Greater decrease in bone mineral density with protease inhibitor regimens compared with nonnucleoside reverse transcriptase inhibitor regimens in HIV-1 infected naive patients

Effects of vitamin D deficiency and combination antiretroviral therapy on bone in HIV-positive patients

OBJECTIVES

In the era of combination antiretroviral therapy (cART), vitamin D deficiency, low bone mineral density (BMD) and fractures have emerged as subjects of concern in HIV-positive patients. Testing for vitamin D deficiency has been widely adopted in clinical practice even though the benefits of vitamin D supplementation in this population remain uncertain. The objective of this review was to evaluate the evidence for such a strategy.

DESIGN

Systematic review of the literature on vitamin D deficiency in HIV infection, the effects of cART on vitamin D status, and the effects of vitamin D deficiency and cART on parathyroid hormone (PTH), bone turnover, BMD and the incidence of fractures in HIV-positive patients.

METHODS

PubMed was used to identify relevant articles up to September 2011.

RESULTS

Vitamin D deficiency, secondary hyperparathyroidism and low BMD are common in HIV-positive patients. Efavirenz is associated with a reduction in 25-hydroxy vitamin D levels, tenofovir with secondary hyperparathyroidism, and cART with increased bone turnover and low BMD. The clinical significance of low BMD, however, remains unclear, especially in younger patients. Although the incidence of fractures may be increased in HIV-positive patients, the contribution of low BMD and vitamin D deficiency to these fractures is uncertain. Limited data on vitamin D supplementation in HIV-positive patients have shown transient, beneficial effects on PTH, but no effects on BMD.

CONCLUSION

The benefits of vitamin D supplementation in this population need to be demonstrated before widespread 'test and treat' policies can be recommended as part of routine clinical practice.

Incidence of low and high-energy fractures in persons with and without HIV infection: a Danish population-based cohort study

OBJECTIVE

To compare fracture risk in persons with and without HIV infection and to examine the influence of highly active antiretroviral therapy (HAART) initiation on risk of fracture.

DESIGN

Population-based nationwide cohort study using Danish registries.

METHODS

Outcome measures were time to first fracture at any site, time to first low-energy and high-energy fracture in HIV-infected patients (n = 5306) compared with a general population control cohort (n = 26 530) matched by sex and age during the study period 1995-2009. Cox regression analyses were used to estimate incidence rate ratios (IRRs).

RESULTS

HIV-infected patients had increased risk of fracture [IRR 1.5, 95% confidence interval (CI) 1.4-1.7] compared with population controls. The relative risk was lower in HIV-monoinfected patients (IRR 1.3, 95% CI 1.2-1.4) than in HIV/hepatitis C virus (HCV)-coinfected patients (IRR 2.9, 95% CI 2.5-3.4).Both HIV-monoinfected and HIV/HCV-coinfected patients had increased risk of low-energy fracture, IRR of 1.6 (95% CI 1.4-1.8) and 3.8 (95% CI 3.0-4.9). However, only HIV/HCV-coinfected patients had increased risk of high-energy fracture, IRR of 2.4 (95% CI 2.0-2.9). Among HIV-monoinfected patients the risk of low-energy fracture was only significantly increased after HAART exposure, IRR of 1.8 (95% CI 1.5-2.1). The increased risk in HAART-exposed patients was not associated with CD4 cell count, prior AIDS, tenofovir or efavirenz exposure, but with comorbidity and smoking.

CONCLUSION

HIV-infected patients had increased risk of fracture compared with population controls. Among HIV-monoinfected patients the increased risk was observed for low-energy but not for high-energy fractures, and the increased risk of low-energy fracture was only observed in HAART-exposed patients.

Noncanonical Wnt signaling promotes osteoclast differentiation and is facilitated by the human immunodeficiency virus protease inhibitor ritonavir

Wnt proteins that signal via the canonical Wnt/β-catenin pathway directly regulate osteoblast differentiation. In contrast, most studies of Wnt-related effects on osteoclasts involve indirect changes. While investigating bone mineral density loss in the setting of human immunodeficiency virus (HIV) infection and its treatment with the protease inhibitor ritonavir (RTV), we observed that RTV decreased nuclear localization of β-catenin, critical to canonical Wnt signaling, in primary human and murine osteoclast precursors. This occurred in parallel with upregulation of Wnt5a and Wnt5b transcripts. These Wnts typically stimulate noncanonical Wnt signaling, and this can antagonize the canonical Wnt pathway in many cell types, dependent upon Wnt receptor usage. We now document RTV-mediated upregulation of Wnt5a/b protein in osteoclast precursors. Recombinant Wnt5b and retrovirus-mediated expression of Wnt5a enhanced osteoclast differentiation from human and murine monocytic precursors, processes facilitated by RTV. In contrast, canonical Wnt signaling mediated by Wnt3a suppressed osteoclastogenesis. Both RTV and Wnt5b inhibited canonical, β-catenin/T cell factor-based Wnt reporter activation in osteoclast precursors. RTV- and Wnt5-induced osteoclast differentiation were dependent upon the receptor-like tyrosine kinase Ryk, suggesting that Ryk may act as a Wnt5a/b receptor in this context. This is the first demonstration of a direct role for Wnt signaling pathways and Ryk in regulation of osteoclast differentiation, and its modulation by a clinically important drug, ritonavir. These studies also reveal a potential role for noncanonical Wnt5a/b signaling in acceleration of bone mineral density loss in HIV-infected individuals, and illuminate a potential means of influencing such processes in disease states that involve enhanced osteoclast activity.

Prospective evaluation of bone mineral density among middle-aged HIV-infected and uninfected women: Association between methadone use and bone loss

OBJECTIVE

We undertook a prospective study to assess the impact of HIV infection on BMD in a cohort of HIV-infected and uninfected women that included illicit drug users, and to measure the contribution of traditional risk factors as well as HIV-related factors to loss of BMD over time.

