up period. Interestingly, children who were co-infected with TB and had higher baseline CD4+ T cell count eventually achieved good immunological recovery comparable to the TB-negative HIV-infected children. Hence, the baseline CD4+ T cell count at the onset of treatment serves as a reliable predictor of immunological reconstitution in HIV-infected children with or without TB co-infection. Taken together, this follow-up study validates our previous findings and further establishes that initiating cART early alongside early HIV testing can help prevent the diminished CD4+ T cell count associated with inadequate immunological reconstitution.

The interplay of COVID-19 and HIV: A comprehensive review of clinical outcomes and demographic associations

AIM

The COVID-19 pandemic posed unprecedented challenges to global healthcare, particularly affecting respiratory systems and impacting individuals with pre-existing conditions, including those with HIV.

METHOD

HIV's impact on clinical outcomes was assessed in four Statistical Population, synchronized with control groups. The study also explored the influence of SARS-CoV-2 and COVID-19 treatments. Ultimately, a comparison was drawn between patients with and without HIV.

RESULTS

In the first Statistical Population of COVID-19 patients with HIV, predominantly African-American men with risk factors such as obesity, hypertension, and diabetes were present. Diagnostic results showed no significant differences between the two groups. In the second Statistical Population, half of the patients were asymptomatic, with diagnoses mostly based on clinical symptoms; 6 individuals developed severe respiratory illness. In the third Statistical Population, 81 % of patients were treated at home, and all hospitalized patients had CD4+ lymphocyte counts above 350 cells/mm³. Most patients improved, with fatalities attributed to comorbid conditions. In the fourth Statistical Population, HIV patients were less likely to benefit from antimicrobial drugs, and mortality was higher, though synchronized analysis did not reveal significant differences.

CONCLUSION

HIV patients are more susceptible to COVID-19, but the direct impact is less significant than other factors. Additional factors contribute to increased risk, while early improvement, accurate diagnosis, and intensive care reduce fatalities.

The Prognosis for Delayed Immune Recovery in HIV-Infected Children might be Associated with Pre-cART CD4 + T cell Count Irrespective of Co-Infection with Tuberculosis

Background

Immune reconstitution following the initiation of combination antiretroviral therapy (cART) significantly impacts the prognosis of individuals infected with human immunodeficiency virus (HIV). Our previous studies have indicated that the baseline CD4+ T cells count and percentage before cART initiation are predictors of immune recovery in TB-negative children infected with HIV, with TB co-infection potentially causing a delay in immune recovery. However, it remains unclear whether these predictors consistently impact immune reconstitution during long-term intensive cART treatment in TB-negative/positive children infected with HIV.

Results

We confirmed that the baseline CD4+ T cell count is a significant predictor of immune recovery following long-term intensive cART treatment among children aged 5 to 18 years. Children with lower CD4+ T cell count prior cART initiation did not show substantial immunological recovery during the follow-up period. Interestingly, children who were co-infected with TB and had higher baseline CD4+ T cell count eventually achieved good immunological recovery comparable to the TB-negative HIV-infected children. Hence, the baseline CD4+ T cell count at the onset of treatment serves as a reliable predictor of immunological reconstitution in HIV-infected children with or without TB co-infection. Taken together, this follow-up study validates our previous findings and further establishes that initiating cART early alongside early HIV testing can help prevent the diminished CD4+ T cell count associated with inadequate immunological reconstitution.

Immune recovery among Romanian HIV/AIDS patients receiving darunavir/ritonavir or darunavir/cobicistat regimens in cART management: A three-year study

Approximately two-thirds of Romanian HIV patients were parenterally infected with the F subtype of HIV in early childhood. They are now in the context of immunological aging, with immunosuppression posing an additional challenge in developing the most effective and well-tolerated regimens. The risk of an improper immune recovery is higher in these patients than in newly diagnosed patients. The primary goal of this retrospective study was to conduct a comparative analysis of the immune recovery, measured at three time points, on 462 HIV-infected patients who were registered at the "Matei Balş National Institute of Infectious Diseases", Bucharest, Romania, between 2018 and 2021, as follows: darunavir (DRV) 600 mg plus ritonavir (RTV) 100 mg (twice daily) was given to 384 patients, while DRV 800 mg plus cobicistat (COBI) 150 mg was given to 78 patients (once daily). The immune response was assessed by counting T lymphocytes, CD4 count cells/mm³, and the CD4/CD8 lymphocyte count ratio. Additionally, the study assessed the relationship between the immune and virological responses to therapy. Using various statistical tests, the results revealed that the immune response is normal in both groups, but with a statistically significant difference (p < 0.05) for the DRV/c group. Statistical associations between RNA viral plasma load and immune response (CD4 count and CD4/CD8 ratio) were assessed at all three visits and showed an insignificant association for the first two time points; however, at the final visit, the outcomes changed and reached statistical significance for both groups.

Effect of Traditional Chinese Medicine Therapy on the Trend in CD4+ T-Cell Counts among Patients with HIV/AIDS Treated with Antiretroviral Therapy: A Retrospective Cohort Study

This retrospective cohort study was conducted to explore the effect of traditional Chinese medicine (TCM) therapy on the long-term trends in CD4⁺ T-cell count among patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) who were treated with combined antiretroviral therapy (cART) over a 14-year period. A total of 721 individuals were treated with cART alone (cART group), and 307 individuals were treated with both cART and TCM (TCM + cART group). Among all enrolled patients with HIV/AIDS, 99.5% were farmers, 71.1% had more than 6 years of education, and 96.8% were infected with HIV via a paid blood donation. For those patients with HIV/AIDS who had a baseline CD4⁺ T-cell count of <350 cells/mL, the CD4⁺ T-cell count tended to increase to approximately 350 cells/mL more rapidly in the TCM + cART group than in the cART group, but when the baseline CD4⁺ T-cell count was ≥350 cells/mL, there was no difference between the cART and TCM + cART groups. For other patients with HIV/AIDS who had a baseline CD4⁺ T-cell count of 350–500 cells/mL, the CD4⁺ T-cell counts tended to increase slightly, but there was no difference between the two groups. For patients with HIV/AIDS who had a baseline CD4⁺ T-cell count of ≥500 cells/mL, the CD4⁺ T-cell counts tended to be maintained at a particular level, with no difference between the two groups. The results show that the effect of TCM on the CD4⁺ T-cell counts of patients with HIV/AIDS is related to the CD4⁺ T-cell level at the time of initial treatment. TCM can increase the CD4⁺ T-cell count among patients with HIV/AIDS who have a baseline CD4⁺ T-cell count of <350 cells/mL. Sex and age have a slight influence on the therapeutic effect of TCM.

CD4/CD8 ratio improvement in HIV-1-infected patients receiving dual antiretroviral treatment

The CD4/CD8 ratio is an indirect marker of immune activation, immune senescence, and inflammation in HIV infection. We performed a prospective study of the CD4/CD8 ratio evolution in 245 virally-suppressed (median, 55 months) HIV-infected patients (29% females) who had switched to four dual antiretroviral regimens. At baseline, the median CD4/CD8 ratio was 0.71 (interquartile range, IQR, 0.46-0.97), associated with duration of HIV infection, nadir CD4+ cell count, and AIDS diagnosis. It was lower in the case of hepatitis C virus coinfection and cardiovascular disease (p = 0.09), but the ratio was higher in patients with chronic kidney disease, proteinuria, or osteoporosis. At 48 weeks, the median CD4/CD8 ratio increased by 3% (+0.02; IQR, -0.07, +0.09; p = 0.07); greater improvement was observed in patients with lower baseline ratios and previous AIDS diagnosis. The slope of increase was slower in patients with the highest baseline values. Also, there were no differences in the CD4/CD8 ratio increase according to type of dual regimen, after adjusting for baseline and HIV-related values. In conclusion, CD4/CD8 ratio increase is observed during suppressive dual regimens, and its extent is related to baseline values and previous HIV-related factors. Longer duration on antiretroviral therapy and drug toxicity could affect the evolution of this marker in the presence of comorbidities.

Prediction of Liver Disease, AIDS, and Mortality Based on Discordant Absolute and Relative Peripheral CD4 T Lymphocytes in HIV/Hepatitis C Virus-Coinfected Individuals

Hepatitis C virus (HCV)-induced liver fibrosis and splenomegaly may lead to discordance between absolute numbers and percentages of lymphocytes and subpopulations because of sequestration. We investigated lymphocyte discordance in HIV/HCV-coinfected individuals and its relationship to progression to liver disease, AIDS, and all-cause mortality. This is an observational retrospective cohort study. Adjusted hazard ratios (aHRs) with 95% confidence intervals (95% CIs) associated with liver disease, AIDS, or mortality were computed by time-updated Cox proportional hazards regression. Of 380 HIV/HCV-coinfected adult individuals followed for a median of 8.2 years, 360 individuals had a median of 11 discordant measurements corresponding to 5,080 of 9,091 paired samples (56%). Discordance alone was not associated with any of the outcomes. By multivariable analysis, a doubling of absolute or percentage CD4 cells was associated with comparable lower risks of mortality (aHR: 0.60, 95% CI: 0.53-0.67, p < .0001 and aHR: 0.67, 95% CI: 0.56-0.79, p < .0001, respectively). Higher CD4/CD8 ratio was associated with a lower mortality risk (aHR: 0.39, 95% CI: 0.22-0.71 per doubling, p = .002). Only absolute CD4 cell measurements predicted AIDS. Development of liver disease was not predicted by total lymphocyte count or subpopulations. Despite a high prevalence of lymphocyte-subpopulation discordance with HIV/HCV coinfection, absolute CD4 cell count predicted mortality and AIDS, whereas CD4 percentage only predicted mortality. Neither CD4 T lymphocyte count nor CD4 percentage was associated with liver disease in this cohort. These findings may be necessary and useful in countries where antiretroviral treatment is not initiated for all HIV-infected individuals.

