Association of tenofovir exposure with kidney disease risk in HIV infection

Vitamin D deficiency aggravates nephrotoxicity, hypertension and dyslipidemia caused by tenofovir: role of oxidative stress and renin-angiotensin system

Vitamin D deficiency (VDD) is prevalent among HIV-infected individuals. Vitamin D has been associated with renal and cardiovascular diseases because of its effects on oxidative stress, lipid metabolism and renin-angiotensin-aldosterone system (RAAS). Tenofovir disoproxil fumarate (TDF), a widely used component of antiretroviral regimens for HIV treatment, can induce renal injury. The aim of this study was to investigate the effects of VDD on TDF-induced nephrotoxicity. Wistar rats were divided into four groups: control, receiving a standard diet for 60 days; VDD, receiving a vitamin D-free diet for 60 days; TDF, receiving a standard diet for 60 days with the addition of TDF (50 mg/kg food) for the last 30 days; and VDD+TDF receiving a vitamin D-free diet for 60 days with the addition of TDF for the last 30 days. TDF led to impaired renal function, hyperphosphaturia, hypophosphatemia, hypertension and increased renal vascular resistance due to downregulation of the sodium-phosphorus cotransporter and upregulation of angiotensin II and AT1 receptor. TDF also increased oxidative stress, as evidenced by higher TBARS and lower GSH levels, and induced dyslipidemia. Association of TDF and VDD aggravated renovascular effects and TDF-induced nephrotoxicity due to changes in the redox state and involvement of RAAS.

Antiretroviral therapy, immune suppression and renal impairment in HIV-positive persons

PURPOSE OF REVIEW

The purpose of this article is to review recent literature on antiretroviral treatment (ART) and immune suppression as risk factors for renal impairment in HIV-positive persons, and to discuss pending research questions within this field.

RECENT FINDINGS

Several individual antiretroviral agents (ARVs) including tenofovir and several protease inhibitors have, in diverse study settings, been associated with renal impairment. Traditional renal risk factors are common among those experiencing adverse renal impairment to ARVs, but do not fully explain why only some develop these effects. Discontinuation of nephrotoxic ARVs is common with declining renal function, but has unknown long-term consequences. Immune suppression is a strong independent risk factor for renal impairment, and ongoing investigations will clarify whether initiating ARVs with nephrotoxic properties at higher CD4 cell counts will have net beneficial effects on renal function.

SUMMARY

With improvements in survival, multiple risk factors have emerged for renal impairment in HIV-positive persons. Although certain ARVs may cause moderate renal impairment, effects on more severe renal impairment remain unresolved. Regular renal function monitoring allow for switching away from nephrotoxic ARVs in case of decreasing function. If such actions prove beneficial higher prevalence of ARV-associated severe renal impairment may emerge in populations without access to regular monitoring.

Tenofovir-induced nephrotoxicity: incidence, mechanism, risk factors, prognosis and proposed agents for prevention

OBJECTIVE

In this study, data regarding epidemiology, risk factors, pathogenesis and outcome of tenofovir-induced nephrotoxicity will be reviewed, and current and future approaches for prevention will be discussed.

METHOD

The data were collected by searching Scopus, PubMed, Medline, Science direct, Clinical trials and Cochrane database systematic reviews. The keywords used as search terms were "Tenofovir", "TDF", "NRTI", "Nephrotoxicity", "Renal failure", "Kidney damage", "HIV" and "AIDS".

RESULTS AND CONCLUSION

Several predisposing factors including elevated baseline SCr, concomitant nephrotoxic medications, low body weight, advanced age, tenofovir disoproxil fumarate (TDF) dose and duration of treatment and lower CD4 cell count were identified as risk factors for development of TDF-induced nephrotoxicity. Cellular accumulation through increased entry from the human organic anion transporters and decreased efflux into tubular lumen is main mechanism of nucleotide analogue antiviral induced nephrotoxicity. Renal function assessment and monitoring at baseline and during TDF treatment are the main approach of prevention of TDF-induced nephrotoxicity. Rosiglitazone may be helpful in patients presenting with TDF-induced nephrotoxicity. Pretreatment with melatonin prevented all known histological changes in proximal tubular mitochondira induced by TDF. Use of antioxidants with mitochondria-targeted properties such as MitoQ or Mito-CP may prevent proximal tubular mitochondrial against TDF damage. Vitamin E, ebselen, lipoic acid, plastoquinone, nitroxides, SOD enzyme mimetics, Szeto-Schiller (SS) peptides, and quercetin are other potential agents for prevention of TDF-induced nephrotoxicity. However, data regarding effectiveness of nephroprotective agents against TDF-induced nephrotoxicity are not conclusive. Before extrapolation of the preclinical evidence to clinical practice, these evidence should be confirmed in future human studies.

A chronic kidney disease risk score to determine tenofovir safety in a prospective cohort of HIV-positive male veterans

OBJECTIVE

Tenofovir disoproxil fumarate is a widely used antiretroviral for HIV infection that has been associated with an increased risk of chronic kidney disease (CKD). Our objective was to derive a scoring system to predict 5-year risk of developing CKD in HIV-infected individuals and to estimate difference in risk associated with tenofovir use.

DESIGN

We evaluated time to first occurrence of CKD (estimated glomerular filtration rate <60 ml/min per 1.73 m(2)) in 21 590 HIV-infected men from the Veterans Health Administration initiating antiretroviral therapy from 1997 to 2010.

METHODS

We developed a point-based score using multivariable Cox regression models. Median follow-up was 6.3 years, during which 2059 CKD events occurred.

RESULTS

Dominant contributors to the CKD risk score were traditional kidney risk factors (age, glucose, SBP, hypertension, triglycerides, proteinuria); CD4(+) cell count was also a component, but not HIV RNA. The overall 5-year event rate was 7.7% in tenofovir users and 3.8% in nonusers [overall adjusted hazard ratio 2.0, 95% confidence interval (CI) 1.8-2.2]. There was a progressive increase in 5-year CKD risk, ranging from less than 1% (zero points) to 16% (≥9 points) in nonusers of tenofovir, and from 1.4 to 21.4% among tenofovir users. The estimated number-needed-to-harm (NNH) for tenofovir use ranged from 108 for those with zero points to 20 for persons with at least nine points. Among tenofovir users with at least 1 year exposure, NNH ranged from 68 (zero points) to five (≥9 points).

CONCLUSION

The CKD risk score can be used to predict an HIV-infected individual's absolute risk of developing CKD over 5 years and may facilitate clinical decision-making around tenofovir use.

Impact of choice of NRTI in first-line antiretroviral therapy: a cohort analysis of stavudine vs. tenofovir

OBJECTIVE

In April 2010, South Africa replaced stavudine with tenofovir in first-line antiretroviral therapy (ART) despite tenofovir's higher cost. We examined treatment outcomes over 24 months amongst patients initiated on tenofovir-based vs. stavudine-based first-line regimens.

METHODS

Prospective cohort analysis of 3940 patients newly initiating either stavudine-based (April 2009 to March 2010) or tenofovir-based (April 2010 to March 2011) ART in Johannesburg, South Africa. Cox proportional hazards models and Fine and Gray's competing risk regression accounting for death were used to model mortality and loss to follow-up, respectively. Linear and log-binomial regression were used to evaluate associations with immunologic response and unsuppressed virus (≥ 400 copies/ml), respectively.

RESULTS

About 1878 patients prescribed tenofovir and 2062 patients prescribed stavudine were included. One hundred and sixty-six (8.8%) tenofovir and 244 (11.8%) stavudine patients died. Three hundred and fifty (18.6%) tenofovir and 379 (18.4%) stavudine patients were lost to follow-up over 24 months on ART. Adjusted regression models showed tenofovir and stavudine were comparable regarding death, loss to follow-up, immunologic response and virologic status.

CONCLUSIONS

We found no difference in mortality, loss to follow-up, immunological and virologic outcomes over the first 24-months on ART associated with tenofovir compared with stavudine.