METHODS

We analyzed BMD at baseline and after ≥18 months in 245 middle-aged HIV-infected and 219 uninfected women, and conducted linear regression analysis to determine factors associated with annual BMD change at the femoral neck, total hip and lumbar spine.

RESULTS

HIV-infected women had lower baseline BMD at the femoral neck and total hip compared with controls; unadjusted rates of BMD change did not differ by HIV status at any site. In multivariable analyses, we found that HIV seropositivity without protease inhibitor (PI) use was associated with BMD decline at the lumbar spine (-.009g/cm(2) per year, p=.03). Additional factors associated with BMD decline were: postmenopausal status, lower BMI, and methadone use at the lumbar spine; postmenopausal status and hepatitis C seropositivity at the femoral neck; and postmenopausal status, age, smoking, and lower BMI at the total hip (all p<.05). Among HIV-infected women, ≥3 years of PI use was associated with an increase in lumbar spine BMD (.013g/cm(2) per year, p=.008).

CONCLUSIONS

Bone loss among HIV-infected middle-aged women was modest, and possibly mitigated by PI use. Methadone use was associated with BMD decline, and should be considered when evaluating women for osteoporosis risk.

Osteoporosis and Vitamin D Deficiency in HIV-Positive Patients

Objective:

To review the epidemiology and pathophysiology of osteoporosis in patients with HIV infection and discuss vitamin D deficiency and the treatment of HIV-positive patients with osteoporosis.

Data Sources:

A search of PubMed (1980–June 2011) was conducted using the terms osteoporosis, HIV, vitamin D deficiency, and treatment.

Study Selection and Data Extraction:

Epidemiologic studies, clinical trials, and meta-analyses published in English were included. A manual review of the bibliographies of available literature was conducted and relevant articles were reviewed for inclusion.

Data Synthesis:

Patients with HIV infection are living longer with the use of potent antiretroviral therapy (ART) and are at increased risk for osteoporosis. Several studies have shown that HIV infection can affect bone health and increase the risk for osteoporosis. In addition, ART, and tenofovir in particular, may affect bone turnover. Studies and meta-analyses have shown an increased prevalence of osteopenia and osteoporosis in HIV-positive patients compared to noninfected controls. Recent reports also show increased prevalence of fractures and low vitamin D concentrations in HIV-positive patients. Osteoporosis treatments used in patients with HIV infection are similar to treatments for noninfected patients. HIV-positive patients should be monitored and treated to prevent the progression and complications of osteoporosis.

Conclusions:

HIV-positive patients are at increased risk for osteoporosis and vitamin D deficiency due to disease and treatment influences on bone health. These patients should be identified and treated to prevent the morbidity and mortality associated with osteoporosis.

Controlled HIV viral replication, not liver disease severity associated with low bone mineral density in HIV/HCV co-infection

BACKGROUND & AIMS

To evaluate the prevalence and risk factors for low bone mineral density (BMD) in persons co-infected with HIV and Hepatitis C.

METHODS

HIV/HCV co-infected study participants (n=179) were recruited into a prospective cohort and underwent dual-energy X-ray absorptiometry (DXA) within 1 year of a liver biopsy. Fibrosis staging was evaluated according to the METAVIR system. Osteoporosis was defined as a T-score ≤-2.5. Z-scores at the total hip, femoral neck, and lumbar spine were used as the primary outcome variables to assess the association between degree of liver disease, HIV-related variables, and BMD.

RESULTS

The population was 65% male, 85% Black with mean age 50.3 years. The prevalence of osteoporosis either at the total hip, femoral neck, or lumbar spine was 28%, with 5% having osteoporosis of the total hip, 6% at the femoral neck, 25% at the spine. The mean Z-scores (standard deviation) were -0.42 (1.01) at the total hip, -0.16 (1.05) at the femoral neck, and -0.82 (1.55) at the lumbar spine. In multivariable models, controlled HIV replication (HIV RNA <400 copies/ml vs. ≥400 copies/ml) was associated with lower Z-scores (mean ± standard error) at the total hip (-0.44 ± 0.17, p = 0.01), femoral neck (-0.59 ± 0.18, p = 0.001), and the spine (-0.98 ± 0.27, p = 0.0005). There was no association between degree of liver fibrosis and Z-score.

CONCLUSIONS

Osteoporosis was very common in this population of predominately African-American HIV/HCV co-infected patients, particularly at the spine. Lower BMD was associated with controlled HIV replication, but not liver disease severity.

Low bone mass prevalence, therapy type, and clinical risk factors in an HIV-infected Brazilian population

Low bone mineral density (BMD) has been described in human immunodeficiency virus (HIV)-infected patients, but data on associated factors are still unclear, and to our knowledge, no reports are available in Brazil. Our goal was to evaluate BMD in HIV patients attending an outpatient clinic in Vitoria, Brazil. A sectional study was performed in 300 HIV-infected patients to measure BMD by dual-energy X-ray absorptiometry (DXA). Age, gender, anthropometric parameters, nadir and current CD4 cell count, HIV viral load, smoking habit, and current antiretroviral therapy (ART) associations were investigated by multivariable analysis. Based on World Health Organization T-score ranges, low BMD (T-score <-1.0 standard deviation [SD] in postmenopausal women and men aged 50 and older or Z-score <- 2.0 SD in premenopausal women and men below the age of 50) was detected in 54.7% (95% confidence interval: 49.1-60.3%) of the 300 enrolled patients. The observed median age was 46 yr (interquartile range: 39-52), 58% were male, 88.5% were on ART, and 21.4% smoked. The following factors were identified, by multiple logistic modeling, as being independently associated with low BMD: (1) male gender (4.6 [1.28-16.39]), (2) body mass index lower than 25 kg/m(2) (2.9 [1.31-6.49]), (3) menopause (13.4 [2.53-71.12]), and (4) HIV-1 undetectable viral load (7.9 [1.96-32.25]). Conversely, zidovudine (0.2 [0.04-0.85]) and nevirapine (0.1 [0.02-0.38]) use were inversely associated with low BMD. Low BMD was frequently found in our cohort of about 300 Brazilian HIV-infected subjects. This study supports the need for periodic DXA testing in HIV outpatient clinics.

