Cumulative exposure to nucleoside analogue reverse transcriptase inhibitors is associated with insulin resistance markers in the Multicenter AIDS Cohort Study

Evaluating competing adverse and beneficial outcomes using a mixture model

A competing risk framework occurs when individuals have the potential to experience only one of the several mutually exclusive outcomes. Standard survival methods often overestimate the cumulative incidence of events when competing events are censored. Mixture distributions have been previously applied to the competing risk framework to obtain inferences regarding the subdistribution of an event of interest. Often the competing event is treated as a nuisance, but it may be of interest to compare adverse events against the beneficial outcome when dealing with an intervention. In this paper, methods for using a mixture model to estimate an adverse-benefit ratio curve (ratio of the cumulative incidence curves for the two competing events) and the ratio of the subhazards for the two competing events are presented. A parametric approach is described with some remarks for extending the model to include uncertainty in the event type that occurred, left truncation in order to allow for time-dependent analyses, and uncertainty in the timing of the event resulting in interval censoring. The methods are illustrated with data from an HIV clinical cohort examining whether individuals initiating effective antiretroviral therapy have a greater risk of antiretroviral discontinuation or switching compared with HIV RNA suppression.

Nonalcoholic fatty liver disease in HIV-infected patients referred to a metabolic clinic: prevalence, characteristics, and predictors

BACKGROUND

The prevalence and predictors of nonalcoholic fatty liver disease (NAFLD) in human immunodeficiency virus (HIV)-infected highly active antiretroviral therapy-experienced patients and the association of NAFLD with risk of cardiovascular disease and subclinical atherosclerosis are unknown.

METHODS

We performed a cross-sectional observational study. NAFLD was defined by liver-spleen attenuation values of <1.1 on computed tomography in persons who had neither evidence of chronic viral hepatitis nor a significant history of alcohol consumption.

RESULTS

We enrolled 225 patients; 163 (72.4%) were men. Mean (+/-SD) HIV infection duration was 145 +/- 60 months, and mean (+/-SD) body mass index (calculated as weight in kilograms divided by the square of height in meters) was 23.75 +/- 3.59. NAFLD was diagnosed in 83 patients (36.9% of the total cohort). The following variables were significantly associated with NAFLD in univariate analyses: sex, waist circumference, body mass index, cumulative exposure to nucleoside reverse-transcriptase inhibitors, visceral adipose tissue, homeostasis model assessment of insulin resistance index, serum alanine and aspartate aminotransferase levels, and ratios of total serum cholesterol to high-density lipoprotein cholesterol. Coronary artery calcium scores and a diagnosis of diabetes were not associated with NAFLD. In multivariable logistic regression analyses, factors associated (P<0.001) with NAFLD were higher serum alanine to aspartate ratio (odds ratio, 4.59; 95% confidence interval, 2.09-10.08), male sex (odds ratio, 2.49; 95% confidence interval, 1.07-5.81), greater waist circumference (odds ratio, 1.07; 95% confidence interval, 1.03-1.11), and longer nucleoside reverse-transcriptase inhibitor exposure (odds ratio, 1.12 per year of exposure; 95% confidence interval, 1.03-1.22).

CONCLUSIONS

NAFLD is common among HIV-infected persons who have the traditional risk factors for NAFLD (elevations in serum alanine level, male sex, and increased waist circumference) apparent. Exposure to nucleoside reverse-transcriptase inhibitors was an independent risk factor for NAFLD, with an 11% increase in the odds ratio for each year of use.

Nephrotoxicity associated with antiretroviral therapy in HIV-infected patients

BACKGROUND

With the success of modern antiretroviral therapies in increasing longevity of patients with HIV infection, chronic conditions including renal disease have assumed a greater importance in patient management. Some antiretroviral therapies have themselves been identified to have clinically significant nephrotoxicity.

OBJECTIVE

To review the risk factors and mechanisms for renal toxicity of antiretroviral drugs, and their impact on the clinical management of patients with HIV.

METHODS

Current literature and HIV treatment guidelines are reviewed.

RESULTS/CONCLUSIONS

Background rates of renal disease and associated risk factors are significant in the HIV clinic population, and renal function should be assessed in all HIV-infected patients. Modern HIV treatment regimens have a relatively low but clinically significant nephrotoxic potential; therefore, renal function should be evaluated on an ongoing basis in patients receiving antiretroviral therapy.

Low CD4+ T-cell count as a major atherosclerosis risk factor in HIV-infected women and men

OBJECTIVE

To assess the association of HIV infection, HIV disease parameters (including CD4+ T-cell counts, HIV viral load, and AIDS) and antiretroviral medication use with subclinical carotid artery atherosclerosis.

DESIGN

Cross-sectional study nested within a prospective cohort study.