Screening for decreased glomerular filtration rate and associated risk factors in a cohort of HIV-infected patients in a middle-income country

With the introduction of combined active antiretroviral therapy and the improved survival of HIV-infected patients, degenerative diseases and drug toxicity have emerged as long-term concerns. We studied the prevalence of decreased glomerular filtration rate (GFR) and associated risk factors in a cohort of HIV-infected patients from a middle-income country. Our cross-sectional study included all adult patients who attended an urban outpatient clinic in 2008. GFR was estimated using the CKD-EPI equation. The prevalence ratio (PR) of decreased GFR (defined as <60 mL/min/1.73 m²) was estimated using generalizing linear models assuming a Poisson distribution. We analyzed data from 1,970 patients, of which 82.9% had been exposed to ART. A total of 249 patients (12.6%) had a GFR between 60 and 89 mL/min/1.73 m², 3.1% had a GFR between 30 and 59, 0.3% had a GFR between 15 and 29, and 0.4% had a GFR <15. Decreased GFR was found in only 74 patients (3.8%). In the multivariate regression model, the factors that were independently associated with a GFR below 60 mL/min/1.73 m² were as follows: age ≥50 years (PR = 3.4; 95% CI: 1.7–6.8), diabetes (PR = 2.0; 95% CI: 1.2–3.4), hypertension (PR = 2.0; 95% CI: 1.3–3.2), current CD4+ cell count <350 cells/mm3 (PR = 2.1; 95% CI: 1.3–3.3), past exposure to tenofovir (PR = 4.7; 95% CI: 2.3–9.4) and past exposure to indinavir (PR = 1.7; 95% CI: 1.0–2.8). As in high-income countries, CKD was the predominant form of kidney involvement among HIV-infected individuals in our setting. The risk factors associated with decreased glomerular filtration were broad and included virus-related factors as well as degenerative and nephrotoxic factors. Despite the potential for nephrotoxicity associated with some antiretroviral drugs, in the short-term, advanced chronic renal disease remains very rare.

Changes in renal function associated with oral emtricitabine/tenofovir disoproxil fumarate use for HIV pre-exposure prophylaxis

Objective:

Tenofovir disoproxil fumarate (TDF) pre-exposure prophylaxis decreases sexual acquisition of HIV infection. We sought to evaluate the renal safety of TDF in HIV-uninfected persons.

Design and methods:

The Iniciativa Profilaxis Pre-Exposición (iPrEx) study randomly assigned 2499 HIV-seronegative men and transgender women who have sex with men (MSM) to receive oral daily TDF coformulated with emtricitabine (FTC/TDF) or placebo. Serum creatinine and phosphorus during randomized treatment and after discontinuation were measured, and creatinine clearance (CrCl) was estimated by the Cockcroft–Gault equation. Indicators of proximal renal tubulopathy (fractional excretion of phosphorus and uric acid, urine protein, and glucose) were measured in a substudy.

Results:

There was a small but statistically significant decrease in CrCl from baseline in the active arm, compared to placebo, which was first observed at week 4 (mean change: −2.4 vs. −1.1 ml/min; P = 0.02), persisted through the last on-treatment visit (mean change: +0.3 vs. +1.8 ml/min; P = 0.02), and resolved after stopping pre-exposure prophylaxis (mean change: −0.1 vs. 0.0 ml/min; P = 0.83). The effect was confirmed when stratifying by drug detection. The effect of FTC/TDF on CrCl did not vary by race, age, or history of hypertension. There was no difference in serum phosphate trends between the treatment arms. In the substudy, two participants receiving placebo had indicators of tubulopathy.

Conclusions:

In HIV-seronegative MSM, randomization to FTC/TDF was associated with a very mild nonprogressive decrease in CrCl that was reversible and managed with routine serum creatinine monitoring.

Development of a definition for Rapid Progression (RP) of renal function in HIV-positive persons: the D:A:D study

Background

No consensus exists on how to define abnormally rapid deterioration in renal function (Rapid Progression, RP). We developed an operational definition of RP in HIV-positive persons with baseline estimated glomerular filtration rate (eGFR) >90 ml/min/1.73 m² (using Cockcroft Gault) in the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study from 2004 to 2011.

Methods

Two definitions were evaluated; RP definition A: An average eGFR decline (slope) ≥5 ml/min/1.73 m²/year over four years of follow-up with ≥3 eGFR measurements/year, last eGFR <90 ml/min/1.73 m² and an absolute decline ≥5 ml/min/1.73 m²/year in two consecutive years. RP definition B: An absolute annual decline ≥5 ml/min/1.73 m²/year in each year and last eGFR <90 ml/min/1.73 m². Sensitivity analyses were performed considering two and three years’ follow-up. The percentage with and without RP who went on to subsequently develop incident chronic kidney disease (CKD; 2 consecutive eGFRs <60 ml/min/1.73 m² and 3 months apart) was calculated.

Results

22,603 individuals had baseline eGFR ≥90 ml/min/1.73 m². 108/3655 (3.0%) individuals with ≥4 years’ follow-up and ≥3 measurements/year experienced RP under definition A; similar proportions were observed when considering follow-up periods of three (n=195/6375; 3.1%) and two years (n=355/10756; 3.3%). In contrast under RP definition B, greater proportions experienced RP when considering two years (n=476/10756; 4.4%) instead of three (n=48/6375; 0.8%) or four (n=15/3655; 0.4%) years’ follow-up. For RP definition A, 13 (12%) individuals who experienced RP progressed to CKD, and only (21) 0.6% of those without RP progressed to CKD (sensitivity 38.2% and specificity 97.4%); whereas for RP definition B, fewer RP individuals progressed to CKD.

Conclusions

Our results suggest using three years’ follow-up and at least two eGFR measurements per year is most appropriate for a RP definition, as it allows inclusion of a reasonable number of individuals and is associated with the known risk factors. The definition does not necessarily identify all those that progress to incident CKD, however, it can be used alongside other renal measurements to early identify and assess those at risk of developing CKD. Future analyses will use this definition to identify other risk factors for RP, including the role of antiretrovirals.

Predictors of HIV-associated nephropathy

Renal disease accounts for significant morbidity and mortality in patients with HIV-1 infection. HIV-associated nephropathy (HIVAN) is an important cause of end stage renal disease in this population. Although multiple genetic, clinical, and laboratory characteristics such as Apolipoproetin-1 genetic polymorphism, high viral load, low CD-4 count, nephrotic range proteinuria, and increased renal echogenicity on ultrasound are predictive of HIVAN, kidney biopsy remains the gold standard to make the definitive diagnosis. Current treatment options for HIVAN include initiation of combined active antiretroviral therapy, blockade of the renin-angiotensin system, and steroids. In patients with progression of HIVAN, renal transplant should be pursued as long as their systemic HIV infection is controlled.

Updated US Public Health Service guidelines for the management of occupational exposures to human immunodeficiency virus and recommendations for postexposure prophylaxis

This report updates US Public Health Service recommendations for the management of healthcare personnel (HCP) who experience occupational exposure to blood and/or other body fluids that might contain human immunodeficiency virus (HIV). Although the principles of exposure management remain unchanged, recommended HIV postexposure prophylaxis (PEP) regimens and the duration of HIV follow-up testing for exposed personnel have been updated. This report emphasizes the importance of primary prevention strategies, the prompt reporting and management of occupational exposures, adherence to recommended HIV PEP regimens when indicated for an exposure, expert consultation in management of exposures, follow-up of exposed HCP to improve adherence to PEP, and careful monitoring for adverse events related to treatment, as well as for virologic, immunologic, and serologic signs of infection. To ensure timely postexposure management and administration of HIV PEP, clinicians should consider occupational exposures as urgent medical concerns, and institutions should take steps to ensure that staff are aware of both the importance of and the institutional mechanisms available for reporting and seeking care for such exposures. The following is a summary of recommendations: (1) PEP is recommended when occupational exposures to HIV occur; (2) the HIV status of the exposure source patient should be determined, if possible, to guide need for HIV PEP; (3) PEP medication regimens should be started as soon as possible after occupational exposure to HIV, and they should be continued for a 4-week duration; (4) new recommendation-PEP medication regimens should contain 3 (or more) antiretroviral drugs (listed in Appendix A ) for all occupational exposures to HIV; (5) expert consultation is recommended for any occupational exposures to HIV and at a minimum for situations described in Box 1 ; (6) close follow-up for exposed personnel ( Box 2 ) should be provided that includes counseling, baseline and follow-up HIV testing, and monitoring for drug toxicity; follow-up appointments should begin within 72 hours of an HIV exposure; and (7) new recommendation-if a newer fourth-generation combination HIV p24 antigen-HIV antibody test is utilized for follow-up HIV testing of exposed HCP, HIV testing may be concluded 4 months after exposure ( Box 2 ); if a newer testing platform is not available, follow-up HIV testing is typically concluded 6 months after an HIV exposure.