Bone mineral density and fractures in antiretroviral-naive persons randomized to receive abacavir-lamivudine or tenofovir disoproxil fumarate-emtricitabine along with efavirenz or atazanavir-ritonavir: Aids Clinical Trials Group A5224s, a substudy of ACTG A5202

BACKGROUND

Long-term effects of abacavir (ABC)-lamivudine (3TC), compared with tenofovir (TDF)-emtricitabine (FTC) with efavirenz (EFV) or atazanavir plus ritonavir (ATV/r), on bone mineral density (BMD) have not been analyzed.

METHODS

A5224s was a substudy of A5202, in which HIV-infected treatment-naive participants were randomized and blinded to receive ABC-3TC or TDF-FTC with open-label EFV or ATV/r. Primary bone end points included Dual-emission X-ray absorbtiometry (DXA)-measured percent changes in spine and hip BMD at week 96. Primary analyses were intent-to-treat. Statistical tests used the factorial design and included linear regression, 2-sample t, log-rank, and Fisher's exact tests.

RESULTS

Two hundred sixty-nine persons randomized to 4 arms of ABC-3TC or TDF-FTC with EFV or ATV/r. At baseline, 85% were male, and 47% were white non-Hispanic; the median HIV-1 RNA load was 4.6 log(10) copies/mL, the median age was 38 years, the median weight was 76 kg, and the median CD4 cell count was 233 cells/μL. At week 96, the mean percentage changes from baseline in spine and hip BMD for ABC-3TC versus TDF-FTC were -1.3% and -3.3% (P = .004) and -2.6% and -4.0% (P = .024), respectively; and for EFV versus ATV/r were -1.7% and -3.1% (P = .035) and -3.1% and -3.4% (P = .61), respectively. Bone fracture was observed in 5.6% of participants. The probability of bone fractures and time to first fracture were not different across components.

CONCLUSIONS

Compared with ABC-3TC, TDF-FTC-treated participants had significantly greater decreases in spine and hip BMD, whereas ATV/r led to more significant losses in spine, but not hip, BMD than EFV. Clinical Trials Registration. NCT00118898.

The Rapidly Evolving Research on Vitamin D Among HIV-Infected Populations

With ongoing improvement in antiretroviral therapy, mortality among HIV-infected persons has dramatically decreased. For HIV-infected persons who remain engaged in care on suppressive therapy, life expectancy approaches that of the general population. Additionally, we have seen increases in comorbidities traditionally associated with aging: diabetes, hypertension, dyslipidemia, ischemic heart disease, and osteoporosis. Vitamin D deficiency has also been identified as a highly prevalent entity among HIV-infected populations. The association of vitamin D deficiency with several of these comorbidities and its impact on immune function provide the impetus for well-designed studies to evaluate the impact of vitamin D supplementation on HIV disease and antiretroviral therapy. This review summarizes the role of vitamin D in several disease states that are prevalent among HIV populations, with a specific focus on bone health and the interactions with antiretroviral medications.

Prevention of bone loss and management of fracture risk in HIV-infected individuals: case studies and recommendations for different patient subgroups

Increased life-expectancy and the need for long-term antiretroviral therapy have brought new challenges to the clinical management of HIV-infected individuals. While the prevalence of osteoporosis and fractures is probably increased in HIV-infected patients, optimal strategies for risk assessment and treatment in this relatively young population are yet to be defined. Prevention of bone loss is likely to become an important component of HIV care as the HIV-infected patient population grows older. In this article, we present an overview of the literature on bone loss in individuals with HIV and discuss the practical application of the European AIDS Clinical Society (EACS) guidelines to a range of clinical case scenarios.

Endocrine complications of human immunodeficiency virus infection: hypogonadism, bone disease and tenofovir-related toxicity

Treatment with highly active antiretroviral therapy (HAART) has revolutionized care of patients with HIV infection. The cost of increased survival has been antiretroviral toxicity and increasing age-related co-morbidities that include significant metabolic issues. Hypogonadism was first described in the setting of advanced AIDS and can be primary or secondary. Data regarding treatment largely concern patients with wasting. Varied syndromes involving bone have been described in patients with HIV including osteonecrosis, low bone mineral density (BMD) and osteoporosis, and rarely osteomalacia. Low BMD leading to osteoporosis is the most common bone pathology and may be as a result of HIV infection, drug toxicity or co-morbidities. However, increasingly fragility fractures are reported in HIV-infected patients, suggesting bone demineralization in this population is of clinical relevance. Further research is required to understand its pathogenesis and determine effective management; however, initiation of antiretroviral therapy seems to accelerate (in the short-term) bone demineralization. One particular antiretroviral agent, tenofovir is widely used and is potentially implicated as having a greater role in long-term bone and renal dysfunction. As this population ages, screening for low BMD will become increasingly more important.