METHODS

Among participants in the Women's Interagency HIV Study (1331 HIV-infected women, 534 HIV-uninfected women) and Multicenter AIDS Cohort Study (600 HIV-infected men, 325 HIV-uninfected men), we measured subclinical carotid artery lesions and common carotid artery intima-media thickness using B-mode ultrasound. We estimated adjusted mean carotid artery intima-media thickness differences and prevalence ratios for carotid lesions associated with HIV-related disease and treatments, with multivariate adjustment to control for possible confounding variables.

RESULTS

Among HIV-infected individuals, a low CD4+ T-cell count was independently associated with an increased prevalence of carotid lesions. Compared with the reference group of HIV-uninfected individuals, the adjusted prevalence ratio for lesions among HIV-infected individuals with CD4+ T-cell count less than 200 cells/mul was 2.00 (95% confidence interval, 1.22-3.28) in women and 1.74 (95% confidence interval, 1.04-2.93) in men. No consistent association of antiretroviral medications with carotid atherosclerosis was observed, except for a borderline significant association between protease inhibitor use and carotid lesions in men (with no association among women). History of clinical AIDS and HIV viral load were not significantly associated with carotid atherosclerosis.

CONCLUSION

Beyond traditional cardiovascular disease risk factors, low CD4+ T-cell count is the most robust risk factor for increased subclinical carotid atherosclerosis in HIV-infected women and men.

Subclinical coronary atherosclerosis, HIV infection and antiretroviral therapy: Multicenter AIDS Cohort Study

OBJECTIVE

To evaluate the association of HIV infection and cumulative exposure to highly active antiretroviral therapy (HAART) with the presence and extent of coronary artery calcification (CAC).

DESIGN

A cross-sectional study of 947 male participants (332 HIV-seronegative, 84 HAART-naive and 531 HAART-experienced HIV-infected) from the Multicenter AIDS Cohort Study.

METHODS

The main outcome was CAC score calculated as the geometric mean of the Agatston scores of two computed tomography replicates. Presence of CAC was defined as calcification score above 10, and extent of CAC by the score for those with CAC present. Multivariable regression was used to evaluate the association between HIV infection and HAART and presence and extent of calcification.

RESULTS

Increasing age was most strongly associated with both prevalence and extent of CAC for all study groups. After adjustment for age, race, family history, smoking, high-density lipoprotein-C, low-density lipoprotein-C and hypertension, HIV infection (odds ratio, 1.35; 95% confidence interval, 0.70, 2.61) and long-term HAART use (odds ratio, 1.33; 95% confidence interval, 0.87, 2.05) increased the odds for presence of CAC. In contrast, after adjustment for these covariates, the extent of CAC was lower among HAART users. Among those not taking lipid-lowering therapy, HAART usage of at least 8 years was associated with significantly reduced CAC scores (relative CAC score, 0.43; 95% confidence interval, 0.24, 0.79).

CONCLUSION

HAART use may have different effects on the presence and extent of coronary calcification. Although prevalence of calcification was marginally increased among long-term HAART users, the extent of calcification was significantly reduced among HAART users compared with HIV-seronegative controls.

Safety of stavudine in the treatment of HIV infection with a special focus on resource-limited settings

BACKGROUND

Western randomized trials and prospective cohorts in resource-limited settings have proven virological success with stavudine-based highly active antiretroviral therapy. However, stavudine is no longer recommended in first-line treatments in these two settings due to its intrinsic toxicities and side effects. Yet it remains a cornerstone of treatment in resource-limited settings, due to lack of alternatives and its availability in generic fixed-dose combinations.

OBJECTIVE

To review the toxic effects of stavudine and their prevention and management strategies, especially in resource-limited settings.

METHODS

Data from clinical and pharmacological trials in Western countries, as well as prospective cohorts in resource-limited settings, were reviewed.

CONCLUSION

Initiating or switching to less toxic nucleoside analogues whenever possible, or lowering stavudine doses to 30 mg b.i.d., is strongly recommended.

HIV therapy, metabolic syndrome, and cardiovascular risk

People with HIV infection have metabolic abnormalities that resemble metabolic syndrome (hypertriglyceridemia, low high-density lipoprotein cholesterol, and insulin resistance), which is known to predict increased risk of cardiovascular disease (CVD). However, there is not one underlying cause for these abnormalities and they are not linked to each other. Rather, individual abnormalities can be affected by the host response to HIV itself, specific HIV drugs, classes of HIV drugs, HIV-associated lipoatrophy, or restoration to health. Furthermore, one component of metabolic syndrome, increased waist circumference, occurs less frequently in HIV infection. Thus, HIV infection supports the concept that metabolic syndrome does not represent a syndrome based on a common underlying pathophysiology. As might be predicted from these findings, the prevalence of CVD is higher in people with HIV infection. It remains to be determined whether CVD rates in HIV infection are higher than might be predicted from traditional risk factors, including smoking.