Antiretrovirals and the kidney in current clinical practice: renal pharmacokinetics, alterations of renal function and renal toxicity

Assessment of renal function in HIV-positive patients is of increasing importance in the context of ageing and associated comorbidities. Exposure to nephrotoxic medications is widespread, and several commonly used antiretroviral drugs have nephrotoxic potential. Moreover, specific antiretrovirals inhibit renal tubular transporters resulting in the potential for drug-drug interactions as well as increases in serum creatinine concentrations, which affect estimates of glomerular filtration rate in the absence of changes in actual glomerular filtration rate. This review explores the effects of antiretroviral therapy on the kidney and offers an understanding of mechanisms that lead to apparent and real changes in renal function.

Estimating the causal effects of cumulative treatment episodes for adolescents using marginal structural models and inverse probability of treatment weighting

BACKGROUND

Substance use treatment is rarely a one-time event for individuals with substance use disorders. Sustained reductions in substance use and its related symptoms may result from multiple treatment episodes.

METHODS

We use a marginal structural model with inverse-probability-of-treatment weighting to estimate the causal effects of cumulative treatment experiences over a period of 9 months on drug use at the end of 1-year among 2870 adolescents receiving care in community-based treatment settings. During the 9 months, adolescents move in and out of outpatient and residential treatment with periods where they only receive biological drug screening (BDS) or no treatment at all. The use of inverse-probability-of-treatment weighting reduces confounding bias due to observed baseline and time-varying measures over the course of follow-up; weights were estimated using generalized boosted models.

RESULTS

Each additional period of treatment (representing at least one day, 1 session, or 1 BDS during the 90 day period between follow-up visits) yielded reductions in average substance use frequency at 1-year relative to no treatment during the 90-day period. For residential treatment it was a 16% decrease (95% CI=-27%, -7%), for outpatient treatment it was a 9% decrease (95% CI=-18%, -0%), and for BDS (with no additional outpatient or residential treatment) it was an 11% decrease (95% CI=-20%, -3%).

CONCLUSIONS

Using robust statistical methods, we find promising (albeit preliminary) evidence that additional periods of outpatient and residential treatment, as well as biological drug screening, lead to reductions in substance use outcomes at one year.

Incomplete reversibility of estimated glomerular filtration rate decline following tenofovir disoproxil fumarate exposure

Background. Tenofovir disoproxil fumarate (TDF) has been linked to renal impairment, but the extent to which this impairment is reversible is unclear. We aimed to investigate the reversibility of renal decline during TDF therapy.

Methods. Cox proportional hazards models assessed factors associated with discontinuing TDF in those with an exposure duration of >6 months. In those who discontinued TDF therapy, linear piecewise regression models estimated glomerular filtration rate (eGFR) slopes before initiation of, during, and after discontinuation of TDF therapy. Factors associated with not achieving eGFR recovery 6 months after discontinuing TDF were assessed using multivariable logistic regression.

Results. We observed declines in the eGFR during TDF exposure (mean slopes, −15.7 mL/minute/1.73 m²/year [95% confidence interval {CI}, −20.5 to −10.9] during the first 3 months and −3.1 mL/minute/1.73 m²/year [95% CI, −4.6 to −1.7] thereafter) and evidence of eGFR increases following discontinuation of TDF therapy (mean slopes, 12.5 mL/minute/1.73 m²/year [95% CI, 8.9–16.1] during the first 3 months and 0.8 mL/minute/1.73 m²/year [95% CI, .1–1.5] thereafter). Following TDF discontinuation, 38.6% of patients with a decline in the eGFR did not experience recovery. A higher eGFR at baseline, a lower eGFR after discontinuation of TDF therapy, and more-prolonged exposure to TDF were associated with an increased risk of incomplete recovery 6 months after discontinuation of TDF therapy.

Conclusions. This study shows that a decline in the eGFR during TDF therapy was not fully reversible in one third of patients and suggests that prolonged TDF exposure at a low eGFR should be avoided.

Effect of baseline renal function on tenofovir-containing antiretroviral therapy outcomes in Zambia

BACKGROUND

Although tenofovir disoproxil fumarate (TDF) use has increased as part of first-line antiretroviral therapy (ART) across sub-Saharan Africa, renal outcomes among patients receiving TDF remain poorly understood. We assessed changes in renal function and mortality in patients starting TDF- or non-TDF-containing ART in Lusaka, Zambia.

METHODS

We included patients aged ≥16 years who started ART from 2007 onward, with documented baseline weight and serum creatinine. Renal dysfunction was categorized as mild (estimated glomerular filtration rate [eGFR], 60-89 mL/min), moderate (30-59 mL/min), or severe (<30 mL/min) according to the chronic kidney disease-epidemiology (CKD-EPI) formula. Differences in eGFR during ART were analyzed using linear mixed-effect models. The odds of developing moderate or severe eGFR decrease and mortality were assessed using logistic and competing risk regression, respectively.

RESULTS

We included 62 230 adults, of which 38 716 (62.2%) initiated a TDF-based regimen. The proportion with moderate or severe renal dysfunction at baseline was lower in the TDF than in the non-TDF group (1.9% vs 4.0%). Among patients with no or mild renal dysfunction, those receiving TDF were more likely to develop moderate (adjusted odds ratio, 3.11; 95% confidence interval, 2.52-3.87) or severe (2.43; 1.80-3.28) eGFR decrease, although the incidence in such episodes was low. Among patients with moderate or severe renal dysfunction at baseline, renal function improved independently of ART regimen, and mortality rates were similar in both treatment groups.

CONCLUSIONS

TDF use did not attenuate renal function recovery or increase the mortality rate in patients with renal dysfunction. Further studies are needed to determine the role of routine renal function monitoring before and during ART use in Africa.

The changing epidemiology of HIV-related chronic kidney disease in the era of antiretroviral therapy

The epidemiology of kidney disease in HIV-infected individuals has changed significantly since the introduction of combination antiretroviral therapy (cART) in the mid 1990s. HIV-associated nephropathy (HIVAN), an aggressive form of collapsing focal segmental glomerulosclerosis (FSGS) caused by direct HIV infection of the kidney in a genetically susceptible host, emerged early in the HIV epidemic as a leading cause of end-stage renal disease. With the widespread use of cART, HIVAN is increasingly rare in populations with access to care, and the spectrum of HIV-related chronic kidney disease now reflects the growing burden of comorbid disease in the aging HIV population. Nonetheless, available data suggest that both HIV infection and cART nephrotoxicity continue to contribute to the increased risk of chronic kidney disease in HIV-infected individuals in the United States and Europe. Despite the genetic susceptibility to HIVAN in individuals of West African descent, limited data are available to define the prevalence and spectrum of HIV-related kidney disease in sub-Saharan Africa, which is home to two-thirds of the world's HIV population. In this mini-review, we characterize the changing epidemiology of HIV-related chronic kidney disease in Western nations and in sub-Saharan Africa.

Phase I/II study of the pharmacokinetics, safety and antiretroviral activity of tenofovir alafenamide, a new prodrug of the HIV reverse transcriptase inhibitor tenofovir, in HIV-infected adults

BACKGROUND

Tenofovir alafenamide (formerly GS-7340) is a new oral prodrug of tenofovir, a nucleotide analogue that inhibits HIV-1 reverse transcription. Unlike the currently marketed tenofovir prodrug, tenofovir disoproxil fumarate, tenofovir alafenamide is stable in plasma and then rapidly converted into tenofovir once inside cells.

METHODS

The pharmacokinetics, safety and antiviral activity of 40 or 120 mg of tenofovir alafenamide compared with 300 mg of tenofovir disoproxil fumarate when administered as monotherapy once daily for 14 days in HIV-1-infected, treatment-naive subjects was studied.

RESULTS

Administration of 40 mg of tenofovir alafenamide for 14 days resulted in lower tenofovir Cmax (13 versus 207 ng/mL) and lower systemic exposures (AUC0-t, 383 versus 1810 ng · h/mL) compared with subjects who received tenofovir disoproxil fumarate. There were higher intracellular tenofovir concentrations within peripheral blood mononuclear cells with both 40 mg of tenofovir alafenamide (8.2 μM) and 120 mg of tenofovir alafenamide (16.9 μM) compared with 300 mg of tenofovir disoproxil fumarate (0.9 μM). The most commonly observed adverse events were headache, nausea and flatulence, which occurred similarly across the three groups. After 14 days, the mean changes in HIV-1 RNA were -0.94 log₁₀copies/mL for the tenofovir disoproxil fumarate group, -1.57 log₁₀ copies/mL for the 40 mg of tenofovir alafenamide group and -1.71 log₁₀ copies/mL for the 120 mg of tenofovir alafenamide group. The mean first-phase HIV-1 RNA decay slopes were -0.36, -0.63 and -0.64 for the tenofovir disoproxil fumarate group, the 40 mg of tenofovir alafenamide group and the 120 mg of tenofovir alafenamide group, respectively. No resistance mutations to either tenofovir alafenamide or tenofovir disoproxil fumarate were detected.