Bone mineral density in HIV-infected women taking antiretroviral therapy: a systematic review

There is a high prevalence of osteoporosis in HIV-infected patients. Initially described in HIV-positive men, studies have also demonstrated a high prevalence of osteoporosis in HIV-infected women. It would appear that antiretroviral therapy (ART) plays an important role in the pathogenesis of osteoporosis in HIV-infected patients, although little is known about its importance in relation to osteoporosis and fractures in HIV-positive women. The aim of this systematic review was to evaluate the frequency of bone loss, bone mineral density (BMD) and fractures in HIV-positive women taking ART or protease inhibitors (PI). After screening 597 citations from the databases of PubMed, EMBASE and Lilacs, five studies were selected for the review. A difference was demonstrated of over 3% in the BMD at the femoral neck of HIV-positive women taking PI/ART. No difference was registered in the BMD at the lumbar spine between users and non-users of PI/ART. The lack of studies has made it impossible to reach any conclusion regarding the occurrence of fractures.

Effects of HIV infection and antiretroviral therapy with ritonavir on induction of osteoclast-like cells in postmenopausal women

SUMMARY

Ritonavir (RTV) is a commonly used antiretroviral associated with bone loss. We show that peripheral blood mononuclear cells (PBMCs) from human immunodeficiency virus (HIV)-positive women on RTV are more likely to differentiate into osteoclast-like cells when cultured with their own sera than PBMCs and sera from HIV- women or HIV+ on other antiretrovirals.

INTRODUCTION

RTV increases differentiation of human adherent PBMCs to functional osteoclasts in vitro, and antiretroviral regimens containing RTV have been associated with low bone mineral density (BMD) and bone loss.

METHODS

BMD, proresorptive cytokines, bone turnover markers (BTMs), and induction of osteoclast-like cells from adherent PBMCs incubated either with macrophage colony-stimulating factor (MCSF) and receptor activator of nuclear factor κB ligand (RANKL) or with autologous serum were compared in 51 HIV- and 68 HIV+ postmenopausal women.

RESULTS

BMD was lower, and serum proresorptive cytokines and BTMs were higher in HIV+ versus HIV- women. Differentiation of osteoclast-like cells from adherent PBMCs exposed to either MCSF/RANKL or autologous serum was greater in HIV+ women. Induction of osteoclast-like cells was greater from PBMCs exposed to autologous sera from HIV+ women on RTV-containing versus other regimens (172 ± 14% versus 110 ± 10%, p < 0.001). Serum-based induction of osteoclast-like cells from adherent PBMCs correlated with certain BTMs but not BMD.

CONCLUSIONS

HIV infection and antiretroviral therapy are associated with higher BTMs and increased differentiation of osteoclast-like cells from adherent PBMCs, especially in women on regimens containing RTV. HIV+ postmenopausal women receiving RTV may be at greater risk for bone loss.

Prospective one-year bone loss in treatment-naïve HIV+ men and women on single or multiple drug HIV therapies

Antiretroviral therapy has decreased the rate of HIV-related mortality and extended the life span of HIV patients. Current guidelines recommend the use of a 3-drug regimen, such as two nucleoside reverse transcriptase inhibitors and a protease inhibitor, boosted by ritonavir. Osteoporosis can be associated with the HIV disease itself or with antiretroviral therapy. Many trials have been conducted employing a single drug regimen to simplify antiretroviral therapy but few studies assessed the effect of the single drug regimen on bone mineral density (BMD). The objectives of the study were to assess and compare the relative (%) changes in lumbar spine and hip BMD over 48 weeks in HIV patients treated with mono or triple antiretroviral regimens The study was conducted using data from a randomized trial (MONARK) conducted in 136 antiretroviral-naïve HIV patients (89 men and 47 women) comparing the antiviral efficacy of a single-drug protease inhibitor regimen of lopinavir/ritonavir (LPV/r) versus LPV/r in combination with zidovudine (ZDV) and lamivudine (3TC). Lumbar spine and total hip BMD were assessed in 100 patients by dual-energy X-ray absorptiometry at baseline and 48 weeks. 48 week-BMD data were available for 43 patients (mean age 37years) with a mean baseline lumbar spine Z-score of -0.1 in the LPV/r monotherapy group and for 25 patients (mean age 35.8years) with a mean baseline lumbar spine Z-score of -0.2 in the LPV/r+ZDV+3TC group. After 48weeks, lumbar spine BMD significantly decreased by 4.4% (-5.1% to -2.1%, P≤0.001) in the LPV/r group and by 4.0% (-5.0% to -1.7%, P≤0.0001) in the LPV/r+ZDV+3TC group. There was no significant difference in BMD changes between the two groups. These results suggest that bone loss is observed 48 weeks after the initiation of antiretroviral therapy, whether the patients receive a single- or triple-drug antiretroviral regimen.

Markers of bone turnover are elevated in patients with antiretroviral treatment independent of the substance used

OBJECTIVES

Osteoporosis and bone fractures are correlated to antiretroviral treatment. It is not clear whether some substances comprise greater risks of bone loss than others.

METHODS

We measured pyridinoline, deoxypyridinoline crosslinks, and bone-specific alkaline phosphatase in 113 HIV-positive patients. We compared patients with and without antiretroviral treatment. We then compared patients with versus without tenofovir and patients with protease inhibitor versus nonnucleoside reverse transcriptase inhibitor use.

RESULTS

Bone-specific alkaline phosphatase, pyridinoline, and deoxypyridinoline crosslinks were significantly higher in patients with antiretroviral treatment compared with patients without antiretroviral treatment: 24.5 versus 13.04 pg/L (P < 0.001), 82.73 versus 51.93 nmol/mmol (P < 0.001), and 16.56 versus 9.94 nmol/mmol (P < 0.001), respectively. In contrast, no difference was found between patients with and without tenofovir: 25.38 versus 20.02 pg/l (P = 0.1); 79.85 versus 83.95 nmol/mmol (P = 0.64), and 19.12 versus 14.00 nmol/mmol (P = 0.14), respectively. Comparison between patients with protease inhibitor versus nonnucleoside reverse transcriptase inhibitor yielded no difference either: 23.07 versus 27.18 pg/L (P = 0.24), 92.96 versus 80.73 nmol/mmol (P = 0.36), and 18.22 versus 16.39 nmol/mmol (P = 0.55).