Vitamin D status and immune function reconstitution in HIV-infected men initiating therapy

OBJECTIVE

Despite effective antiretroviral therapy (HAART) and durable viral suppression, many HIV-infected individuals still do not achieve CD4 cell count (CD4) normalization. Vitamin D has immunoregulatory functions, including inducing the development of T cells and higher levels may improve CD4 rebound.

DESIGN

Longitudinal study of men from the Multicenter AIDS Cohort Study who virally suppressed following HAART initiation and had pre-HAART and post-HAART 25(OH)D and 1,25(OH)2D measurements and repeated measures of CD4.

METHODS

CD4 rebound was modeled using a nonlinear mixed effects model. We estimated the adjusted effect (adjusted for pre-HAART antiretroviral exposure, black race, age and CD4 at HAART initiation) of pre-HAART and post-HAART vitamin D metabolite levels on the rate of CD4 increase and final CD4 plateau.

RESULTS

Among the 263 HIV-infected HAART initiators with pre-HAART vitamin D measurements, a 1-SD higher pre-HAART 25(OH)2D level was associated with a 9% faster rate of rise (P = 0.02) but no gain in final CD4 plateau. In contrast, a 1-SD higher 1,25(OH)2D level was associated with a 43-cell lower final CD4 (P = 0.04). Among 560 men with post-HAART measurements, findings were similar to those for pre-HAART 25(OH)2D with 1-SD higher level associated with faster rate of rise but no improvement in final CD4.

CONCLUSION

We found no evidence that higher vitamin D metabolite levels pre-HAART or post-HAART are associated with better CD4 outcomes among HIV-infected HAART initiators. However, the value of pre-HAART 1,25(OH)2D levels as an indicator of immune response dysregulation could be further explored.

Immunological recovery in tuberculosis/HIV co-infected patients on antiretroviral therapy: implication for tuberculosis preventive therapy

BACKGROUND

Understanding the immune response to combination antiretroviral therapy (cART) is essential for a clear approach to tuberculosis (TB) preventive therapy. We investigated the immunological recovery in cART-treated HIV-infected patients developing TB compared to those who remained free of TB.

METHODS

We extracted data of HIV-infected patients from a multicenter cohort for the HIV clinical surveillance in Germany. No patients included in our study had TB at the beginning of the observation. Using a longitudinal mixed model, we assessed the differences in the mean change of biomarkers (CD4+ cell count, CD8+ cell count, CD4:CD8 ratio and viral load) since cART initiation in patients who remained free of TB vs. those developing TB. To detect the best-fit trajectories of the immunological biomarkers, we applied a multivariable fractional polynomials model.

RESULTS

We analyzed a total of 10,671 HIV-infected patients including 139 patients who developed TB during follow-up. The highest TB incidences were observed during the first two years since cART initiation (0.32 and 0.50 per 100 person-years). In an adjusted multivariable mixed model, we found that the average change in CD4+ cell count recovery was significantly greater by 33 cells/μl in patients who remained free of TB compared with those developing TB. After the initial three months of cART, 65.6% of patients who remaining free of TB achieved CD4+ count of ≥400 cells/μl, while only 11.3% of patients developing TB reached this immunological status after the three months of cART. We found no differences in the average change of CD8+ cell count, CD4:CD8 ratio or viral load between the two-patient groups.

CONCLUSION

All HIV-infected patients responded to cART. However, patients developing TB showed reduced recovery in CD4+ cell count and this might partly explain the incident TB in HIV-infected patients receiving cART. These findings reinforce the importance of adjunctive TB preventive therapy for patients with reduced recovery in CD4+ cell count.

Hierarchical mixture models for longitudinal immunologic data with heterogeneity, non-normality, and missingness

It is a common practice to analyze longitudinal data frequently arisen in medical studies using various mixed-effects models in the literature. However, the following issues may standout in longitudinal data analysis: (i) In clinical practice, the profile of each subject's response from a longitudinal study may follow a "broken stick" like trajectory, indicating multiple phases of increase, decline and/or stable in response. Such multiple phases (with changepoints) may be an important indicator to help quantify treatment effect and improve management of patient care. To estimate changepoints, the various mixed-effects models become a challenge due to complicated structures of model formulations; (ii) an assumption of homogeneous population for models may be unrealistically obscuring important features of between-subject and within-subject variations; (iii) normality assumption for model errors may not always give robust and reliable results, in particular, if the data exhibit non-normality; and (iv) the response may be missing and the missingness may be non-ignorable. In the literature, there has been considerable interest in accommodating heterogeneity, non-normality or missingness in such models. However, there has been relatively little work concerning all of these features simultaneously. There is a need to fill up this gap as longitudinal data do often have these characteristics. In this article, our objectives are to study simultaneous impact of these data features by developing a Bayesian mixture modeling approach-based Finite Mixture of Changepoint (piecewise) Mixed-Effects (FMCME) models with skew distributions, allowing estimates of both model parameters and class membership probabilities at population and individual levels. Simulation studies are conducted to assess the performance of the proposed method, and an AIDS clinical data example is analyzed to demonstrate the proposed methodologies and to compare modeling results of potential mixture models under different scenarios.

Food insecurity and low CD4 count among HIV-infected people: a systematic review and meta-analysis

Food insecurity is defined as a limited or uncertain ability to acquire acceptable foods in socially acceptable ways, or limited or uncertain availability of nutritionally adequate and safe foods. While effective antiretroviral treatment can significantly increase CD4 counts in the majority of patients, there are certain populations who remain at relatively low CD4 count levels. Factors possibly associated with poor CD4 recovery have been extensively studied, but the association between food insecurity and low CD4 count is inconsistent in the literature. The objective is to systematically review published literature to determine the association between food insecurity and CD4 count among HIV-infected people. PubMed, Web of Science, ProQuest ABI/INFORM Complete, Ovid Medline and EMBASE Classic, plus bibliographies of relevant studies were systematically searched up to May 2015, where the earliest database coverage started from 1900. Studies that quantitatively assessed the association between food insecurity and CD4 count among HIV-infected people were eligible for inclusion. Study results were summarized using random effects model. A total of 2093 articles were identified through electronic database search and manual bibliographic search, of which 8 studies included in this meta-analysis. Food insecure people had 1.32 times greater odds of having lower CD4 counts compared to food secure people (OR = 1.32, 95% CI: 1.15-1.53) and food insecure people had on average 91 fewer CD4 cells/µl compared to their food secure counterparts (mean difference = -91.09, 95% CI: -156.16, -26.02). Food insecurity could be a potential barrier to immune recovery as measured by CD4 counts among HIV-infected people.

Single Tablet Regimen Usage and Efficacy in the Treatment of HIV Infection in Australia

Single tablet regimens (STRs) for HIV infection improve patient satisfaction, quality of life, medication adherence, and virological suppression compared to multitablet regimens (MTRs). This is the first study assessing STR uptake and durability in Australia. This retrospective audit of all patients receiving an STR (n = 299) at a large Sydney HIV clinic (January 2012–December 2013) assessed patient demographics, treatment prior to STR, HIV RNA load and CD4 during MTR and STR dosing, and reasons for STR switch. 206 patients switched from previous antiretroviral treatment to an STR, of which 88% switched from an MTR. Reasons for switching included desire to simplify treatment (57%), reduced side effects or toxicity (18%), and cost-saving for the patient. There was no switching for virological failure. Compared to when on an MTR, patients switching to an STR had significantly lower HIV RNA counts (p < 0.001) and significantly higher CD4 counts (p < 0.001). The discontinuation rate from STR was very low and all patients who switched to an STR maintained virological suppression throughout the study duration, although the study is limited by the absence of a control group.

Three different patterns of CD4 recovery in a cohort of Chinese HIV patients following antiretroviral therapy - a five-year observational study

To explore the heterogeneity of CD4 responses following highly active antiretroviral therapy, the patterns of CD4 recovery of HIV-1-infected Chinese patients who have been on their first antiretroviral regimen for ≥5 years were analysed. The CD4 trajectories were traced, smoothed and differentiated into three defined profiles. Half (56.3%) were 'satisfactory responders', with CD4 gain of >100 cells/μL and a peak of >350 cells/μL, plateauing before the end of Year 5. Thirty-three (24.4%) were 'continuing responders' whose CD4 rise persisted at Year 4-5. The remaining 26 (19.3%) were 'poor responders'. Presentation with AIDS before therapy was common not just among 'poor' but also paradoxically the 'continuing' responders. While a majority had responded well to antiretroviral therapy, older patients and those with AIDS diagnosis before initiation of therapy may never achieve a satisfactory level even with effective treatment. Categorization of HIV patients by their CD4 trajectory may support the prediction of immunological outcome over time, and ultimately inform treatment choices.

Cost effectiveness of darunavir/ritonavir combination antiretroviral therapy for treatment-naive adults with HIV-1 infection in Canada

OBJECTIVE

The AntiRetroviral Therapy with TMC114 ExaMined In naive Subjects (ARTEMIS) clinical trial examined the efficacy and safety of two ritonavir-boosted protease inhibitors (PI/r), darunavir/r 800/100 mg once daily (QD) and lopinavir/r 800/200 mg daily, both used in combination with tenofovir disoproxil fumarate/emtricitabine. This study aimed to assess the cost effectiveness of the darunavir/r regimen compared with the lopinavir/r regimen in treatment-naive adults with HIV-1 infection in Canada.