CONCLUSIONS

Tenofovir alafenamide, a new once-daily oral prodrug of tenofovir, showed more potent anti-HIV-1 activity and higher intracellular tenofovir levels compared with tenofovir disoproxil fumarate, while maintaining lower plasma tenofovir exposure at 40 mg with good tolerability over 14 days of monotherapy.

Application of marginal structural models in pharmacoepidemiologic studies: a systematic review

PURPOSE

We systematically reviewed pharmacoepidemiologic studies published in 2012 that used inverse probability weighted (IPW) estimation of marginal structural models (MSM) to estimate the effect from a time-varying treatment.

METHODS

Potential studies were retrieved through a citation search within Web of Science and a keyword search within PubMed. Eligibility of retrieved studies was independently assessed by at least two reviewers. One reviewer performed data extraction, and a senior epidemiologist confirmed the extracted information for all eligible studies.

RESULTS

Twenty pharmacoepidemiologic studies were eligible for data extraction. The majority of reviewed studies did not report whether the positivity assumption was checked. Six studies performed intention-to-treat analyses, but none of them reported adherence levels after treatment initiation. Eight studies chose an as-treated analytic strategy, but only one of them reported modeling the multiphase of treatment use. Almost all studies performing as-treated analyses chose the most recent treatment status as the functional form of exposure in the outcome model. Nearly half of the studies reported that the IPW estimate was substantially different from the estimate derived from a standard regression model.

CONCLUSIONS

The use of IPW method to control for time-varying confounding is increasing in medical literature. However, reporting of the application of the technique is variable and suboptimal. It may be prudent to develop best practices in reporting complex methods in epidemiologic research.

Predictors of advanced chronic kidney disease and end-stage renal disease in HIV-positive persons

OBJECTIVES

Whilst several antiretroviral drugs have been associated with moderate chronic kidney disease (CKD), their contribution to advanced CKD and end-stage renal disease (ESRD) remain unknown.

DESIGN

D:A:D participants with at least three estimated glomerular filtration rates (eGFR) after February 2004 were followed until the first of advanced CKD (confirmed eGFR ≤ 30 ml/min, ≥3 months apart), ESRD (dialysis ≥3 months/ transplantation), 6 months after last visit or February 2012.

METHODS

Poisson regression was used to assess risk factors for advanced CKD/ESRD including exposure to potential nephrotoxic antiretroviral drugs and antiretroviral drug discontinuation rates according to latest eGFR.

RESULTS

Among 35 192 persons contributing 200 119 person years of follow-up (PYFU), 135 (0.4%) developed advanced CKD (n = 114)/ESRD (n = 21); incidence rate = 0.67 [95% confidence interval (CI), 0.56-0.79]/1000 PYFU. Tenofovir (TDF) was particularly frequently discontinued as eGFR declined. After adjustment, those previously exposed but currently off TDF had similar advanced CKD/ESRD rate ratios compared with those unexposed [1.00 (95% CI, 0.66-1.51)], while those currently on TDF had reduced rates [0.23 (95% CI, 0.13-0.41)]. No consistent associations with other antiretroviral drugs were seen. Results were robust after time-lagging antiretroviral drug exposure, stratifying by baseline eGFR, and allowing for competing risks. Other predictors were diabetes, hypertension, baseline eGFR, smoking and current CD4 cell count. The incidence rate in nonsmokers with baseline eGFR > 60 and no diabetes or hypertension was 0.16 (95% CI 0.09-0.26)/1000 PYFU.

CONCLUSION

Neither current nor recent antiretroviral drug use predicted advanced CKD/ESRD during 6 years median follow-up in a large, heterogenenous and primarily white cohort. TDF discontinuation rates increased with decreasing eGFR, leaving a selected group still on TDF at lower advanced CKD/ESRD risk. Traditional renal risk factors and current CD4 cell count were the strongest advanced CKD/ESRD predictors.

Common clinical conditions - age, low BMI, ritonavir use, mild renal impairment - affect tenofovir pharmacokinetics in a large cohort of HIV-infected women

OBJECTIVE

Tenofovir is used commonly in HIV treatment and prevention settings, but factors that correlate with tenofovir exposure in real-world settings are unknown.

DESIGN

Intensive pharmacokinetic studies of tenofovir in a large, diverse cohort of HIV-infected women over 24 h at steady state were performed and factors that influenced exposure [assessed by areas under the concentration-time curves (AUCs)] identified.

METHODS

HIV-infected women (n = 101) on tenofovir-based therapy underwent intensive 24-h pharmacokinetic sampling. Data on race/ethnicity, age, exogenous steroid use, menstrual cycle phase, concomitant medications, recreational drugs and/or tobacco, hepatic and renal function, weight, and BMI were collected. Multivariable models using forward stepwise selection identified factors associated with effects on AUC. Glomerular filtration rates (GFRs) prior to starting tenofovir were estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation using both creatinine and cystatin-C measures.

RESULTS

The median (range) of tenofovir AUCs was 3350 (1031-13 911) ng × h/ml. Higher AUCs were associated with concomitant ritonavir use (1.33-fold increase, P = 0.002), increasing age (1.21-fold increase per decade, P = 0.0007), and decreasing BMI (1.04-fold increase per 10% decrease in BMI). When GFR was calculated using cystatin-C measures, mild renal insufficiency prior to tenofovir initiation was associated with higher subsequent exposure (1.35-fold increase when pre-tenofovir GFR <70 ml/min, P = 0.0075).

CONCLUSION

Concomitant ritonavir use, increasing age, decreasing BMI, and lower GFR prior to tenofovir initiation as estimated by cystatin C were all associated with elevated tenofovir exposure in a diverse cohort of HIV-infected women. Clinicians treating HIV-infected women should be aware of common clinical conditions that affect tenofovir exposure when prescribing this medication.

Renal Function Recovery and HIV Viral Suppression Following Tenofovir Discontinuation for Renal Impairment

BACKGROUND

Tenofovir associated nephrotoxicity (TDFN) is well recognized. This study describes the trend of renal function recovery and virologic consequences after cessation of tenofovir (TDF) for suspected TDFN.

METHODS

This was a retrospective chart review of 241 patients who underwent HLA-B*5701 allele testing between January 2007-December 2010. Demographics and clinical characteristics were compared at baseline, 3, 6, and 12 month between patients that continued and discontinued TDF. Factors associated with renal function recovery were assessed by multivariable logistic regression.

RESULTS

Eighty patients were identified with TDFN; 84% male, 74% African American (AA) with a median age of 55 years, and median length of TDF use for 122 weeks. Renal recovery at 12 months differed in those who stopped versus (vs.) continued TDF (83% vs. 57% p=0.03). In a crude analysis, baseline chronic kidney disease was negatively associated with renal recovery (p=0.01). An adjusted analysis showed that those who stopped TDF had 3.76 higher odds of renal recovery compared to those who did not stop TDF (95% CI: 1.26-11.27, p=0.02). There were no significant differences in virologic response after switching TDF to an alternative agent.

CONCLUSION

In this mostly AA male population with suspected TDFN, discontinuation of TDF was strongly associated with renal function recovery without affecting viral suppression.

Randomized, placebo-controlled single-ascending-dose study to evaluate the safety, tolerability and pharmacokinetics of the HIV nucleoside reverse transcriptase inhibitor, BMS-986001, in healthy subjects

The objectives of this study were to evaluate the safety, tolerability and pharmacokinetics (PK) of BMS-986001 as a single oral dose in healthy male subjects. Sixty-four healthy male subjects were randomized to receive a single dose of BMS-986001 or placebo in this single-blind, placebo-controlled, sequential ascending-dose study. There were eight treatment groups (10, 30, 100, 300, 600, and 900 mg fed; and 100 and 300 mg fasted) of eight subjects each (BMS-986001 n = 6/placebo n = 2). BMS-986001 was well tolerated, with no serious adverse events (AEs), deaths, or discontinuations due to AEs reported. AEs were experienced by 14.6% of subjects receiving BMS-986001; however, these did not appear to be dose related and were not considered to be related to study drug. BMS-986001 was rapidly absorbed and exhibited a linear dose-exposure relationship across the dose range studied. PK appeared similar whether administered with or without food. Administration of BMS-986001 as a single dose was generally safe and well tolerated. A linear dose-exposure relationship was seen across all doses studied, with no apparent food effect. Further clinical development is warranted.