CONCLUSION

Markers for bone turnover are higher in treated compared with untreated patients. No difference concerning tenofovir use or protease inhibitor versus nonnucleoside reverse transcriptase inhibitor use could be found.

Increased risk of fragility fractures among HIV infected compared to uninfected male veterans

Background

HIV infection has been associated with an increased risk of fragility fracture. We explored whether or not this increased risk persisted in HIV infected and uninfected men when controlling for traditional fragility fracture risk factors.

Methodology/Principal Findings

Cox regression models were used to assess the association of HIV infection with the risk for incident hip, vertebral, or upper arm fracture in male Veterans enrolled in the Veterans Aging Cohort Study Virtual Cohort (VACS-VC). We calculated adjusted hazard ratios comparing HIV status and controlling for demographics and other established risk factors. The sample consisted of 119,318 men, 33% of whom were HIV infected (34% aged 50 years or older at baseline, and 55% black or Hispanic). Median body mass index (BMI) was lower in HIV infected compared with uninfected men (25 vs. 28 kg/m²; p<0.0001). Unadjusted risk for fracture was higher among HIV infected compared with uninfected men [HR: 1.32 (95% CI: 1.20, 1.47)]. After adjusting for demographics, comorbid disease, smoking and alcohol abuse, HIV infection remained associated with an increased fracture risk [HR: 1.24 (95% CI: 1.11, 1.39)]. However, adjusting for BMI attenuated this association [HR: 1.10 (95% CI: 0.97, 1.25)]. The only HIV-specific factor associated with fragility fracture was current protease inhibitor use [HR: 1.41 (95% CI: 1.16, 1.70)].

Conclusions/Significance

HIV infection is associated with fragility fracture risk. This risk is attenuated by BMI.

HIV infection and bone disease: implications for an aging population

Now more than ever, the management of age-related problems, from cardiovascular morbidity to bone pathology, is increasingly relevant for HIV physicians. Low bone mineral density (BMD) and fractures are more common in HIV-infected patients. Although a multifactorial aetiology underlies this condition, increasing evidence suggests a role for antiretroviral therapy in low BMD, especially upon initiation. This review will detail the epidemiology, pathogenesis, diagnosis and management of osteoporosis and low BMD in HIV-infected patients, with particular emphasis on aging.

HIV-1 infection and antiretroviral therapies: risk factors for osteoporosis and bone fracture

PURPOSE OF REVIEW

Patients with HIV-1 infection/AIDS are living longer due to the success of highly active antiretroviral therapy (HAART). However, serious metabolic complications including bone loss and fractures are becoming common. Understanding the root causes of bone loss and its potential implications for aging AIDS patients will be critical to the design of effective interventions to stem a tidal wave of fractures in a population chronically exposed to HAART.

RECENT FINDINGS

Paradoxically, bone loss may occur not only due to HIV/AIDS but also as a consequence of HAART. The cause and mechanisms driving these distinct forms of bone loss, however, are complex and controversial. This review examines our current understanding of the underlying causes of HIV-1 and HAART-associated bone loss, and recent findings pertaining to the relevance of the immuno-skeletal interface in this process.

SUMMARY

It is projected that by 2015 more than half of the HIV/AIDS population in the USA will be over the age of 50 and the synergy between HIV and/or HAART-related bone loss with age-associated bone loss could lead to a significant health threat. Aggressive antiresorptive therapy may be warranted in high-risk patients.

HIV and bone loss

The use of antiretroviral therapy has significantly reduced the number of deaths due to HIV/AIDS. However, no current therapy can suppress the virus completely, and as the HIV-infected population continues to live longer new complications are emerging from the persistence of the virus and use of antiretroviral therapy. This review summarizes the clinical evidence linking HIV-associated osteoporosis to direct infection and antiretroviral therapy (ART) use. The purported molecular mechanisms involved in bone loss are also reviewed. Additionally, recommendations regarding the pharmacologic management of HIV/ART-related osteoporosis are given.

High prevalence of and progression to low bone mineral density in HIV-infected patients: a longitudinal cohort study

BACKGROUND

Low bone mineral density (BMD) is an emerging metabolic condition in HIV-infected patients; however, data on progression of this disease are scarce.

METHODS

We studied 671 patients with at least one dual-energy X-ray absorptiometry scan (391 of them ≥2 scans) to determine the prevalence and progression of BMD and establish related factors. Linear regression and logistic polytomic regression were used for the cross-sectional study and mixed effects and generalized estimating equations were used for the longitudinal study.

RESULTS

Osteopenia and osteoporosis were diagnosed in 47.5 and 23%, respectively. Progression to bone demineralization was observed in 28% of the patients over a median of 2.5 years (12.5% progressed to osteopenia and 15.6% to osteoporosis). In the 105 patients with at least 5 years of follow-up, progression was 47% (18% to osteopenia; 29% to osteoporosis). Factors associated with bone loss and progression were age [odds ratio (OR) 1.07; 95% confidence interval (CI) 1.05-1.08; P < 0.0001], male sex (OR 2.23; 95% CI 1.77-2.8; P < 0.0001), low body mass index (OR 1.14; 95% CI 1.11-1.17; P < 0.0001), time on protease inhibitor (OR 1.18; 95% CI 1.12-1.24; P < 0.0001), time on tenofovir (OR 1.08; 95% CI 1.03-1.14; P < 0.0019), and current use of protease inhibitors (OR 1.64; 95% CI 1.35-2.04; P < 0.0001).