Use of nucleoside reverse transcriptase inhibitors and risk of myocardial infarction in HIV-infected patients enrolled in the D:A:D study: a multi-cohort collaboration

BACKGROUND

Whether nucleoside reverse transcriptase inhibitors increase the risk of myocardial infarction in HIV-infected individuals is unclear. Our aim was to explore whether exposure to such drugs was associated with an excess risk of myocardial infarction in a large, prospective observational cohort of HIV-infected patients.

METHODS

We used Poisson regression models to quantify the relation between cumulative, recent (currently or within the preceding 6 months), and past use of zidovudine, didanosine, stavudine, lamivudine, and abacavir and development of myocardial infarction in 33 347 patients enrolled in the D:A:D study. We adjusted for cardiovascular risk factors that are unlikely to be affected by antiretroviral therapy, cohort, calendar year, and use of other antiretrovirals.

FINDINGS

Over 157,912 person-years, 517 patients had a myocardial infarction. We found no associations between the rate of myocardial infarction and cumulative or recent use of zidovudine, stavudine, or lamivudine. By contrast, recent-but not cumulative-use of abacavir or didanosine was associated with an increased rate of myocardial infarction (compared with those with no recent use of the drugs, relative rate 1.90, 95% CI 1.47-2.45 [p=0.0001] with abacavir and 1.49, 1.14-1.95 [p=0.003] with didanosine); rates were not significantly increased in those who stopped these drugs more than 6 months previously compared with those who had never received these drugs. After adjustment for predicted 10-year risk of coronary heart disease, recent use of both didanosine and abacavir remained associated with increased rates of myocardial infarction (1.49, 1.14-1.95 [p=0.004] with didanosine; 1.89, 1.47-2.45 [p=0.0001] with abacavir).

INTERPRETATION

There exists an increased risk of myocardial infarction in patients exposed to abacavir and didanosine within the preceding 6 months. The excess risk does not seem to be explained by underlying established cardiovascular risk factors and was not present beyond 6 months after drug cessation.

Seven-year efficacy of a lopinavir/ritonavir-based regimen in antiretroviral-naïve HIV-1-infected patients

OBJECTIVE

Evaluate efficacy and tolerability of lopinavir/ritonavir (LPV/r) plus stavudine and lamivudine long term in antiretroviral-naïve patients.

DESIGN

Open-label follow-up of prospective, randomized, multicenter trial.

METHOD

Antiretroviral-naïve HIV-infected subjects (N = 00) received of 3 doses of LPV/r plus stavudine and lamivudine for 48 weeks then received LPV/r soft-gel capsules 400/00 mg plus stavudine and lamivudine. After 6 years, subjects replaced stavudine with tenofovir.

RESULTS

At 7 years, by intent-to-treat analysis, 61 % had plasma HIV-RNA <400 copies/mL and 59% had < 50 copies/mL. Thirty-nine subjects discontinued treatment due to adverse events (n = 6), personal/other reasons (0), loss to follow-up (9), and noncompliance (4). Among 28 subjects qualifying for drug resistance testing, no protease inhibitor or stavudine resistance was observed and 4 showed lamivudine resistance. Most common drug-related moderate or severe adverse events were diarrhea (28%), nausea (6%), and abdominal pain (11 %). Subjects who received stavudine (median 6.6 years) and switched to tenofovir demonstrated significant improvements in total cholesterol (p = .009), triglycerides (p = .023), apolipoprotein C-III (p < .001 ), adiponectin (p = .008), fasting insulin (p = .04), and leptin (p = .03).

CONCLUSION

LPV/r-based therapy demonstrated sustained efficacy with no protease inhibitor or stavudine resistance through 7 years in antiretroviral-naïve patients. Switching from stavudine to tenofovir resulted in significant improvements in multiple metabolic parameters.

Therapy insight: Body-shape changes and metabolic complications associated with HIV and highly active antiretroviral therapy

Increasingly effective therapies for HIV infection are now available. These treatments, referred to collectively as highly active antiretroviral therapy, comprise various combinations of anti-HIV drugs from different drug classes. Recently, a range of metabolic complications have emerged as important toxicities in treated patients. Complications present as abnormalities of body-fat mass distribution in association with an often significant dyslipidemia and glucose homeostasis dysregulation. The body-shape changes, manifesting as peripheral lipoatrophy or central lipohypertrophy, can have a negative impact on quality of life and consequently on adherence to treatment. The combination of central lipohypertrophy, dyslipidemia and insulin resistance is associated with accelerated rates of atherosclerosis and other potentially significant long-term effects. The pathogenesis of these effects is complex and is still being actively investigated. Possible contributing factors relate to host characteristics, HIV viral parameters and specific effects of anti-HIV drugs on adipose-tissue biology and on intermediary metabolism. Management of these complications involves manipulation of the anti-HIV drugs using an understanding of their particular effects on lipid and glucose metabolism, in association with standard therapeutic interventions. Individualized approaches, taking into consideration quality-of-life issues, and assessment of potential cardiovascular risks, are now an important component of effective care of HIV-infected patients.