METHODS

A Markov model with a 3-month cycle time and six CD4 cell-count-based health states (>500, 351-500, 201-500, 101-200, 51-100, and 0-50 cells/mm(3)) followed a cohort of treatment-naive adults with HIV-1 infection through initial darunavir/r or lopinavir/r combination therapy and a common set of subsequent regimens over the course of their remaining lifetimes. Population characteristics and transition probabilities were estimated from the ARTEMIS clinical trial and other trials. Costs (in 2014 Canadian dollars), utilities, and mortality were estimated from Canadian sources and published literature. Costs and health outcomes were discounted at 5% per year. One-way and probabilistic sensitivity analyses were performed, including a simple indirect comparison of the darunavir/r initial regimen with an atazanavir/r-based regimen.

RESULTS

In the base-case lifetime analysis, individuals receiving initial therapy with the darunavir/r regimen experienced 0.25 more quality-adjusted life-years (QALYs) with lower antiretroviral drug costs (-$14,246) and total costs (-$18,402) than individuals receiving the lopinavir/r regimen, indicating that darunavir/r dominated lopinavir/r. In an indirect comparison with an atazanavir/r-based regimen, the darunavir/r regimen remained the dominant choice, but with lower cost savings (-$2,303) and QALY gains (0.02). Results were robust to a wide range of other changes in input parameter values, population characteristics, and modeling assumptions. The probabilistic sensitivity analysis demonstrated that the darunavir/r regimen was cost effective compared with the lopinavir/r regimen in over 86% of simulations for willingness-to-pay thresholds between $0 and $100,000 per QALY gained.

CONCLUSIONS

Darunavir/r 800/100 mg QD may be a cost-effective PI/r component of initial antiretroviral therapy for treatment-naive adults with HIV-1 infection in Canada.

Among patients with sustained viral suppression in a resource-limited setting, CD4 gains are continuous although gender-based differences occur

INTRODUCTION

There is conflicting data on long-term CD4 immune recovery after combination antiretroviral therapy (ART) in resource-limited settings. Virologic suppression is rarely documented in cohorts from sub-Saharan Africa so objective evidence of adherence is biologically unsubstantiated. We sought to investigate long-term patterns of immune recovery in Ugandan patients on ART with sustained viral suppression.

METHODS

A prospective cohort of patients starting ART between April, 2004 and April, 2005 at the Infectious Diseases Institute with sustained viral suppression (viral load ≤ 400 copies/ml at month 6 and 12) while on first-line ART. Propensity scores were used to adjust for treatment allocation (nevirapine or efavirenz) at ART initiation. Data were analyzed using Kaplan Meier methods and cross-sectional time series regression.

RESULTS

Three hundred and fifty-six patients were included in the analysis.71.6% were female, 87% in WHO stage 3 or 4, median age was 37 years, (IQR:32-43), and median CD4 count was 108 cells/µL, (IQR:35-174) at ART start. At multivariable analysis, lower immune recovery (measured by change in CD4 from ART start at each time interval) was associated with male-gender (-59, 95% CI: 90, -28, P<0.001), baseline CD4 count of 101-200 cells/µL (-35, 95% CI: 62, -9, P=0.009) and >200 (-64, 95% CI: 101, -26, P=0.001), and use of AZT at baseline (-47, 95% CI: -74, -20, P=0.001). Median time to reach >400 cells/µL was longer in males (197.4 weeks, IQR:119.9-312.0), compared to females (144.7 weeks, IQR:96.6-219.7, P<0.001). The cumulative probability of attaining CD4 >400 cells/µL over 7 years was higher in females compared to males (P<0.001).

CONCLUSIONS

There was long-term, continuous, immunologic recovery up to 7 years after ART initiation in an urban Ugandan cohort. Virologically suppressed women had better sustained immune recovery than men. Men take longer to immune reconstitute and have a lower probability of reaching a CD4 cell count >400 cells/µL. The biologic mechanisms of these gender differences need further exploration.

CD4(+) T-cell recovery after initiation of antiretroviral therapy in a resource-limited setting: a prospective cohort analysis

BACKGROUND

CD4(+) T-cell count recovery after antiretroviral therapy (ART) initiation is associated with improved health outcomes. It is unknown how the CD4(+) T-cell counts of African HIV patients recover following ART initiation.

METHODS

We examined CD4(+) T-cell count recovery in a large cohort of HIV-positive patients initiating ART in Uganda between 2004 and 2011. We categorized patients according to their CD4(+) T-cell count at ART initiation. All patients received CD4(+) T-cell count evaluations on a biannual basis. We used quantile regression to model the recovery of CD4(+) T-cells during ART.

RESULTS

A total of 5,271 patients aged ≥14 years at baseline were included. The median number of CD4(+) T-cell count measurements was 6 (IQR 4-8), and vital status at censoring was known in 97.2% of individuals. Most CD4(+) T-cell count recovery occurred within the first 12 months, with marginal increases beyond 18 months and stabilization after 5 years. The strongest predictor of CD4(+) T-cell count recovery was baseline CD4(+) T-cell count. After 5 years on treatment, the median CD4(+) T-cell count was 334 cells/mm(3) for patients initiating ART with <100 cells/mm(3). Only those initiating ART with >200 cells/mm(3) reached a 5-year median >500 cells/mm(3). Adolescents had the most robust CD4(+) T-cell count recovery with a median increase after 12 months that was 109 cells/mm(3) greater than those initiating ART at age ≥50 years.

CONCLUSIONS

In individuals from a resource-limited setting, baseline CD4(+) T-cell count was highly predictive of the maximum CD4(+) T-cell count level achieved while on ART.

An information criterion for marginal structural models

Marginal structural models were developed as a semiparametric alternative to the G-computation formula to estimate causal effects of exposures. In practice, these models are often specified using parametric regression models. As such, the usual conventions regarding regression model specification apply. This paper outlines strategies for marginal structural model specification and considerations for the functional form of the exposure metric in the final structural model. We propose a quasi-likelihood information criterion adapted from use in generalized estimating equations. We evaluate the properties of our proposed information criterion using a limited simulation study. We illustrate our approach using two empirical examples. In the first example, we use data from a randomized breastfeeding promotion trial to estimate the effect of breastfeeding duration on infant weight at 1 year. In the second example, we use data from two prospective cohorts studies to estimate the effect of highly active antiretroviral therapy on CD4 count in an observational cohort of HIV-infected men and women. The marginal structural model specified should reflect the scientific question being addressed but can also assist in exploration of other plausible and closely related questions. In marginal structural models, as in any regression setting, correct inference depends on correct model specification. Our proposed information criterion provides a formal method for comparing model fit for different specifications.

Could early antiretroviral therapy entail more risks than benefits in sub-Saharan African HIV-infected adults? A model-based analysis

BACKGROUND

Initiation of antiretroviral therapy (ART) in all HIV-infected adults, regardless of CD4⁺ T-cell count, is a proposed strategy for reducing HIV transmission. We investigated the conditions under which starting ART early could entail more risks than benefits for patients with high CD4⁺ T-cell counts.

METHODS

We used a simulation model to compare ART initiation upon entry to care ('immediate ART') to initiation at CD4⁺ T-cell count ≤ 350 cells/μl ('WHO 2010 ART') in African adults with CD4⁺ T-cell counts >500 cells/μl. We varied inputs to determine the combination of parameters (population characteristics, conditions of care, treatment outcomes) that would result in higher 15-year mortality with immediate ART.

RESULTS

The 15-year mortality was 56.7% for WHO 2010 ART and 51.8% for immediate ART. In one-way sensitivity analysis, lower 15-year mortality was consistently achieved with immediate ART unless the rate of fatal ART toxicity was >1.0/100 person-years, the rate of withdrawal from care was >1.2-fold higher or the rate of ART failure due to poor adherence was >4.3-fold higher on immediate than on WHO 2010 ART. In multi-way sensitivity analysis, immediate ART led to higher mortality when moderate rates of fatal ART toxicity (0.25/100 person-years) were combined with rates of withdrawal from care >1.1-fold higher and rates of treatment failure >2.1-fold higher on immediate than on WHO 2010 ART.

CONCLUSIONS

In sub-Saharan Africa, ART initiation at entry into care would improve long-term survival of patients with high CD4⁺ T-cell counts, unless it is associated with increased withdrawal from care and decreased adherence. In early ART trials, a focus on retention and adherence will be crucial.

Treatment outcomes among HIV-1 and HIV-2 infected children initiating antiretroviral therapy in a concentrated low prevalence setting in West Africa

Background

There is little data on responses to combination antiretroviral therapy (cART) among HIV-infected children in the West African region. We describe treatment outcomes among HIV-1 and HIV-2 infected children initiating cART in a research clinic in The Gambia, West Africa.

Methods

All treatment naive HIV-infected children who initiated cART according to the WHO ART guidelines for children between October 2004 and December 2009 were included in the analysis. Kaplan-Meir estimates and sign-rank test were used to investigate the responses to treatment.