CONCLUSIONS

Our results show a high prevalence of and considerable progression to osteopenia/osteoporosis in our cohort. Our findings support the importance of applying adequate strategies to prevent bone demineralization and of close monitoring of BMD in HIV-infected patients, specifically in at-risk patients who are taking antiretrovirals that affect bone mineralization.

Decrease of vitamin D concentration in patients with HIV infection on a non nucleoside reverse transcriptase inhibitor-containing regimen

Background

Vitamin D is an important determinant of bone health and also plays a major role in the regulation of the immune system. Interestingly, vitamin D status before the start of highly active antiretroviral therapy (HAART) has been recently associated with HIV disease progression and overall mortality in HIV-positive pregnant women. We prospectively studied vitamin D status in HIV individuals on HAART in Belgium.

We selected samples from HIV-positive adults starting HAART with a pre-HAART CD4 T-cell count >100 cells/mm³ followed up for at least 12 months without a treatment change. We compared 25-hydroxyvitamin D plasma [25-(OH)D] concentration in paired samples before and after 12 months of HAART. 25-(OH)D levels are presented using two different cut-offs: <20 ng/ml and <30 ng/ml.

Results

Vitamin D deficiency was common before HAART, the frequency of plasma 25-(OH)D concentrations below 20 ng/ml and 30 below ng/ml was 43.7% and 70.1% respectively. After 12 months on HAART, the frequency increased to 47.1% and 81.6%.

HAART for 12 months was associated with a significant decrease of plasma 25-(OH)D concentration (p = 0.001). Decreasing plasma 25-(OH)D concentration on HAART was associated in the multivariate model with NNRTI-based regimen (p = 0.001) and lower body weight (p = 0.008). Plasma 25-(OH)D concentrations decreased significantly in both nevirapine and efavirenz-containing regimens but not in PI-treated patients.

Conclusions

Vitamin D deficiency is frequent in HIV-positive individuals and NNRTI therapy further decreases 25-(OH)D concentrations. Consequently, vitamin D status need to be checked regularly in all HIV-infected patients and vitamin D supplementation should be given when needed.

Fracture incidence in HIV-infected women: results from the Women's Interagency HIV Study

BACKGROUND

The clinical importance of the association of HIV infection and antiretroviral therapy (ART) with low bone mineral density (BMD) in premenopausal women is uncertain because BMD stabilizes on established ART and fracture data are limited.

METHODS

We measured time to first new fracture at any site with median follow-up of 5.4 years in 2391 (1728 HIV-infected, 663 HIV-uninfected) participants in the Women's Interagency HIV Study (WIHS). Self-report of fracture was recorded at semiannual visits. Proportional hazard models assessed predictors of incident fracture.

RESULTS

At baseline, HIV-infected women were older (40 ± 9 vs. 36 ± 10 years, P < 0.0001), more likely to report postmenopausal status and be hepatitis C virus-infected, and weighed less than HIV-uninfected women. Among HIV-infected women, mean CD4(+) cell count was 482 cells/μl; 66% were taking ART. Unadjusted incidence of fracture did not differ between HIV-infected and uninfected women (1.8 vs. 1.4/100 person-years, respectively, P = 0.18). In multivariate models, white (vs. African-American) race, hepatitis C virus infection, and higher serum creatinine, but not HIV serostatus, were statistically significant predictors of incident fracture. Among HIV-infected women, older age, white race, current cigarette use, and history of AIDS-defining illness were associated with incidence of new fracture.

CONCLUSION

Among predominantly premenopausal women, there was little difference in fracture incidence rates by HIV status, rather traditional risk factors were important predictors. Further research is necessary to characterize fracture risk in HIV-infected women during and after the menopausal transition.

Bone disease in HIV infection: a practical review and recommendations for HIV care providers

Low bone mineral density (BMD) is prevalent in human immunodeficiency virus (HIV)-infected subjects. Initiation of antiretroviral therapy is associated with a 2%-6% decrease in BMD over the first 2 years, a decrease that is similar in magnitude to that sustained during the first 2 years of menopause. Recent studies have also described increased fracture rates in the HIV-infected population. The causes of low BMD in individuals with HIV infection appear to be multifactorial and likely represent a complex interaction between HIV infection, traditional osteoporosis risk factors, and antiretroviral-related factors. In this review, we make the point that HIV infection should be considered as a risk factor for bone disease. We recommend screening patients with fragility fractures, all HIV-infected post-menopausal women, and all HIV-infected men ⩾50 years of age. We also discuss the importance of considering secondary causes of osteoporosis. Finally, we discuss treatment of the more severe cases of bone disease, while outlining the caveats and gaps in our knowledge.

Prevalence of bone mineral density abnormalities and related risk factors in an ambulatory HIV clinic population

Bone mineral density (BMD) abnormalities are observed frequently among human immunodeficiency virus (HIV)-infected patients. Risk factors for reduced BMD in the setting of HIV have been previously studied, but detailed antiretroviral treatment history is often not available. A cross-sectional observational study was conducted between 2005 and 2007 among unselected HIV-infected adults attending an ambulatory urban HIV clinic. Dual-energy X-ray absorptiometry (DXA) scans of lumbar spine and femoral neck, full laboratory profile, detailed questionnaire, and antiretroviral history were obtained. Univariate and multivariate logistic regression analyses were performed to investigate factors associated with BMD below the expected range for age. Two hundred ninety patients completed the study: 80% Caucasians, 89% males, with median age of 49 yr. Low BMD as assessed by Z-score was present in 19.7% of the patients. By multivariate analysis, only lower body mass index (BMI) was an independent risk factor for low BMD. Cumulative exposure to protease inhibitors, non-nucleosides, and individual nucleoside and nucleotide analogs were not independently associated with low BMD. In conclusion, a 19.7% prevalence of abnormal BMD by DXA scan was identified in an unselected group of HIV-infected adults. Lower BMI was independently associated with low BMD. No correlation was found between abnormal BMD and cumulative exposure to any antiretroviral agents.