Low body weight in females is a risk factor for increased tenofovir exposure and drug-related adverse events

Treatment with tenofovir sometimes leads to non-reversible kidney and/or bone diseases. Factors associated with these drug-related adverse events are poorly characterized. Our objective was to investigate such factors in patients treated long term with daily tenofovir. One-hundred Caucasian HIV-positive patients with basal creatinine clearance >80 mL/min treated with tenofovir for at least 6 months and with at least one assessment of tenofovir plasma trough concentrations were considered. Tenofovir-associated adverse events were defined as the appearance of pathological proteinuria, worsening of renal function or bone demineralization. By multivariate regression analysis, we found that serum creatinine (p = 0.003) and body weight (p = 0.002) were the factors independently associated with plasma tenofovir concentrations. In particular, women with body weight<50 kg had significantly higher plasma tenofovir concentrations than those weighting >50 Kg (160±93 vs.71±52 ng/mL, p<0.001). High tenofovir plasma trough concentrations and the age of the patients were independently associated with the development of drug-related kidney and bone toxicity. In this retrospective study we have shown that HIV-infected women with low body weight are at risk to be exposed to high tenofovir plasma trough concentrations, ultimately resulting in a significant hazard to develop long-term tenofovir complications.

Increases in regimen durability associated with the introduction of tenofovir at a large public-sector clinic in Johannesburg, South Africa

INTRODUCTION

In April 2010, tenofovir replaced stavudine in public-sector first-line antiretroviral therapy (ART) in South Africa. The association of tenofovir with fewer side effects and toxicities compared to stavudine could translate to increased durability of tenofovir-based regimens. We evaluated changes over time in regimen durability at the Themba Lethu Clinic, Johannesburg, South Africa.

METHODS

This was a cohort analysis of treatment-naïve, non-pregnant adult patients initiated on ART between April 2004 and December 2011. First-line ART regimens before April 2010 consisted of stavudine or zidovudine with lamivudine and either efavirenz or nevirapine. Tenofovir was substituted for stavudine after April 2010. We evaluated the frequency and type of single-drug substitutions (excluding switches to second-line therapy). Cox models were used to evaluate the association of ART initiation year and antiretroviral drug type with single-drug substitutions in the first 12 months on treatment.

RESULTS

One thousand nine hundred and sixty-four (10%) substitutions occurred amongst 19,699 patients. Excluding 2004 (year of treatment roll-out), before 2010 one-year single-drug substitutions ranged from 10.0 to 13.1%. In 2011, well after integration of tenofovir, substitutions decreased to 5.6%. Single-drug substitution was lowest amongst patients on tenofovir (5.1%) versus zidovudine (11.3%), 30 mg stavudine (10.5%) or 40 mg stavudine (14.4%). Adjusted Cox models showed that patients initiating treatment between 2005 and 2010 (vs. 2011) had a twofold increased hazard of single-drug substitution, while those on zidovudine or stavudine had a two to threefold increase in single-drug substitution versus tenofovir patients in the first 12 months on ART.

CONCLUSIONS

The decline in single-drug substitutions is associated with the introduction of tenofovir. Tenofovir use could improve regimen durability and treatment outcomes in resource-limited settings.

Plasma apolipoprotein L1 levels do not correlate with CKD

Polymorphisms in APOL1 are associated with CKD, including HIV-related CKD, in individuals of African ancestry. The apolipoprotein L1 (APOL1) protein circulates and is localized in kidney cells, but the contribution of APOL1 location to CKD pathogenesis is unclear. We examined associations of plasma APOL1 levels with plasma cytokine levels, dyslipidemia, and APOL1 genotype in a nested case-control study (n=270) of HIV-infected African Americans enrolled in a multicenter prospective observational study. Patients were designated as having CKD when estimated GFR (eGFR) decreased to <60 ml/min per 1.73 m(2) (eGFR<60 cohort) or protein-to-creatinine ratios became >3.5 g/g (nephrotic proteinuria cohort). Circulating APOL1 levels did not associate with APOL1 genotype, CKD status, or levels of proinflammatory cytokines, but did correlate with fasting cholesterol, LDL cholesterol, and triglyceride levels. At ascertainment, CKD-associated polymorphisms (risk variants) in APOL1 associated with the eGFR<60 cohort, but not the nephrotic-range proteinuria cohort. Of note, in both the eGFR<60 and nephrotic proteinuria cohorts, CKD cases with two APOL1 risk variants had significant declines in eGFR over a median of 4 years compared with individuals with one or no risk variants. APOL1 risk genotype was not associated with changes in proteinuria. Higher circulating proinflammatory cytokine levels were independently associated with CKD but not APOL1 genotype. In conclusion, the function of variant APOL1 proteins derived from circulation or synthesized in the kidney, but not the level of circulating APOL1, probably mediates APOL1-associated kidney disease in HIV-infected African Americans.

The end of AIDS: HIV infection as a chronic disease

The success of antiretroviral therapy has led some people to now ask whether the end of AIDS is possible. For patients who are motivated to take therapy and who have access to lifelong treatment, AIDS-related illnesses are no longer the primary threat, but a new set of HIV-associated complications have emerged, resulting in a novel chronic disease that for many will span several decades of life. Treatment does not fully restore immune health; as a result, several inflammation-associated or immunodeficiency complications such as cardiovascular disease and cancer are increasing in importance. Cumulative toxic effects from exposure to antiretroviral drugs for decades can cause clinically-relevant metabolic disturbances and end-organ damage. Concerns are growing that the multimorbidity associated with HIV disease could affect healthy ageing and overwhelm some health-care systems, particularly those in resource-limited regions that have yet to develop a chronic care model fully. In view of the problems inherent in the treatment and care for patients with a chronic disease that might persist for several decades, a global effort to identify a cure is now underway.

Is HIV a model of accelerated or accentuated aging?

BACKGROUND

Antiretroviral therapy has reduced the incidence of adverse events and early mortality in HIV-infected persons. Despite these benefits, important comorbidities that increase with age (eg, diabetes, cardiovascular disease, cancer, liver disease, and neurocognitive impairment) are more prevalent in HIV-infected persons than in HIV-uninfected persons at every age, and geriatric syndromes such as falls and frailty occur earlier in HIV-infected persons. This raises a critical research question: Does HIV accelerate aging through pathways and mechanisms common to the aging process or is HIV simply an additional risk factor for a wide number of chronic conditions, thus accentuating aging?

METHODS

Extensive literature review.

RESULTS

The purpose of this review is to briefly outline the evidence that age-related clinical syndromes are exacerbated by HIV, examine the ways in which HIV is similar, and dissimilar from natural aging, and assess the validity of HIV as a model of premature aging. Specific biomarkers of aging are limited in HIV-infected hosts and impacted by antiretroviral therapy, and a high rate of modifiable life style confounders (eg, smoking, substance abuse, alcohol) and coinfections (eg, hepatitis) in HIV-infected participants.

CONCLUSIONS

There is a need for validated biomarkers of aging in the context of HIV. Despite these differences, welldesigned studies of HIV-infected participants are likely to provide new opportunities to better understand the mechanisms that lead to aging and age-related diseases.