Results

65 HIV-1 and five HIV-2 infected children aged < 15 years were initiated on cART over this time period. HIV-1 infected children were treated with a combination of Zidovudine or Stavudine + Lamivudine + Nevirapine or Efavirenz while children with HIV-2 were treated with Zidovudine + Lamivudine + ritonavir-boosted Lopinavir. HIV-1 infected children were followed-up for a median (IQR) duration of 20.1 months (6.9 – 34.3), with their median (IQR) age at treatment initiation, CD4% and plasma viral load at baseline found to be 4.9 years (2.1 – 9.1), 13.0% (7.0 – 16.0) and 5.4 log₁₀ copies/ml (4.4 – 6.0) respectively. The median age at treatment initiation of the five HIV-2 infected children was 12 years (range: 4.6 – 14.0) while their median baseline CD4⁺ T cell count and HIV-2 viral load were 140 cells/mm³ (Range: 40 – 570 cells/mm³) and 4.5 log₁₀copies/mL (Range: 3.1 - 4.9 log₁₀copies/mL) respectively.

Among HIV-1 infected children <5 years of age at ART initiation, the median (IQR) increases in CD4% from baseline to 12, 24 and 36 months were 14% (8 – 19; P = 0.0004), 21% (15 – 22; P = 0.005) and 15% (15 – 25; P = 0.0422) respectively, while the median (IQR) increase in absolute CD4 T cell count from baseline to 12, 24 and 36 months for those ≥5 years at ART initiation were 470 cells/mm³ (270 – 650; P = 0.0005), 230 cells/mm³ (30 – 610; P = 0.0196) and 615 cells/mm³ (250 – 1060; P = 0.0180) respectively. The proportions of children achieving undetectable HIV-1 viral load at 6-, 12-, 24- and 36 months of treatment were 24/38 (63.2%), 20/36 (55.6%), 8/22 (36.4%) and 7/12 (58.3%) respectively. The probability of survival among HIV-1 infected children after 12 months on ART was 89.9% (95% CI 78.8 – 95.3). CD4 T cell recovery was sub-optimal in all the HIV-2 infected children and none achieved virologic suppression. Two of the HIV-2 infected children died within 6 months of starting treatment while the remaining three were lost to follow-up.

Conclusions

The beneficial effects of cART among HIV-1 infected children in our setting are sustained in the first 24 months of treatment with a significant improvement in survival experience up to 36 months; however the outcome was poor in the few HIV-2 infected children initiated on cART.

HIV RNA suppression and immune restoration: can we do better?

HAART has significantly changed the natural history of HIV infection: patients receiving antiretrovirals are usually able to control viremia, even though not all virological responders adequately recover their CD4+ count. The reasons for poor immune restoration are only partially known and they include genetic, demographic and immunologic factors. A crucial element affecting immune recovery is immune activation, related to residual viremia; indeed, a suboptimal virological control (i.e., low levels of plasma HIV RNA) has been related with higher levels of chronic inflammation and all-cause mortality. The sources of residual viremia are not yet completely known, even though the most important one is represented by latently infected cells. Several methods, including 2-LTR HIV DNA and unspliced HIV RNA measurement, have been developed to estimate residual viremia and predict the outcome of antiretroviral therapy. Considering that poor immunologic responders are exposed to a higher risk of both AIDS-related and non-AIDS-related diseases, there is a need of new therapeutic strategies, including immunomodulators and drugs targeting the latent viral reservoirs, in order to face residual viremia but also to “drive” the host immunologic responses.

Assessment of the impact of adherence and other predictors during HAART on various CD4 cell responses in resource-limited settings

OBJECTIVE

The aim of this study was to quantify, by modeling, the impact of significant predictors on CD4 cell response during antiretroviral therapy in a resource-limited setting.

METHODS

Modeling was used to determine which antiretroviral therapy response predictors (baseline CD4 cell count, clinical state, age, and adherence) significantly influence immunological response in terms of CD4 cell gain compared to a reference value at different periods of monitoring.

RESULTS

At 6 months, CD4 cell response was significantly influenced by baseline CD4 count alone. The probability of no increase in CD4 cells was 2.6 higher in patients with a baseline CD4 cell count of ≥200/mm(3). At 12 months, CD4 cell response was significantly influenced by both baseline CD4 cell count and adherence. The probability of no increase in CD4 cells was three times higher in patients with a baseline CD4 cell count of ≥200/mm(3) and 0.15 times lower with adherent patients. At 18 months, CD4 cell response was also significantly influenced by both baseline CD4 cell count and adherence. The probability of no increase in CD4 cells was 5.1 times higher in patients with a baseline CD4 cell count of ≥200/mm(3) and 0.28 times lower with adherent patients. At 24 months, optimal CD4 cell response was significantly influenced by adherence alone. Adherence increased the probability (by 5.8) of an optimal increase in CD4 cells. Age and baseline clinical state had no significant influence on immunological response.

CONCLUSION

The relationship between adherence and CD4 cell response was the most significant compared to that of baseline CD4 cell count. Counseling before initiation of treatment and educational therapy during follow-up must always help to strengthen adherence and optimize the efficiency of antiretroviral therapy in a resource-limited setting.

CD4+ T-cell counts and plasma HIV-1 RNA levels beyond 5 years of highly active antiretroviral therapy

BACKGROUND

The heterogeneity of CD4 T-cell counts and HIV-1 RNA at 5-12 years after the initiation of highly active antiretroviral therapy (HAART) remains largely uncharacterized.

METHODS

In the Multicenter AIDS Cohort Study, 614 men who initiated HAART contributed data 5-12 years subsequently. Multivariate regression was used to evaluate the predictors of CD4 counts and HIV-1 RNA levels.

RESULTS

At 5 to 12 years post-HAART, the median CD4 T-cell count was 586 (interquartile range, 421-791) cells per microliter and 78% of the HIV-1 RNA measurements were undetectable. Higher CD4 T-cell counts 5-12 years post HAART were predicted by higher CD4 T-cell counts and higher total lymphocyte count pre HAART, lack of hepatitis B or C virus coinfections, and greater CD4 T-cell change and suppressed HIV-1 RNA in the first 5 years after starting HAART. Men who were 50 years and older with 351-500 CD4 cells per microliter at HAART initiation had adjusted mean CD4 T-cell count of 643 cells per microliter at 10-12 years post HAART, which was similar to the adjusted mean CD4 T-cell count (670 cells/μL, P = 0.45) in this period for younger men starting HAART with lower CD4 T-cell counts. HIV-1 RNA suppression in the first 5 years post HAART predicted subsequent viral suppression.

CONCLUSIONS

Immunological and virological responses in the first 5 years post HAART predicted subsequent CD4 T-cell counts and HIV-1 RNA levels. The association between age and subsequent CD4 T-cell count supports incorporating age in the guidelines for use of HAART.

Factors influencing the normalization of CD4+ T-cell count, percentage and CD4+/CD8+ T-cell ratio in HIV-infected patients on long-term suppressive antiretroviral therapy

We evaluated factors associated with normalization of the absolute CD4+ T-cell counts, per cent CD4+ T cells and CD4+/CD8+ T-cell ratio. A multicentre observational study was carried out in patients with sustained HIV-RNA <50 copies/mL. Outcomes were: CD4-count >500/mm(3) and multiple T-cell marker recovery (MTMR), defined as CD4+ T cells >500/mm(3) plus%CD4 T cells >29%plus CD4+/CD8+ T-cell ratio >1. Kaplan-Meier survival analysis and Cox regression analyses to predict odds for achieving outcomes were performed. Three hundred and fifty-two patients were included and followed-up for a median of 4.1 (IQR 2.1-5.9) years, 270 (76.7%) achieving a CD4+ T-cell count >500 cells/mm(3) and 197 (56%) achieving MTMR. Using three separate Cox models for both outcomes we demonstrated that independent predictors were: both absolute CD4+ and CD8+ T-cell counts, %CD4+ T cells, a higher CD4+/CD8+ T-cell ratio, and age. A likelihood-ratio test showed significant improvements in fitness for the prediction of either CD4+ >500/mm(3) or MTMR by multivariable analysis when the other immune markers at baseline, besides the absolute CD4+ count alone, were considered. In addition to baseline absolute CD4+ T-cell counts, pretreatment %CD4+ T cells and the CD4+/CD8+ T-cell ratio influence recovery of T-cell markers, and their consideration should influence the decision to start antiretroviral therapy. However, owing to the small sample size, further studies are needed to confirm these results in relation to clinical endpoints.

[Modeling of antiretroviral response from taxonomy of CD4 cells count trajectories in profound immunodeficiency setting]

Modeling of CD4 cells counts response was performed through a Non-Hierarchical-descendant process with profoundly immunocompromised symptomatic patients under nevirapine or efavirenz-based antiretroviral regimen in Abidjan. Similar CD4 cells count trajectories have been modelled in meta-trajectories linked to patients' classes. Global immunological response is similar between "nevirapine group" and "efavirenz group" but the model showed an internal variation of this response in each group. In the both groups, some variables presented a significant variation between classes: average CD4, CD4 Nadir, CD4 peak and average gain of CD4. In "nevirapine group", these following parameters vary significantly between classes: mean weight, mean haemoglobin count and mean increase in haemoglobin count and sex. It's also important to note that, all meta-trajectories began with distinctive categories of baseline CD4 cells counts. Other explanatory factors must be sought because the characteristics we have chosen to describe patients'classes, are not exhaustive.

Clinical predictors of immune reconstitution following combination antiretroviral therapy in patients from the Australian HIV Observational Database

Background

A small but significant number of patients do not achieve CD4 T-cell counts >500cells/µl despite years of suppressive cART. These patients remain at risk of AIDS and non-AIDS defining illnesses. The aim of this study was to identify clinical factors associated with CD4 T-cell recovery following long-term cART.