Bone mineral density changes in protease inhibitor-sparing vs. nucleoside reverse transcriptase inhibitor-sparing highly active antiretroviral therapy: data from a randomized trial

OBJECTIVE

The aim of the study was to compare changes in bone mineral density (BMD) over 144 weeks in HIV-infected patients initiating nucleoside reverse transcriptase inhibitor (NRTI)-sparing or protease inhibitor-sparing highly active antiretroviral therapy (HAART).

METHODS

Sixty-three HAART-naïve patients were randomized to zidovudine/lamivudine+efavirenz or lopinavir/ritonavir+efavirenz. We performed dual energy X-ray absorptiometry (DEXA) at baseline and at weeks 24, 48, 96 and 144 to evaluate lumbar spine and femoral neck (hip) BMD.

RESULTS

At baseline, 33 patients (55.9%) had low BMD (T-score < -1.0) and of these eight had osteoporosis (T-score < -2.5). Spine BMD declined in both arms until week 24, before stabilizing. In the NRTI-sparing arm, the mean percentage change from baseline was -2.7% [95% confidence interval (CI) -3.9 to -1.4] at week 24 and -2.5% (95% CI -5.4 to 0.3) at week 144, compared with -3.2% (95% CI -4.4 to -2.1) and -1.9% (95% CI -3.5 to -0.3) in the protease inhibitor-sparing arm. Hip BMD declined until week 48 before stabilizing. In the NRTI-sparing arm, BMD had decreased by -5.1% (95% CI -7.1 to -3.1) at week 48 and -4.5% (95% CI -6.9 to -2.1) at week 144, compared with -6.1% (95% CI -8.2 to -4.0) and -5.0% (95% CI -6.8 to -3.1) in the protease inhibitor-sparing arm. There were no significant differences between arms. Low baseline CD4 cell count was independently associated with spine (P=0.007) and hip (P=0.04) BMD loss and low body mass index with hip BMD loss (P=0.03).

CONCLUSION

Spine and hip BMD declined rapidly 24 to 48 weeks after initiating HAART, independent of the assigned drug class, but thereafter BMD values remained stable.

Position of the American Dietetic Association: Nutrition Intervention and Human Immunodeficiency Virus Infection

It is the position of the American Dietetic Association that efforts to optimize nutritional status through individualized medical nutrition therapy, assurance of food and nutrition security, and nutrition education are essential to the total system of health care available to people with human immunodeficiency virus (HIV) infection throughout the continuum of care. Broad-based efforts to improve health care access and treatment have stabilized HIV prevalence levels in many parts of the world and led to longer survival for people living with HIV infection. Confounding clinical and social issues, such as medication interactions, comorbidities, wasting, lipodystrophy, food insecurity, aging, and other related conditions further complicate disease management. With greater understanding of the mechanisms of HIV disease and its impact on body function, development of new treatments, and wider ranges of populations affected, the management of chronic HIV infection continues to become more complex and demanding. Achievement of food and nutrition security and management of nutrition-related complications of HIV infection remain significant challenges for clients with HIV infection and health care professionals. Registered dietitians and dietetic technicians, registered, should integrate their efforts into the overall health care strategies to optimize their clinical and social influence for people living with HIV infection.

Bone changes and fracture risk in individuals infected with HIV

The life expectancy of individuals infected with HIV has improved greatly since the institution of combination antiretroviral therapy. However, many metabolic derangements have been discovered with long-term combination antiretroviral treatment, including lipodystrophy; insulin resistance; and, more recently, abnormal bone metabolism. It is well-documented that bone mineral density (BMD) in HIV-positive patients is lower compared with the expected BMD in non-HIV-positive patients. The underlying cause of lower BMD is unknown but is thought to be a multifactorial process. Conflicting evidence exists regarding the effect of antiretroviral exposure and duration of treatment, antiretroviral type, and cumulative HIV viral exposure on bone health. Here we review the bone changes that occur with HIV infection and treatment.

Antiretroviral therapy and bone mineral measurements in HIV-infected youths

Reduced bone mass measurements are often found in HIV-infected youths. Both in vitro and human studies demonstrated a role of antiretroviral treatment in determining bone mass alteration. Nevertheless, the data regarding the responsibility of different antiretroviral drugs on bone health in children and adolescents are highly controversial. The purpose of the current study was to relate antiretroviral treatment to bone mass measurements in a large cohort of HIV-infected children and adolescents. Bone mineral content (BMC) was measured in 86 HIV-infected youths (aged 4.8-22.1 years), and in 194 healthy controls (aged 4.9-21.9 years). Fifteen patients were naive to antiretroviral treatment, 11 were receiving a dual nucleoside reverse transcriptase inhibitor (NRTIs) combination, 32 a protease inhibitor (PI)-based antiretroviral treatment, and 28 a non-nucleoside reverse transcriptase inhibitor (NNRTIs)-based regimen. Comparisons between healthy and HIV-infected children and adolescents have been performed by multiple regression analyses to correct for differences in age, sex, and anthropometric measurements. Patients receiving a PI-based treatment had lumbar spine and whole body BMC values significantly lower than healthy children (P<0.05). BMC measurements of patients on other therapeutic regimens or naive to antiretroviral treatment did not differ significantly from those of healthy children. Among patients receiving a PI-based regimen, those receiving full dose Ritonavir had significantly lower lumbar spine BMC values compared to other patients. Lumbar spine and whole body BMC measurements of patients receiving a Stavudine-containing regimen were lower compared to healthy controls, naive patients, and patients on other antiretroviral regimens. Multivariate analyses showed that patients receiving both Stavudine and full dose Ritonavir had significantly lower BMC values both at the lumbar spine (P=0.0033), and in the whole skeleton (P=0.05). In conclusion, antiretroviral treatment may have a detrimental effect on bone health of HIV-infected youths: the use of Ritonavir full dose alone or in combination with Stavudine is associated to lower bone mass measurements. The use of antiretroviral regimens including these drugs should thus be monitored closely in HIV-infected youths.