BMS-986001, an HIV nucleoside reverse transcriptase inhibitor, does not degrade mitochondrial DNA in long-term primary cultures of cells isolated from human kidney, muscle, and adipose tissue

Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) remain the cornerstone of HIV treatment; however, they are associated with toxicities attributed in part to inhibition of mitochondrial DNA (mtDNA) polymerase γ. In this study, we compared the in vitro toxicity profiles of structurally similar NRTIs (BMS-986001 to stavudine and tenofovir to adefovir) that differ by the presence of an acetylene or methyl group, respectively. Primary cultures of human renal proximal tubule epithelium, skeletal muscle myotubes, and differentiated adipocytes were exposed to the NRTIs at the maximum concentration (Cmax) reported for the clinically approved dose (investigational dose for BMS-986001, 600 mg) and a high equimolar concentration (200 μM) for 19 days. After 19 days, BMS-986001 did not significantly decrease mtDNA or cell protein at either concentration in any cell line. In contrast, stavudine significantly decreased mtDNA in all cultures (1.5- to 2.5-fold) (except at Cmax in renal cells) and cell protein in renal cells (1.4- to 2.4-fold). By day 19, at 200 μM, tenofovir significantly reduced mtDNA in adipocytes (1.9-fold) and adefovir significantly decreased mtDNA in all cultures (3.7- to 10.2-fold); however, no significant reduction in mtDNA was observed at Cmax in any cell line. Adefovir also significantly reduced cell protein at both concentrations in renal cells (2.2- to 2.8-fold) and at 200 μM in muscle cells (2.0-fold). In conclusion, BMS-986001 and tenofovir were considerably less cytotoxic than their respective structural analogs, demonstrating that small structural differences can contribute to significant differences in toxicity.

An investigation of the pattern of kidney injury in HIV-positive persons exposed to tenofovir disoproxil fumarate: an examination of a large population database (MHRA database)

The potential for tenofovir to cause a range of kidney syndromes has been established from mechanistic and randomised clinical trials. However, the exact pattern of kidney involvement is still uncertain. We undertook a descriptive analysis of Yellow Card records of 407 HIV-positive persons taking tenofovir disoproxil fumarate (TDF) as part of their antiretroviral therapy regimen and submitted to the Medicines and Healthcare Products Regulatory Agency (MHRA) with suspected kidney adverse effects. Reports that satisfy defined criteria were classified as acute kidney injury, kidney tubular dysfunction and Fanconi syndrome. Of the 407 Yellow Card records analysed, 106 satisfied criteria for TDF-related kidney disease, of which 53 (50%) had features of kidney tubular dysfunction, 35 (33%) were found to have features of glomerular dysfunction and 18 (17%) had Fanconi syndrome. The median TDF exposure was 316 days (interquartile range 120–740). The incidence of hospitalisation for TDF kidney adverse effects was high, particularly amongst patients with features of Fanconi syndrome. The pattern of kidney syndromes in this population series mirrors that reported in randomised clinical trials. Cessation of TDF was associated with complete restoration of kidney function in up half of the patients in this report.

Tenofovir effect on the kidneys of HIV-infected patients: a double-edged sword?

Tenofovir disoproxil fumarate (TDF), the first nucleotidic inhibitor of HIV reverse transcription, became available in 2001. It has been extensively used worldwide and is now the most prescribed antiretroviral (ARV) drug. Its high antiviral activity and favorable metabolic profile are responsible for its success. Furthermore, TDF has been associated with other ARVs to form new combined antiretroviral treatments in only one tablet once-a-day, which increases treatment adherence. Fears of potential nephrotoxicity that tenofovir would have in common with two other drugs from the same family (adefovir, used to treat hepatitis B, and cidofovir, used to treat cytomegalovirus infections) were alleviated by the early clinical trials. Yet, in 2001, the first case of TDF-induced acute nephrotoxicity was published. Numerous cases have been published since then, and it is now established that TDF presents a tubular toxicity risk. Some facilitating factors have been identified, such as co-prescription of didanosine or boosted protease inhibitor, preexisting CKD, low body weight, and associated diabetes mellitus. Conversely, whether TDF is nephrotoxic in the long term is a highly debated question. Some studies suggest a decreased GFR when TDF is prescribed for a long period, while others indicate that TDF is safe for the kidneys even after many years of use. Here we review the differences in patient characteristics, study designs, and measured outcomes that can possibly explain these conflicting findings. We conclude with rational recommendation for appropriate TDF prescription.

A review of cardiovascular and renal function monitoring: a consideration of older adults with HIV

The prevalence of human immunodeficiency virus (HIV) infection in older and elderly adults is significant worldwide. This population poses new challenges and opportunities in the management of HIV. In addition to the risks affecting HIV patients of all ages, including risk of opportunistic infection and medication resistance, age-related changes in physiology, higher comorbidity burdens, increased use of medications, and potential adverse drug reactions to HIV medications all factor into the care of older adults with HIV. The risk and progression of cardiovascular and renal comorbidities may be higher in the older adult HIV population and in patients taking specific HIV medications. Understanding these risks is essential when managing a new type of patient: the older adult with HIV.

Comparisons of creatinine and cystatin C for detection of kidney disease and prediction of all-cause mortality in HIV-infected women

BACKGROUND

Cystatin C could improve chronic kidney disease (CKD) classification in HIV-infected women relative to serum creatinine.

DESIGN

Retrospective cohort analysis.

METHODS

Cystatin C and creatinine were measured from specimens taken and stored during the 1999-2000 examination among 908 HIV-infected participants in the Women's Interagency HIV study (WIHS). Mean follow-up was 10.2 years. Predictors of differential glomerular filtration rate (GFR) estimates were evaluated with multivariable linear regression. The associations of baseline categories (<60, 60-90, and >90 ml/min per 1.73 m) of creatinine estimated GFR (eGFRcr), cystatin C eGFR (eGFRcys), and combined creatinine-cystatin C eGFR (eGFRcr-cys) with all-cause mortality were evaluated using multivariable Cox regression. The net reclassification index (NRI) was calculated to evaluate the effect of cystatin C on reclassification of CKD staging.

RESULTS

CKD risk factors were associated with lower eGFRcys and eGFRcr-cys values compared with eGFRcr. Relative to eGFR more than 90, the eGFR less than 60 category by eGFRcys (Adjusted hazard ratio: 2.56; 95% confidence interval: 1.63-4.02), eGFRcr-cys (3.11; 1.94-5.00), and eGFRcr (2.34; 1.44-3.79) was associated with increased mortality risk. However, the eGFR 60-90 category was associated with increased mortality risk for eGFRcys (1.80; 1.28-2.53) and eGFRcr-cys (1.91; 1.38-2.66) but not eGFRcr (1.20; 0.85-1.67). The overall NRI for mortality was 26% when reclassifying from eGFRcr to eGFRcys (P < 0.001) and was 20% when reclassifying from eGFRcr to eGFRcr-cys (P < 0.001).

CONCLUSION

The addition of cystatin C may improve mortality risk prediction by stages of kidney function relative to creatinine. CKD risk factors are associated with an overestimate of GFR by serum creatinine relative to cystatin C.

Evolution of glomerular filtration rate in HIV-infected, HIV-HBV-coinfected and HBV-infected patients receiving tenofovir disoproxil fumarate

We aimed to compare the evolution of estimated glomerular filtration rate (eGFR) in HIV-, HIV-HBV- and HBV-infected patients treated with tenofovir disoproxil fumarate (TDF). Three groups of patients receiving TDF > 12 months were recruited: 194 HIV-infected patients, 85 HIV-HBV-coinfected patients and 50 HBV-infected patients. eGFR was estimated using the Modification of the Diet in Renal Disease (MDRD) equation. Multivariate regression models were constructed to estimate factors associated with eGFR decrease from baseline. A total of 329 patients were studied. Median follow-up was 2.7 years. Median eGFR decrease was -4.9 (-16.6 to +7.2) mL/min/1.73 m(2) . After multivariate stepwise regression analysis, age (P = 0.0002), non-African origin (P < 0.0001), baseline eGFR (P < 0.0001) and TDF duration (P = 0.02) were associated with eGFR decrease in the whole population, while hypertension, diabetes and type of infection were not. Age (P < 0.0001), non-African origin (P = 0.0004), baseline eGFR (P < 0.0001) and TDF duration (P = 0.007) remained associated with eGFR decline in HIV and HIV-HBV-infected patients, while other variables including HIV risk factor, CDC stage, CD4 and HIV-RNA levels were not. Age (P = 0.03), non-African origin (P = 0.004), baseline eGFR (P < 0.0001) and baseline HBV-DNA > 2000 IU/mL (P = 0.04) were associated with eGFR decline in HBV and HIV-HBV-infected patients, while other variables including HBV risk factor and fibrosis stage were not. Estimated glomerular filtration rate decline under TDF therapy appears mainly associated with older age, non-African origin, higher baseline eGFR and longer TDF administration but not with the type of viral infection. Regular follow-up of renal function, especially tubular function is recommended during TDF therapy.