Methods

Patients with the following inclusion criteria were selected from the Australian HIV Observational Database (AHOD): cART as their first regimen initiated at CD4 T-cell count <500cells/µl, HIV RNA<500copies/ml after 6 months of cART and sustained for at least 12 months. The Cox proportional hazards model was used to identify determinants associated with time to achieve CD4 T-cell counts >500cells/µl and >200cells/µl.

Results

501 patients were eligible for inclusion from AHOD (n = 2853). The median (IQR) age and baseline CD4 T-cell counts were 39 (32–47) years and 236 (130–350) cells/µl, respectively. A major strength of this study is the long follow-up duration, median (IQR) = 6.5(3–10) years. Most patients (80%) achieved CD4 T-cell counts >500cells/µl, but in 8%, this took >5 years. Among the patients who failed to reach a CD4 T-cell count >500cells/µl, 16% received cART for >10 years. In a multivariate analysis, faster time to achieve a CD4 T-cell count >500cells/µl was associated with higher baseline CD4 T-cell counts (p<0.001), younger age (p = 0.019) and treatment initiation with a protease inhibitor (PI)-based regimen (vs. non-nucleoside reverse transcriptase inhibitor, NNRTI; p = 0.043). Factors associated with achieving CD4 T-cell counts >200cells/µl included higher baseline CD4 T-cell count (p<0.001), not having a prior AIDS-defining illness (p = 0.018) and higher baseline HIV RNA (p<0.001).

Conclusion

The time taken to achieve a CD4 T-cell count >500cells/µl despite long-term cART is prolonged in a subset of patients in AHOD. Starting cART early with a PI-based regimen (vs. NNRTI-based regimen) is associated with more rapid recovery of a CD4 T-cell count >500cells/µl.

Clinical audit: virological and immunological response to combination antiretroviral therapy in HIV patients at a Sydney sexual health clinic

AIM

Bigge Park Centre (BPC) is a sexual health clinic located in a socially disadvantaged area in Southwest Sydney. This served as a retrospective clinical audit, documenting patient demographics, identifying factors associated with virological, immunological and discordant responses, evaluating the centre's ability in HIV control and investigating changes in practice from 1996 to 2007.

METHOD

Data including age, gender, ethnicity, mode of transmission, hepatitis co-infection, prior acquired immune deficiency syndrome (AIDS)-defining-illness, HIV-1 RNA and CD4+cell counts of patients on combination antiretroviral therapy (CART) for treatment of HIV with at least 1-year follow up at the BPC were analysed. Results were compared with other cohorts in medical literature.

RESULTS

BPC manages HIV patients from diverse backgrounds. Sequential monotherapy was associated with poor virological control, lower CD4+cell recovery and discordant response. When patients who had sequential monotherapy were excluded, Caucasian race, high viral load at 1 month and triple-NRTI (nucleoside reverse transcriptase inhibitor) regimen were associated with lack of virological control. Lower baseline viral load and triple-NRTI regimen were associated with lower CD4+cell recovery. Lower baseline CD4+cell count and prior diagnosis of AIDS were associated with discordant response. Virological control and CD4+cell recovery achieved were comparable to that documented in medical literature. There was no significant change over time in terms of timing of CART initiation, attainment of immunological response or virological control since the late 1990 s.

CONCLUSION

HIV control achieved at the BPC was comparable to that reported in medical literature. Enhancement of strategies to promote screening and improve adherence as well as performance of HIV resistance assessment and avoidance of triple-NRTI therapy will likely improve patient care.

[Study of meta-trajectories of CD4 cells count from taxonomy in the antiretroviral response of efavirenz-based regimen with naive symptomatic patients in Abidjan]

INTRODUCTION

Sub-Saharan Africa remains the most affected region in the global AIDS epidemic. Côte d'Ivoire is one of the most affected countries by this epidemic. The collective search for deleterious determinants of the evolution of immunological markers (CD4 cells count) may help to optimize the therapeutic efficiency in this resource-limited country.

PATIENTS AND METHODS

We are interested in studying the antiretroviral response of efavirenz-based regimen (treatment of choice in first line) by the nonhierarchical-descendant model by taxonomy of CD4 cells count trajectories. From 87 CD4 cells count trajectories of symptomatic naive patients, classes of similar profiles grouped by the model have formed typical profiles of evolution as meta-trajectories. The analysis of these meta-trajectories was used to study the determinants of CD4 cells count evolution by classes of patients.

RESULTS

Four classes have been determined for an optimal taxonomy with a partition score of 0.72: P1 (n=27), P2 (n=15), P3 (n=24), P4 (n=21). Our model showed a variation between groups of CD4 cells count trajectories linked to explanatory factors by highlighting the predictive role of certain characteristics on antiretroviral response in Côte d'Ivoire (CD4 cells count baseline [P<0.01], CD4 percentage baseline [P<0.05], adherence [P<0.05]). The multiple correspondence analysis revealed other characteristics that influence the immune response such as the presence of opportunistic infections, bloodless status and weight at the initiation of treatment.

CONCLUSION

The factors influencing the profile of meta-trajectories of CD4 cells count during efavirenz-based antiretroviral regimen should be considered at the initiation of treatment to optimize performance in the therapeutic monitoring of patients in Abidjan. The model of biomedical indicators meta-trajectories provides a therapeutic decision support provided prior to capitalize sufficient expertise for a better interpretation.

Immunodeficiency and the risk of serious clinical endpoints in a well studied cohort of treated HIV-infected patients

OBJECTIVE

To investigate the relative predictive value of CD4(+) metrics for serious clinical endpoints.

DESIGN

Observational.

METHODS

Patients (3012; 20 317 person-years) from control arms of ESPRIT and SILCAAT were followed prospectively. We used Cox regression to identify CD4(+) metrics (latest, baseline and nadir CD4(+) cell count, latest CD4(+)%, time spent with CD4(+) count below certain thresholds and CD4(+) slopes) independently predictive of all-cause mortality, non-AIDS deaths, non-AIDS (cardiovascular, hepatic, renal and non-AIDS malignancy) and AIDS events. Akaike information criteria (AIC) were calculated for each model. Significant metrics (P < 0.05) were then additionally adjusted for latest CD4(+) cell count.

RESULTS

Non-AIDS deaths occurred at a higher rate than AIDS deaths [rate ratio: 6.48, 95% confidence interval (CI) 5.1-8.1], and non-AIDS events likewise (rate ratio: 1.72, 95% CI 1.65-1.79). Latest CD4(+) cell count was strongly predictive of lower risk of death (hazard ratio per log2 rise: 0.48, 95% CI 0.43-0.54), with lowest AIC of all metrics. CD4(+) slope over seven visits, after additional adjustment for latest CD4(+) cell count, was the only metric to be an independent predictor for all-cause (hazard ratio for slope <-10 cells/microl per month vs. 0 +/- 10: 3.04, 95% CI 1.98-4.67) and non-AIDS deaths (hazard ratio for slope <-10 cells/microl per month vs. 0 +/- 10: 2.62, 95% CI 1.62-4.22). Latest CD4(+) cell count (per log(2) rise) was the best predictor across all four endpoints and predicted hepatic (hazard ratio 0.46, 95% CI 0.33-0.63) and renal events (hazard ratio 0.39, 95% CI 0.21-0.70), but not cardiovascular events (hazard ratio 1.05, 95% CI 0.77-1.43) or non-AIDS cancers (hazard ratio 0.78, 95% CI 0.59-1.03).

CONCLUSION

Latest CD4(+) cell count is the best predictor of serious endpoints. CD4(+) slope independently predicts all-cause and non-AIDS deaths.

The effect of HAART on HIV RNA trajectory among treatment-naïve men and women: a segmental Bernoulli/lognormal random effects model with left censoring

BACKGROUND

Highly active antiretroviral therapy (HAART) rapidly suppresses human immunodeficiency virus (HIV) viral replication and reduces circulating viral load, but the long-term effects of HAART on viral load remain unclear.

METHODS

We evaluated HIV viral load trajectories over 8 years following HAART initiation in the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study. The study included 157 HIV-infected men and 199 HIV-infected women who were antiretroviral naive and contributed 1311 and 1837 semiannual person-visits post-HAART, respectively. To account for within-subject correlation and the high proportion of left-censored viral loads, we used a segmental Bernoulli/lognormal random effects model.

RESULTS

Approximately 3 months (0.30 years for men and 0.22 years for women) after HAART initiation, HIV viral loads were optimally suppressed (ie, with very low HIV RNA) for 44% (95% confidence interval = 39%-49%) of men and 43% (38%-47%) of women, whereas the other 56% of men and 57% of women had on average 2.1 (1.5-2.6) and 3.0 (2.7-3.2) log10 copies/mL, respectively.

CONCLUSION

After 8 years on HAART, 75% of men and 80% of women had optimal suppression, whereas the rest of the men and women had suboptimal suppression with a median HIV RNA of 3.1 and 3.7 log10 copies/mL, respectively.

Long-term patterns in CD4 response are determined by an interaction between baseline CD4 cell count, viral load, and time: The Asia Pacific HIV Observational Database (APHOD)

BACKGROUND

Random effects models were used to explore how the shape of CD4 cell count responses after commencing combination antiretroviral therapy (cART) develop over time and, in particular, the role of baseline and follow-up covariates.