HIV and bone mineral density

PURPOSE OF REVIEW

This review details the clinical aspects and pathogenesis of low bone mineral density (BMD) in HIV, discusses broad management issues and outlines areas in which our understanding of this condition is incomplete.

RECENT FINDINGS

Low BMD is prevalent in HIV-infected patients, with traditional risk factors, HIV infection and exposure to antiretroviral therapy all contributing. The role of specific antiretrovirals in the development of low BMD remains controversial, but most changes arise at either antiretroviral therapy initiation or switch.

SUMMARY

Further research is needed to clarify mechanisms underlying low BMD in HIV, whether low BMD will translate to increased fractures and to determine the correct therapeutic approach to low BMD in HIV, particularly in younger HIV-infected patients.

Short-term bone loss in HIV-infected premenopausal women

BACKGROUND

Low bone mineral density (BMD) has been reported in HIV+ women, but less is known about the longitudinal evolution of BMD and fracture incidence.

METHODS

In 100 HIV+ and 68 HIV- premenopausal women in the Women's Interagency HIV Study, BMD was measured by dual energy x-ray absorptiometry at the femoral neck (FN) and lumbar spine (LS) at index visit and after a median of 2.5 years.

RESULTS

In HIV+ women, BMD at index visit was normal but 5% lower at the LS and FN than in HIV- women. Annual percent decrease in BMD did not differ between HIV+ and HIV- women at the LS (-0.8% +/- 0.2% vs -0.4% +/- 0.2%, P = 0.20) or FN (-0.8% +/- 0.3% vs -0.6% +/- 0.3%, P = 0.56) and remained similar after adjustment for age, weight, and BMD at index visit. Among HIV+ women, bone loss was associated with vitamin D deficiency and opiate use but not with use or class of antiretrovirals. Incidence of self-reported fracture was 0.74 per 100 person-years in HIV+ women and similar in HIV- women.

CONCLUSIONS

In premenopausal HIV+ women, index BMD was lower than comparable HIV- women; however, rates of bone loss at the LS and FN were similar over 2.5 years of observation, irrespective of antiretroviral therapy.

Low bone mass and high bone turnover in postmenopausal human immunodeficiency virus-infected women

CONTEXT

Low bone mineral density (BMD) is commonly reported in young men and women with HIV infection, and fracture rates may be higher. With effective antiretroviral therapy (ART), the HIV population is aging. However, little is known about the skeletal status of postmenopausal women.

OBJECTIVE

We aimed to assess the effects of HIV infection and ART on BMD and bone turnover in postmenopausal minority women.

DESIGN, SETTING, AND PATIENTS

A prospective cohort study was performed in 92 HIV+ and 95 HIV- postmenopausal Hispanic and African-American women.

MAIN OUTCOME MEASURES

We measured BMD by dual-energy x-ray absorptiometry, fracture prevalence, serum levels of inflammatory cytokines (TNFalpha, IL-6), bone turnover markers, calciotropic hormones, and estrone.

RESULTS

HIV+ women were younger (56 +/- 1 vs. 60 +/- 1 yr; P < 0.01) and had lower BMI (28 +/- 1 vs. 30 +/- 1 kg/m(2); P < 0.01) and estrone levels. Prevalence of T scores below -1.0 was greater in HIV+ women at the spine (78 vs. 64%; P < 0.05), total hip (45 vs. 29%; P < 0.05), and femoral neck (64 vs. 46%; P < 0.05), and Z scores adjusted for BMI were lower in HIV+ women at the same sites. Serum TNFalpha, N-telopeptide, and C-telopeptide were significantly higher in HIV+ than HIV- women, particularly those receiving ART. HIV+ status was independently and negatively associated with spine and hip BMD after adjustment for age, ethnicity, BMI, and alcohol.

CONCLUSION

The lower BMD, higher prevalence of low BMD, and higher levels of bone turnover markers detected in HIV+ postmenopausal minority women could place them at high risk for future fractures.

Current and Novel Inhibitors of HIV Protease

The design, development and clinical success of HIV protease inhibitors represent one of the most remarkable achievements of molecular medicine. This review describes all nine currently available FDA-approved protease inhibitors, discusses their pharmacokinetic properties, off-target activities, side-effects, and resistance profiles. The compounds in the various stages of clinical development are also introduced, as well as alternative approaches, aiming at other functional domains of HIV PR. The potential of these novel compounds to open new way to the rational drug design of human viruses is critically assessed.

Bone health in HIV infection

INTRODUCTION

Osteoporosis is among the chronic problems emerging as the human immunodeficiency virus (HIV)-positive population ages.

SOURCES OF DATA

We reviewed the English language bibliography using Pubmed 2.0, Web of Science and Embase for relevant abstracts and articles.

AREAS OF AGREEMENT

The prevalence of low bone mineral density (BMD) and fracture is increased in the HIV-positive population.

AREAS OF CONTROVERSY

The pathogenesis is multifactorial; there is some evidence that HIV infection is an independent risk factor and that highly active antiretroviral therapy has adverse skeletal effects.

GROWING POINTS

Physicians should routinely review the bone health of all HIV patients.

AREAS TIMELY FOR DEVELOPING RESEARCH

More studies of the mechanisms of bone loss, the skeletal effects of antiretroviral therapy and the therapeutic outcome of bone-protective therapy in HIV-positive individuals are needed.