Estimating kidney function in HIV-infected adults in Kenya: comparison to a direct measure of glomerular filtration rate by iohexol clearance

Background

More than two-thirds of the world's HIV-positive individuals live in sub-Saharan Africa, where genetic susceptibility to kidney disease is high and resources for kidney disease screening and antiretroviral therapy (ART) toxicity monitoring are limited. Equations to estimate glomerular filtration rate (GFR) from serum creatinine were derived in Western populations and may be less accurate in this population.

Methods

We compared results from published GFR estimating equations with a direct measure of GFR by iohexol clearance in 99 HIV-infected, ART-naïve Kenyan adults. Iohexol concentration was measured from dried blood spots on filter paper. The bias ratio (mean of the ratio of estimated to measured GFR) and accuracy (percentage of estimates within 30% of the measured GFR) were calculated.

Results

The median age was 35 years, and 60% were women. The majority had asymptomatic HIV, with median CD4+ cell count of 355 cells/mm³. Median measured GFR was 115 mL/min/1.73 m². Overall accuracy was highest for the Chronic Kidney Disease Epidemiology Consortium (CKD-EPI) equation. Consistent with a prior report, bias and accuracy were improved by eliminating the coefficient for black race (85% of estimates within 30% of measured GFR). Accuracy of all equations was poor in participants with GFR 60–90 mL/min/1.73 m² (<65% of estimates within 30% of measured GFR), although this subgroup was too small to reach definitive conclusions.

Conclusions

Overall accuracy was highest for the CKD-EPI equation. Eliminating the coefficient for race further improved performance. Future studies are needed to determine the most accurate GFR estimate for use in individuals with GFR <90 mL/min/1.73 m², in whom accurate estimation of kidney function is important to guide drug dosing. Direct measurement of GFR by iohexol clearance using a filter paper based assay is feasible for research purposes in resource-limited settings, and could be used to develop more accurate GFR estimates in African populations.

Switching tenofovir/emtricitabine plus lopinavir/r to raltegravir plus Darunavir/r in patients with suppressed viral load did not result in improvement of renal function but could sustain viral suppression: a randomized multicenter trial

Background

Whether tenofovir nephrotoxicity is reversible after its withdrawal is unknown. Furthermore, there are no data on the viral efficacy of raltegravir (RAL) plus ritonavir-boosted Darunavir (DRV/r) in patients with suppressed viral load.

Methods

This multicenter, randomized trial compared renal function and viral efficacy in patients with suppressed viral load treated with RAL+DRV/r and ritonavir-boosted lopinavir (LPV/r) plus tenofovir/emtricitabine (TVD), who had been previously on LPV/r+TVD. The primary endpoint was the proportion of patients with >10% improvement in estimated glomerular filtration rate (eGFR) at 48 weeks calculated with Cockcroft-Gault equation.

Results

58 randomized and treatment-exposed patients were analyzed (28 on RAL+DRV/r and 30 on LPV/r+TVD). Greater than 10% improvement in eGFR was noted in 6 (25%) out of 24 with RAL+DRV/r and 3 (11%) of 28 with LPV/r+TVD, and the difference was not statistically significant (p=0.272, 95% CI -0.067 to 0.354). Sensitivity analyses using three other equations for eGFR showed the same results. Urinary β2 microglobulin, a sensitive marker of tenofovir tubulopathy, significantly improved with RAL+DRV/r than with LPV/r+TVD (-271 versus -64 µg/gCr, p=0.026). Per protocol analysis showed that the HIV-RNA was <50 copies/mL at week 48 in all patients of both arms (24 in RAL+DRV and 29 in LPV/r+TVD).

Conclusions

Switching LPV/r+TVD to RAL+DRV/r did not significantly increase the proportion of patients who showed >10% improvement in renal function among those with relatively preserved eGFR. However, the switch improved urinary β2 microglobulin, suggesting that discontinuation of TDF might be beneficial in the long-term. RAL+DRV/r showed favorable viral efficacy in patients with suppressed viral load.

Trial Registration

ClinicalTrials.gov NCT01294761 http://clinicaltrials.gov/ct2/show/NCT01294761?term=SPARE&rank=2, Umin Clinical Trials Registry UMIN000005116 http://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000006083&language=J)

The next therapeutic challenge in HIV: polypharmacy

With the adoption of combination antiretroviral therapy (ART), most HIV-infected individuals in care are on five or more medications and at risk of harm from polypharmacy, a risk that likely increases with number of medications, age, and physiologic frailty. Established harms of polypharmacy include decreased medication adherence and increased serious adverse drug events, including organ system injury, hospitalization, geriatric syndromes (falls, fractures, and cognitive decline) and mortality. The literature on polypharmacy among those with HIV infection is limited, and the literature on polypharmacy among non-HIV patients requires adaptation to the special issues facing those on chronic ART. First, those aging with HIV infection often initiate ART in their 3rd or 4th decade of life and are expected to remain on ART for the rest of their lives. Second, those with HIV may be at higher risk for age-associated comorbid disease, further increasing their risk of polypharmacy. Third, those with HIV may have an enhanced susceptibility to harm from polypharmacy due to decreased organ system reserve, chronic inflammation, and ongoing immune dysfunction. Finally, because ART is life-extending, nonadherence to ART is particularly concerning. After reviewing the relevant literature, we propose an adapted framework with which to address polypharmacy among those on lifelong ART and suggest areas for future work.

Randomized placebo-controlled study of the safety, tolerability, antiviral activity, and pharmacokinetics of 10-day monotherapy with BMS-986001, a novel HIV NRTI, in treatment-experienced HIV-1-infected subjects

OBJECTIVE

To investigate the safety, tolerability, pharmacokinetics, and antiviral activity of BMS-986001 (a nucleoside reverse transcriptase inhibitor) in treatment-experienced, HIV-1-infected subjects not exposed to antiretroviral treatment in the previous 3 months.

METHODS

Thirty-two HIV-1-infected subjects were randomized (3:1) to receive BMS-986001 or placebo once daily for 10 days in this double-blind, placebo-controlled, dose-escalating monotherapy phase IIa study. There were 4 treatment groups (100, 200, 300, and 600 mg, all once daily) of 8 subjects each (BMS-986001, n = 6/placebo n = 2).

RESULTS

BMS-986001 was generally well tolerated, with no discontinuations due to adverse events and no deaths occurring. Adverse events were experienced by 22 of 24 BMS-986001-treated subjects and did not seem to be dose related. The majority were mild and considered unrelated or unlikely to be related to the study drug. The pharmacokinetics of BMS-986001 were dose proportional. Median decrease in plasma HIV-1 RNA from baseline to day 11 was 0.97, 1.15, 1.28, and 1.15 log10 copies/mL for BMS-986001 at 100, 200, 300, and 600 mg, respectively. Plasma area under the curve correlated with the antiviral activity of BMS-986001, indicating that area under the curves produced by 100-600 mg doses were on the upper end of the exposure-response curve. One subject with a single thymidine analog mutation at baseline responded well to BMS-986001.

CONCLUSIONS

Administration of BMS-986001 for 10 days resulted in substantial decreases in plasma HIV-1 RNA levels for all dose groups and was generally well tolerated. These data support continued clinical development of BMS-986001 at a dose of 100 mg, once daily or greater.

TRIAL REGISTRATION

EUDRACT Number 2008-004810-29.

Update on tenofovir toxicity in the kidney

Tenofovir (TFV) is a widely used and effective treatment for HIV infection. Numerous studies have shown that TFV exposure is associated with small but significant declines in estimated glomerular filtration rate (eGFR). However, TFV toxicity is targeted mainly at the proximal tubule (PT), and in severe cases can cause the renal Fanconi syndrome or acute kidney injury. Severe toxicity occurs in a minority of patients, but milder PT dysfunction is more common; the long-term significance of this on kidney and bone health is uncertain. Recent work suggests that changes in eGFR on TFV therapy might be explained by inhibition of PT creatinine secretion rather than actual alterations in glomerular function. Risk factors for nephrotoxicity include pre-existing kidney disease, increased age, and low body mass. Mitochondria in the PT are the targets of TFV toxicity, but the exact mechanisms remain unclear. Substantial improvement of renal function occurs in many patients with TFV toxicity upon stopping therapy, but function does not always return to baseline. In recent years, TFV usage has been extended to new clinical spheres, including pediatrics, resource-poor settings and treatment of hepatitis B infection; theoretical reasons exist as to why some of these patients might be at higher or lower risk of TFV toxicity. Finally, strategies have been proposed to prevent TFV toxicity or enhance recovery.