METHODS

Patients in Asia Pacific HIV Observational Database who first commenced cART after January 1, 1997, and who had a baseline CD4 cell count and viral load measure and at least 1 follow-up measure between 6 and 24 months, were included. CD4 cell counts were determined at every 6-month period after the commencement of cART for up to 6 years.

RESULTS

A total of 1638 patients fulfilled the inclusion criteria with a median follow-up time of 58 months. Lower post-cART mean CD4 cell counts were found to be associated with increasing age (P < 0.001), pre-cART hepatitis C coinfection (P = 0.038), prior AIDS (P = 0.019), baseline viral load < or equal to 100,000 copies per milliliter (P < 0.001), and the Asia Pacific region compared with Australia (P = 0.005). A highly significant 3-way interaction between the effects of time, baseline CD4 cell count, and post-cART viral burden (P < 0.0001) was demonstrated. Higher long-term mean CD4 cell counts were associated with lower baseline CD4 cell count and consistently undetectable viral loads. Among patients with consistently detectable viral load, CD4 cell counts seemed to converge for all baseline CD4 levels.

CONCLUSIONS

Our analysis suggest that the long-term shape of post-cART CD4 cell count changes depends only on a 3-way interaction between baseline CD4 cell count, viral load response, and time.

Relationship between a frailty-related phenotype and progressive deterioration of the immune system in HIV-infected men

CONTEXT

Immunological similarities have been noted between HIV-infected individuals and older HIV-negative adults. Immunologic alterations with aging have been noted in frailty in older adults, a clinical syndrome of high risk for mortality and other adverse outcomes. Using a frailty-related phenotype (FRP), we investigated in the Multicenter AIDS Cohort Study whether progressive deterioration of the immune system among HIV-positive individuals independently predicts onset of FRP.

METHODS

FRP was evaluated semiannually in 1046 HIV-infected men from 1994 to 2005. CD4 T-cell count and plasma viral load were evaluated as predictors of FRP by logistic regression (generalized estimating equations), adjusting for age, ethnicity, educational level, AIDS status, and treatment era [pre-highly active antiretroviral therapy (HAART) (1994-1995) and HAART (1996-1999 and 2000-2005)].

RESULTS

Adjusted prevalences of FRP remained low for CD4 T-cell counts >400 cells per cubic millimeter and increased exponentially and significantly for lower counts. Results were unaffected by treatment era. After 1996, CD4 T-cell count, but not plasma viral load, was independently associated with FRP.

CONCLUSIONS

CD4 T-cell count predicted the development of a FRP among HIV-infected men, independent of HAART use. This suggests that compromise of the immune system in HIV-infected individuals contributes to the systemic physiologic dysfunction of frailty.

Incomplete peripheral CD4+ cell count restoration in HIV-infected patients receiving long-term antiretroviral treatment

BACKGROUND

Although antiretroviral therapy has the ability to fully restore a normal CD4(+) cell count (>500 cells/mm(3)) in most patients, it is not yet clear whether all patients can achieve normalization of their CD4(+) cell count, in part because no study has followed up patients for >7 years.

METHODS

Three hundred sixty-six patients from 5 clinical cohorts who maintained a plasma human immunodeficiency virus (HIV) RNA level 1000 copies/mL for at least 4 years after initiation of antiretroviral therapy were included. Changes in CD4(+) cell count were evaluated using mixed-effects modeling, spline-smoothing regression, and Kaplan-Meier techniques.

RESULTS

The majority (83%) of the patients were men. The median CD4(+) cell count at the time of therapy initiation was 201 cells/mm(3) (interquartile range, 72-344 cells/mm(3)), and the median age was 47 years. The median follow-up period was 7.5 years (interquartile range, 5.5-9.7 years). CD4(+) cell counts continued to increase throughout the follow-up period, albeit slowly after year 4. Although almost all patients (95%) who started therapy with a CD4(+) cell count 300 cells/mm(3) were able to attain a CD4(+) cell count 500 cells/mm(3), 44% of patients who started therapy with a CD4(+) cell count <100 cells/mm(3) and 25% of patients who started therapy with a CD4(+) cell count of 100-200 cells/mm(3) were unable to achieve a CD4(+) cell count >500 cells/mm(3) over a mean duration of follow-up of 7.5 years; many did not reach this threshold by year 10. Twenty-four percent of individuals with a CD4(+) cell count <500 cells/mm(3) at year 4 had evidence of a CD4(+) cell count plateau after year 4. The frequency of detectable viremia ("blips") after year 4 was not associated with the magnitude of the CD4(+) cell count change.

CONCLUSIONS

A substantial proportion of patients who delay therapy until their CD4(+) cell count decreases to <200 cells/mm(3) do not achieve a normal CD4(+) cell count, even after a decade of otherwise effective antiretroviral therapy. Although the majority of patients have evidence of slow increases in their CD4(+) cell count over time, many do not. These individuals may have an elevated risk of non-AIDS-related morbidity and mortality.

CCL3L1-CCR5 genotype improves the assessment of AIDS Risk in HIV-1-infected individuals

BACKGROUND

Whether vexing clinical decision-making dilemmas can be partly addressed by recent advances in genomics is unclear. For example, when to initiate highly active antiretroviral therapy (HAART) during HIV-1 infection remains a clinical dilemma. This decision relies heavily on assessing AIDS risk based on the CD4+ T cell count and plasma viral load. However, the trajectories of these two laboratory markers are influenced, in part, by polymorphisms in CCR5, the major HIV coreceptor, and the gene copy number of CCL3L1, a potent CCR5 ligand and HIV-suppressive chemokine. Therefore, we determined whether accounting for both genetic and laboratory markers provided an improved means of assessing AIDS risk.

METHODS AND FINDINGS

In a prospective, single-site, ethnically-mixed cohort of 1,132 HIV-positive subjects, we determined the AIDS risk conveyed by the laboratory and genetic markers separately and in combination. Subjects were assigned to a low, moderate or high genetic risk group (GRG) based on variations in CCL3L1 and CCR5. The predictive value of the CCL3L1-CCR5 GRGs, as estimated by likelihood ratios, was equivalent to that of the laboratory markers. GRG status also predicted AIDS development when the laboratory markers conveyed a contrary risk. Additionally, in two separate and large groups of HIV+ subjects from a natural history cohort, the results from additive risk-scoring systems and classification and regression tree (CART) analysis revealed that the laboratory and CCL3L1-CCR5 genetic markers together provided more prognostic information than either marker alone. Furthermore, GRGs independently predicted the time interval from seroconversion to CD4+ cell count thresholds used to guide HAART initiation.

CONCLUSIONS

The combination of the laboratory and genetic markers captures a broader spectrum of AIDS risk than either marker alone. By tracking a unique aspect of AIDS risk distinct from that captured by the laboratory parameters, CCL3L1-CCR5 genotypes may have utility in HIV clinical management. These findings illustrate how genomic information might be applied to achieve practical benefits of personalized medicine.

CCL3L1-CCR5 genotype influences durability of immune recovery during antiretroviral therapy of HIV-1-infected individuals

The basis for the extensive variability seen in the reconstitution of CD4(+) T cell counts in HIV-infected individuals receiving highly active antiretroviral therapy (HAART) is not fully known. Here, we show that variations in CCL3L1 gene dose and CCR5 genotype, but not major histocompatibility complex HLA alleles, influence immune reconstitution, especially when HAART is initiated at <350 CD4(+) T cells/mm(3). The CCL3L1-CCR5 genotypes favoring CD4(+) T cell recovery are similar to those that blunted CD4(+) T cell depletion during the time before HAART became available (pre-HAART era), suggesting that a common CCL3L1-CCR5 genetic pathway regulates the balance between pathogenic and reparative processes from early in the disease course. Hence, CCL3L1-CCR5 variations influence HIV pathogenesis even in the presence of HAART and, therefore, may prospectively identify subjects in whom earlier initiation of therapy is more likely to mitigate immunologic failure despite viral suppression by HAART. Furthermore, as reconstitution of CD4(+) cells during HAART is more sensitive to CCL3L1 dose than to CCR5 genotypes, CCL3L1 analogs might be efficacious in supporting immunological reconstitution.

Importance of baseline prognostic factors with increasing time since initiation of highly active antiretroviral therapy: collaborative analysis of cohorts of HIV-1-infected patients

BACKGROUND

The extent to which the prognosis for AIDS and death of patients initiating highly active antiretroviral therapy (HAART) continues to be affected by their characteristics at the time of initiation (baseline) is unclear.

METHODS

We analyzed data on 20,379 treatment-naive HIV-1-infected adults who started HAART in 1 of 12 cohort studies in Europe and North America (61,798 person-years of follow-up, 1844 AIDS events, and 1005 deaths).

RESULTS

Although baseline CD4 cell count became less prognostic with time, individuals with a baseline CD4 count <25 cells/microL had persistently higher progression rates than individuals with a baseline CD4 count >350 cells/microL (hazard ratio for AIDS = 2.3, 95% confidence interval [CI]: 1.0 to 2.3; mortality hazard ratio = 2.5, 95% CI: 1.2 to 5.5, 4 to 6 years after starting HAART). Rates of AIDS were persistently higher in individuals who had experienced an AIDS event before starting HAART. Individuals with presumed transmission by means of injection drug use experienced substantially higher rates of AIDS and death than other individuals throughout follow-up (AIDS hazard ratio = 1.6, 95% CI: 0.8 to 3.0; mortality hazard ratio = 3.5, 95% CI: 2.2 to 5.5, 4 to 6 years after starting HAART).

CONCLUSIONS

Compared with other patient groups, injection drug users and patients with advanced immunodeficiency at baseline experience substantially increased rates of AIDS and death up to 6 years after starting HAART.

Long-term evolution of CD4 count in patients with a plasma HIV RNA persistently <500 copies/mL during treatment with antiretroviral drugs

BACKGROUND

The increase in CD4 count may reach a plateau after some duration of virological response to highly active antiretroviral therapy (HAART).

METHODS

A total of 1281 HIV-infected patients initiating HAART were enrolled in the AntiPROtease (APROCO) cohort. We investigated determinants of increase in CD4 count using longitudinal mixed models in patients who maintained a plasma HIV RNA <500 HIV-1 RNA copies/mL.

RESULTS

A total of 870 patients had a virological response at month 4. The median follow-up time was 57 months. Mean estimated increases in CD4 count in patients with persistent virological response were 29.9 cells/muL/month before month 4, 6.4 cells/microL/month between months 4 and 36, and 0.7 cells/microL/month (not significantly different from 0) after month 36. Three factors were associated with a significantly positive CD4 count slope after month 36: male gender (+0.9), no history of antiretroviral therapy at baseline (+1.7) and baseline CD4 count <100 cells/microL (+2.6). In patients who maintained a virological response after 5 years of HAART, a CD4 count >500 cells/microL was achieved in 83% of those with a baseline CD4 count >or=200 cells/microL and in 45% of those with a baseline CD4 count <200 cells/microL.

CONCLUSION

The increase in CD4 count reaches a plateau after 3 years of virological response. Even if patients initiating HAART with low CD4 counts still show a CD4 count increase after 3 years, it remains insufficient to overcome immune deficiency in all patients.

Normalisation of CD4 counts in patients with HIV-1 infection and maximum virological suppression who are taking combination antiretroviral therapy: an observational cohort study

BACKGROUND

Combination antiretroviral therapy (cART) has been shown to reduce mortality and morbidity in patients with HIV. As viral replication falls, the CD4 count increases, but whether the CD4 count returns to the level seen in HIV-negative people is unknown. We aimed to assess whether the CD4 count for patients with maximum virological suppression (viral load <50 copies per mL) continues to increase with long-term cART to reach levels seen in HIV-negative populations.

METHODS

We compared increases in CD4 counts in 1835 antiretroviral-naive patients who started cART from EuroSIDA, a pan-European observational cohort study. Rate of increase in CD4 count (per year) occurring between pairs of consecutive viral loads below 50 copies per mL was estimated using generalised linear models, accounting for multiple measurements for individual patients.

FINDINGS

The median CD4 count at starting cART was 204 cells per microL (IQR 85-330). The greatest mean yearly increase in CD4 count of 100 cells per microL was seen in the year after starting cART. Significant, but lower, yearly increases in CD4 count, around 50 cells per microL, were seen even at 5 years after starting cART in patients whose current CD4 count was less than 500 cells per microL. The only groups without significant increases in CD4 count were those where cART had been taken for more than 5 years with a current CD4 count of more than 500 cells per microL, (current mean CD4 count 774 cells per microL; 95% CI 764-783). Patients starting cART with low CD4 counts (<200 cells per microL) had significant rises in CD4 counts even after 5 years of cART.

INTERPRETATION

Normalisation of CD4 counts in HIV-infected patients for all infected individuals might be achievable if viral suppression with cART can be maintained for a sufficiently long period of time.

Baseline Viral Load and Immune Activation Determine the Extent of Reconstitution of Innate Immune Effectors in HIV-1-Infected Subjects Undergoing Antiretroviral Treatment

We analyzed dendritic cell (DC) and NK cell compartments in relation to CD4 recovery in 21 HIV-infected subjects followed to <50 copies/ml once starting antiretroviral therapy (ART) and observed for 52 wk of sustained suppression. Although CD4 counts increased in all subjects in response to ART, we observed a restoration of functional plasmacytoid DC (PDC) after 52 wk of sustained suppression under ART (from 1850 cells/ml to 4550 cells/ml) to levels comparable to controls (5120 cells/ml) only in subjects with a low baseline viral load, which also rapidly suppressed to <50 copies/ml upon <or=60 days from ART initiation. Recovery of PDC at week 52 correlates with level of CD95 expression on CD8 T cells and PDC frequency following first ART suppression. NK cytotoxic activity increased rapidly upon viral suppression (VS) and correlated with PDC function at week 52. However, restoration of total NK cells was incomplete even after 52 wk on ART (73 cells/mul vs 122 cells/mul in controls). Direct reconstitution experiments indicate that NK cytotoxic activity against virally infected target cells requires DC/NK cooperation, and can be recovered upon sustained VS and recovery of functional PDC (but not myeloid DC) from ART-suppressed subjects. Our data indicate that viremic HIV-infected subjects may have different levels of reconstitution of DC and NK-mediated function following ART, with subjects with lower initial viremia and the greatest reduction of baseline immune activation at VS achieving the greatest level of innate effector cell reconstitution.

Bimodal virological response to antiretroviral therapy for HIV infection: an application using a mixture model with left censoring

STUDY OBJECTIVE

To assess whether HIV RNA levels (log(10) scale) in highly active antiretroviral therapy (HAART) treated population have a bimodal distribution, suggesting optimal or suboptimal response to HAART.

METHODS

The study population from two ongoing cohort studies comprised 564 men (4785 person visits) and 1173 women (8675 person visits) with known dates of HAART initiation and with HIV RNA measurements before and after initiation. Values below detection limit of assays were treated in the analysis as left censored. Maximum likelihood methods were used to estimate parameters and to determine possible bimodality of HIV RNA distributions.

RESULTS

A two component mixture model fitted HIV RNA levels significantly better than did a single component distribution at different years from HAART initiation in both therapy experienced and therapy naive patients. In the fifth year after HAART initiation, 32% of men and 44% of women had HIV RNA in the higher component with medians of 5247 and 9253 copies/ml, respectively, suggesting suboptimal virological response to HAART, which was associated with poor adherence and lower frequency of CCR5 heterozygous genotype.

CONCLUSION

The bimodal distribution of HIV RNA persisted during the years after HAART initiation. The high occurrence of suboptimal virological response at the fifth year after HAART initiation underscore the needs for careful monitoring and patient education about the importance of treatment adherence. This data analysis overcomes limitations of measurement techniques of observations having values below detection limits and serves to characterise the dynamics of the virological response to therapies.

CD4+ Cell Count 6 Years after Commencement of Highly Active Antiretroviral Therapy in Persons with Sustained Virologic Suppression

BACKGROUND

Sustained suppression of the human immunodeficiency virus (HIV) type 1 RNA load with the use of highly active antiretroviral therapy (HAART) results in immunologic improvement, but it is not clear whether the CD4(+) cell count increases to normal levels or whether it reaches a less-than-normal plateau. We characterized the increase in the CD4(+) cell count in patients in clinical practice who maintained sustained viral suppression for up to 6 years.

METHODS

All patients were from the Johns Hopkins HIV Clinical Cohort, a longitudinal observational study of patients receiving primary HIV care in Baltimore, Maryland, who were observed for >1 year while receiving HAART and who had sustained suppression of the HIV RNA load at <400 copies/mL. We analyzed annual change in the CD4(+) cell count for up to 6 years after the start of HAART, stratified by baseline CD4(+) cell counts of < or =200, 201-350, >350 cells/microL, and we assessed the development of clinical events (death and new acquired immunodeficiency syndrome-defining illness) by Kaplan-Meier analysis.

RESULTS

A total of 655 patients were observed for a median of 46 months (range, 13-72 months). The median change from baseline to most recent CD4(+) cell count was +274 cells/microL, with 92% of patients having an increase in CD4(+) cell count. By 6 years, the median CD4(+) cell count was 493 cells/microL among patients with baseline CD4(+) cell counts < or =200 cells/microL, 508 cells/microL among those with baseline CD4(+) cell counts of 201-350 cells/microL, and 829 cells/microL among those with baseline CD4(+) cell counts >350 cells/microL. In addition to baseline CD4(+) cell count, injection drug use and older age were associated with a lesser CD4(+) cell count response, and duration of therapy was associated with a greater CD4(+) cell count response.

CONCLUSION

Only patients with baseline CD4(+) cell counts >350 cells/microL returned to nearly normal CD4(+) cell counts after 6 years of follow-up. Significant increases were observed in all CD4(+) cell count strata during the first year, but there was a lower plateau CD4(+) cell count at lower baseline CD4(+) cell strata. These data suggest that waiting to start HAART at lower CD4(+) cell counts will result in the CD4(+) cell count not returning to normal levels.

Evidence of ongoing immune reconstitution in subjects with sustained viral suppression following 6 years of lopinavir-ritonavir treatment

BACKGROUND

We evaluated the immunologic impact of highly active antiretroviral therapy in subjects who maintained human immunodeficiency virus type 1 (HIV-1) suppression through 6 years of receiving a lopinavir-ritonavir-based regimen.

METHODS

A total of 100 antiretroviral-naive subjects with any CD4+ T cell count initiated therapy with lopinavir-ritonavir, stavudine, and lamivudine. Sixty-three subjects who remained in the study for 6 years were assessed. Laboratory measurements included plasma HIV-1 RNA levels, multiparameter flow cytometry of immune cells, and markers of maturation and activation.