Polypharmacy in the HIV-infected older adult population

The prevalence of human immunodeficiency virus (HIV) infection among people older than 50 years is increasing. Older HIV-infected patients are particularly at risk for polypharmacy because they often have multiple comorbidities that require pharmacotherapy. Overall, there is not much known with respect to both the impact of aging on medication use in HIV-infected individuals, and the potential for interactions with highly active antiretroviral therapy (HAART) and coadministered medications and its clinical consequences. In this review, we aim to provide an overview of polypharmacy with a focus on its impact on the HIV-infected older adult population and to also provide some clinical considerations in this high-risk population.

Evidence for risk stratification when monitoring for toxicities following initiation of combination antiretroviral therapy

OBJECTIVE

Laboratory monitoring is recommended during combination antiretroviral therapy (cART), but the pattern of detected abnormalities and optimal monitoring are unknown. We assessed laboratory abnormalities during initial cART in 2000-2010 across the United States.

DESIGN

Observational study in the Centers for AIDS Research Network of Integrated Clinical Systems Cohort.

METHODS

Among patients with normal results within a year prior to cART initiation, time to first significant abnormality was assessed by Kaplan-Meier curves stratified by event type, with censoring at first of regimen change, loss to follow-up, or 104 weeks. Incidence rates of first events were estimated using Poisson regression; multivariable analyses identified associated factors. Results were stratified by time (16 weeks) from therapy initiation.

RESULTS

A total of 3470 individuals contributed 3639 person-years. Median age, pre-cART CD4, and follow-up duration were 40 years, 206 cells/μl, and 51 weeks, respectively. Incidence rates for significant abnormalities (per 100 person-years) in the first 16 weeks post-cART initiation were as follows: lipid=49 [95% confidence interval (CI) 41-58]; hematologic=44 (40-49); hepatic=24 (20-27); and renal=9 (7-11), dropping substantially during weeks 17-104 of cART to lipid=23 (18-29); hematologic=5 (4-6); hepatic=6 (5-8); and renal=2 (1-3) (all P<0.05). Among patients receiving initial cART with no prior abnormality (N=1889), strongest associations for hepatic abnormalities after 16 weeks were hepatitis B and C [hazard ratio=2.3 (95% CI 1.2-4.5) and hazard ratio=3.0 (1.9-4.5), respectively]. The strongest association for renal abnormalities was hypertension [hazard ratio=2.8 (1.4-5.6)].

CONCLUSION

New abnormalities decreased after week 16 of cART. For abnormalities not present by week 16, subsequent monitoring should be guided by comorbidities.

Role of traditional risk factors and antiretroviral drugs in the incidence of chronic kidney disease, ANRS CO3 Aquitaine cohort, France, 2004-2012

Objective

To examine the role of antiretroviral drugs (ART), HIV-related and traditional risk factors on the incidence of chronic kidney disease (CKD) in HIV-infected patients.

Design

Prospective hospital-based cohort of HIV-infected patients from 2004 to 2012.

Methods

CKD was defined using MDRD equation as an estimated glomerular filtration rate (eGFR) less than 60 ml/mn/1.73 m² at 2 consecutive measurements ≥3 months apart. Poisson regression models were used to study determinants of CKD either measured at baseline or updated. ART exposure was classified as ever or never. We additionally tested the role of tenofovir (TDF), whether or not prescribed concomitantly with a Protease Inhibitor (PI), taking into account the cumulative exposure to the drug.

Results

4,350 patients (74% men) with baseline eGFR>60 ml/mn/1.73 m² were followed for a median of 5.8 years. At the end of follow-up, 96% had received ART, one third of them (35%) jointly received TDF and a PI. Average incidence rate of CKD was 0.95% person-years of follow-up. Incidence of CKD was higher among women (IRR = 2.2), older patients (>60 y vs <45 y: IRR = 2.5 and 45–60 y: IRR = 1.7), those with diabetes (IRR = 1.9), high blood pressure (IRR = 1.5), hyperlipidemia (IRR = 1.5), AIDS stage (IRR = 1.4), low baseline eGFR (IRR = 15.8 for 60<eGFR<70 ml/mn/1.73 m² vs >90 and IRR = 7.1 for 70<eGFR<80 ml/mn/1.73 m²), current CD4+<200 cells/mm³ vs >500/mm³ (IRR = 2.5), and exposure to TDF (IRR = 2.0). Exposure to TDF was even strongly associated with CKD when co-administered with PIs (IRR = 3.1 vs 1.3 when not, p<0,001). A higher risk of CKD was found when tenofovir exposure was >12 months [IRR = 3.0 with joint PIs vs 1.3 without (p<0.001)]. A vast majority of those developing CKD (76.6%) had a baseline eGFR between 60 and 80 ml/mn/1.73 m².

Conclusion

In patients with eGFR between 60 and 80 mL/min/1.73 m², a thorough control of CKD risk factors is warranted. The use of TDF, especially when co-administered with PIs, should be mentioned as a relative contraindication in presence of at least one of these risk factors.

Host APOL1 genotype is independently associated with proteinuria in HIV infection

Proteinuria is associated with adverse clinical outcomes in HIV infection. Here we evaluated whether APOL1 risk alleles, previously associated with advanced kidney disease, are independently associated with proteinuria in HIV infection in a cross-sectional study of HIV-infected women in the Women's Interagency HIV Study. We estimated the percent difference in urine protein excretion and odds of proteinuria (≥200 mg/g) associated with two versus one or no APOL1 risk allele using linear and logistic regression, respectively. Of 1285 women successfully genotyped, 379 carried one and 80 carried two risk alleles. Proteinuria was present in 124 women, 78 of whom had proteinuria confirmed on a second sample. In women without prior AIDS, two risk alleles were independently associated with a 69% higher urine protein excretion (95% confidence interval (CI): 36, 108) and five-fold higher odds of proteinuria (95% CI: 2.45, 10.37) as compared with one or no risk allele. No association was found in women with prior AIDS. Analyses in which women with impaired kidney function were excluded and proteinuria was confirmed by a second urine sample yielded similar estimates. Thus, APOL1 risk alleles are associated with significant proteinuria in HIV-infected persons without prior clinical AIDS, independent of clinical factors traditionally associated with proteinuria. Trials are needed to determine whether APOL1 genotyping identifies individuals who could benefit from earlier intervention to prevent overt renal disease.

Tubular and glomerular proteinuria in HIV-infected adults with estimated glomerular filtration rate ≥ 60 ml/min per 1.73 m2

OBJECTIVE

To assess the frequency of glomerular and tubular proteinuria in a cohort of HIV-infected patients, and to determine the factors associated with each type of injury.

DESIGN

Cross-sectional study of 1210 consecutive HIV-infected adults followed in HIV outpatient unit (Montpellier/France).

METHODS

Spot urine protein to creatinine (uPCR), albumin to creatinine (uACR) and albumin to protein (uAPR) ratios were assessed. Glomerular injury was defined as uACR at least 30 mg/g or uPCR at least 200 mg/g with uAPR at least 0.4. Tubular injury was defined as uPCR 200 mg/g or more with uAPR less than 0.4. Multivariate logistic regression identified independent factors of each type of proteinuria, in the 1158 patients with estimated glomerular filtration rate (eGFR) at least 60 ml/min per 1.73 m, using re-expressed modification of diet in renal disease equation.

RESULTS

Frequency of proteinuria was 18.2% among patients with eGFR at least 60 ml/min per 1.73 m consisting in tubular proteinuria for 50.7% of them. Factors associated with glomerular proteinuria were age [OR 1.34/10-year increment (95%CI: 1.08-1.66)], diabetes [OR 3.37 (95%CI: 1.53-7.44)], and arterial hypertension [OR 2.52 (95%CI: 1.36-4.66)]. Factors associated with tubular proteinuria were age [OR 1.43 (95%CI: 1.14-1.79)], current tenofovir use [OR 3.52 (95%CI: 1.86-6.65)], hepatitis C co-infection [OR 1.62 (95%CI: 1.00-2.65)], AIDS stage [OR 1.83 (95%CI: 1.18-2.82)], CD4 cell count less than 200 per μl [OR 2.48 (95%CI: 1.31-4.70)].

CONCLUSION

This study distinguished risk factors for tubular injury, mainly related to HIV disease and its treatment (tenofovir), and glomerular injury, linked to non HIV-related variables (age, diabetes, hypertension). Measuring uPCR, uACR and uAPR may help with the detection and specific management of early chronic kidney disease in HIV-infected patients having normal or sub-normal eGFR.