RESULTS

After 6 years, 62 of 63 subjects had plasma HIV-1 RNA levels <50 copies/mL. The mean increase in CD4+ T cell count was 528 cells/microL (P<.001), and 81% of subjects had CD4+ T cell counts >500 cells/microL, compared with 21% of subjects at baseline. The mean ratio of CD4+ T cell count to CD8+ T cell count increased from 0.38 at baseline to 0.96 at year 6 (P<.001). The percentage of subjects with cell counts below the lower limit of normal at year 6, compared with at baseline, was significantly decreased for total T cells, B cells, and natural killer cells. At year 6, the median CD4+ T cell activation level was 3.4%, and the median CD8+ T cell activation level was 5.8%.

CONCLUSIONS

The receipt of a lopinavir-ritonavir-based regimen resulted in ongoing immune reconstitution through 6 years of therapy in a cohort of HIV-1-infected, antiretroviral-naive subjects with suppressed HIV-1 RNA levels. Normalization of activation marker expression on CD4+ and CD8+ T cell subsets was demonstrated.

Long-Term Effects of Highly Active Antiretroviral Therapy in Pretreated, Vertically HIV Type 1-Infected Children: 6 Years of Follow-Up

BACKGROUND

Several studies of children with human immunodeficiency virus (HIV) type 1 infection have demonstrated sustained increases in CD4+ cell count, even when virological failure has occurred after receipt of highly active antiretroviral therapy (HAART), but these studies were of limited duration. Moreover, the CD4+ cell count threshold at which antiretroviral treatment should be initiated is still unsettled. The aim of this study was to define the long-term impact of HAART on CD4+ cell percentage and viral load according to CD4+ cell percentages before HAART was initiated.

METHODS

We conducted a retrospective study of 113 pretreated HIV-1-infected children stratified by pre-HAART CD4+ cell percentage (<5%, 5%-15%, 15%-25%, and >25%). The inclusion criteria were as follows: initiating HAART with a protease inhibitor, having 6 years of follow-up after starting HAART, having a CD4+ cell count or viral load recorded before initiation of HAART, and having received mono- or dual-nucleoside therapy before starting HAART.

RESULTS

During the first 2 years of HAART, HIV-1-infected children experienced a significant increase in CD4+ cell percentage and a decrease in viral load (P<.05). During their last 4 years of receiving HAART, we found a significant decrease in viral load but not an increase in CD4+ cell percentage, because the CD4+ cell percentage reached a plateau after the second year of HAART. Moreover, children with CD4+ cell percentages of <5% at baseline did not achieve CD4+ cell percentages of >25% after 6 years of HAART. Children with CD4+ cell percentages of 5%-25% at baseline had a strong negative association with achieving CD4+ cell percentages of >30% for at least 6 and 12 months but not with achieving CD4+ cell percentages of >30% for at least 24 months.

CONCLUSIONS

Long-term HAART allowed for restoration of CD4+ cell counts and control of viral loads in HIV-1-infected children. However, initiating HAART after severe immunosuppression has occurred is detrimental for the restoration of the CD4+ cell count.

Impact of long-term viral suppression in CD4+ recovery of HIV-children on Highly Active Antiretroviral Therapy

BACKGROUND

The effects of HAART may differ between children and adults because children have a developing immune system, and the long-term immunological outcome in HIV-infected children on HAART is not well-known. A major aim of our study was to determine CD4+ evolution associated with long-term VL control during 4 years of observation on HAART.

METHODS

We carried out a retrospective study on a cohort of 160 vertically HIV-infected children. It was carried out from 1996 to 2004 in six large Spanish pediatric referral hospitals. We compared 33 children who had long-term VL suppression (VL < or = 400 copies/ml) in the first 12 months of follow-up and maintained that level throughout follow-up (Responders-group), and 127 children with persistently detectable VL in spite of ART switches (Non-Responders-group).

RESULTS

We observed a quick initial and significant increase in CD4+ counts from the baseline to 12 months on HAART in both groups (p < 0.01). The Non-Responders group sustained CD4+ increases and most of these children maintained high CD4+ level counts (> or = 25%). The Non-Responders group reached a plateau between 26% and 27% CD4+ at the first 12 months of follow-up that remained stable during the following 3 years. However, the Responders group reached a plateau between 30% and 32% CD4+ at 24, 36 and 48 months of follow-up. We found that the Responders group had higher CD4+ count values and higher percentages of children with CD4+ > or = 25% than the Non-Responders group (p < 0.05) after month 12.

CONCLUSION

Long-term VL suppression in turn induces large beneficial effects in immunological responses. However, it is not indispensable to recover CD4+ levels.

Virologic and immunologic response to highly active antiretroviral therapy

Highly active antiretroviral therapy (HAART) delays clinical progression by suppressing viral replication, measured by a substantial reduction in HIV RNA, allowing the immune system to reconstitute, measured in most studies by an increase in CD4 cells. These virologic and immunologic consequences do not occur uniformly among HAART users. Markers of HIV disease stage at the time of HAART initiation are critical determinants of the progression while receiving HAART. In this report, we review studies describing the heterogeneous virologic and immunologic progression after the initiation of HAART, discuss methodologic concerns in the study of the response of biomarkers, and update findings obtained in the Multicenter AIDS Cohort Study, which show that CD4 cell count, history of antiretroviral therapy, and age at the time of initiation are independent determinants of response.

Marginal structural models for estimating the effect of highly active antiretroviral therapy initiation on CD4 cell count

The effect of highly active antiretroviral therapy (HAART) on the evolution of CD4-positive T-lymphocyte (CD4 cell) count among human immunodeficiency virus (HIV)-positive participants was estimated using inverse probability-of-treatment-and-censoring (IPTC)-weighted estimation of a marginal structural model. Of 1,763 eligible participants from two US cohort studies followed between 1996 and 2002, 60 percent initiated HAART. The IPTC-weighted estimate of the difference in mean CD4 cell count at 1 year among participants continuously treated versus those never treated was 71 cells/mm3 (95% confidence interval: 47.5, 94.6), which agrees with the reported results of randomized experiments. The corresponding estimate from a standard generalized estimating equations regression model that included baseline and most recent CD4 cell count and HIV type 1 RNA viral load as regressors was 26 cells/mm3 (95% confidence interval: 17.7, 34.3). These results indicate that nonrandomized studies of HIV treatment need to be analyzed with methods (e.g., IPTC-weighted estimation) that, in contrast to standard methods, appropriately adjust for time-varying covariates that are simultaneously confounders and intermediate variables. The 1-year estimate of 71 cells/mm3 was followed by an estimated continued increase of 29 cells/mm3 per year (estimated effect at 6 years: 216 cells/mm3), providing evidence that the large short-term effect found in randomized experiments persists and continues to improve over 6 years.

Characteristics, determinants, and clinical relevance of CD4 T cell recovery to <500 cells/microL in HIV type 1-infected individuals receiving potent antiretroviral therapy

BACKGROUND

The CD4 T cell count recovery in human immunodeficiency virus type 1 (HIV-1)-infected individuals receiving potent antiretroviral therapy (ART) shows high variability. We studied the determinants and the clinical relevance of incomplete CD4 T cell restoration.

METHODS

Longitudinal CD4 T cell count was analyzed in 293 participants of the Swiss HIV Cohort Study who had had a plasma HIV-1 RNA load <1000 copies/mL for > or =5 years. CD4 T cell recovery was stratified by CD4 T cell count 5 years after initiation of ART (> or =500 cells/microL was defined as a complete response, and <500 cells/microL was defined as an incomplete response). Determinants of incomplete responses and clinical events were evaluated using logistic regression and survival analyses.

RESULTS

The median CD4 T cell count increased from 180 cells/microL at baseline to 576 cells/microL 5 years after ART initiation. A total of 35.8% of patients were incomplete responders, of whom 47.6% reached a CD4 T cell plateau <500 cells/microL. Centers for Disease Control and Prevention HIV-1 disease category B and/or C events occurred in 21% of incomplete responders and in 14.4% of complete responders (P>.05). Older age (adjusted odds ratio [aOR], 1.71 per 10-year increase; 95% confidence interval [CI], 1.21-2.43), lower baseline CD4 T cell count (aOR, 0.37 per 100-cell increase; 95% CI, 0.28-0.49), and longer duration of HIV infection (aOR, 2.39 per 10-year increase; 95% CI, 1.19-4.81) were significantly associated with a CD4 T cell count <500 cells/microL at 5 years. The median increases in CD4 T cell count after 3-6 months of ART were smaller in incomplete responders (P<.001) and predicted, in conjunction with baseline CD4 T cell count and age, incomplete response with 80% sensitivity and 72% specificity.

CONCLUSION

Individuals with incomplete CD4 T cell recovery to <500 cells/microL had more advanced HIV-1 infection at baseline. CD4 T cell changes during the first 3-6 months of ART already reflect the capacity of the immune system to replenish depleted CD4 T lymphocytes.

Update on the Virologic and Immunologic Response to Highly Active Antiretroviral Therapy

Highly active antiretroviral therapy (HAART) delays clinical progression by suppressing viral replication, measured by a substantial reduction in HIV RNA, allowing the immune system to reconstitute, measured in most studies by an increase in CD4 cells. These virologic and immunologic consequences do not occur uniformly among HAART users. Markers of HIV disease stage at the time of HAART initiation are critical determinants of the progression while receiving HAART. In this report, we review studies describing the heterogeneous virologic and immunologic progression after the initiation of HAART, discuss methodologic concerns in the study of the response of biomarkers, and update findings obtained in the Multicenter AIDS Cohort Study, which show that CD4 cell count, history of antiretroviral therapy, and age at the time of initiation are independent determinants of response.