Metabolic function and the prevalence of lipodystrophy in a population of HIV-infected African subjects receiving highly active antiretroviral therapy

OBJECTIVE

This study measured the prevalence of lipodystrophy and the metabolic effects of highly active antiretroviral therapy (HAART) in HIV-infected African subjects.

METHODS

Prevalence was measured in 571 Rwandans receiving HAART for > or = 6 months. Metabolic variables were measured in 100 HIV-positive adults with lipodystrophy, 50 HIV-positive nonlipodystrophic adults, and 50 HIV-negative controls.

RESULTS

A HAART regimen of stavudine, lamivudine, and nevirapine was used by 81.6% of subjects; none received protease inhibitors. Lipodystrophy was observed in 34% (48.5% in urban groups and 17.3% in rural groups) of subjects, with a prevalence of 69.6% in those receiving HAART for >72 weeks. Peripheral lipoatrophy combined with abdominal lipohypertrophy was observed in 72% of lipodystrophic subjects. HIV-positive adults with lipodystrophy had a significantly higher waist-to-hip ratio (WHR; 0.99 +/- 0.05 vs. 0.84 +/- 0.03: P < 0.0005) than HIV-positive nonlipodystrophic adults. Total cholesterol concentrations (median [interquartile range], mmol/L) were significantly higher in the HIV-positive adults with lipodystrophy (3.60 [1.38]) than in HIV-positive nonlipodystrophic adults (3.19 [0.65]; P < 0.005) and control (3.13 [0.70]; P < 0.0005) groups. Impaired fasting glucose was observed in 18% of HIV-positive adults with lipodystrophy, 16% of HIV-positive nonlipodystrophic adults, and 2% of controls, but insulin levels did not differ.

CONCLUSIONS

African subjects with lipodystrophy have increased WHR, glucose, and cholesterol levels. Glucose concentrations are also elevated in nonlipodystrophic HIV-positive subjects. Therefore, factors other than body fat redistribution contribute to the glucose intolerance.

Magnetic resonance spectroscopy of hepatic lipid content and associated risk factors in HIV infection

BACKGROUND

Liver-related illness is increasingly recognized as a source of morbidity in HIV-infected patients. Fatty infiltration of the liver is potentially an important consequence of HIV and treatment with antiretroviral (ARV) therapy.

OBJECTIVE

The aim of the present study was to evaluate HIV-infected men and women for hepatic steatosis using noninvasive magnetic resonance spectroscopy (MRS) and to assess the relationship between liver fat content, insulin resistance, and other associated risk factors.

METHODS

We examined 33 consecutively recruited HIV-infected adults without specific referral for liver disease. Subjects with alcohol abuse within 3 years or end-stage liver disease were excluded. The primary clinical measures were hepatic fat content measured by MRS, homeostasis model for assessment of insulin resistance (HOMA-IR), and body fat distribution assessed by cross-sectional computed tomography.

RESULTS

We identified hepatic steatosis (liver fat content > or =5%) in 42% of subjects. Hepatic fat content was significantly correlated with HOMA-IR (r = 0.68, P < 0.0001) and increased visceral adiposity (r = 0.60, P < 0.001). Subjects with steatosis had significantly increased body mass index and alanine aminotransferase and triglyceride levels, with lower muscle attenuation (ie, increased intramuscular fat) compared to subjects without steatosis. However, steatosis was not related to duration of HIV, ARV exposure, or HCV coinfection.

CONCLUSIONS

These data suggest that hepatic steatosis may be very common in HIV, not limited to those with HCV coinfection, and may play an important role in the metabolic profile among HIV-infected men and women.

Zidovudine/lamivudine contributes to insulin resistance within 3 months of starting combination antiretroviral therapy

BACKGROUND

Patients with antiretroviral therapy (ART)-associated lipodystrophy frequently have disturbances in glucose metabolism associated with insulin resistance. It is not known whether changes in body composition are necessary for the development of these disturbances in ART-naive patients starting treatment with different combination ART regimens.

METHODS

Glucose metabolism and body composition were assessed before and after 3 months of ART in a prospective randomized clinical trial of HIV-1-positive ART-naive men taking lopinavir/ritonavir within either a nucleoside reverse transcriptase inhibitor (NRTI)-containing regimen (zidovudine/lamivudine; n = 11) or a NRTI-sparing regimen (nevirapine; n = 9). Glucose disposal, glucose production and lipolysis were measured after an overnight fast and during a hyperinsulinaemic-euglycaemic clamp using stable isotopes. Body composition was assessed by computed tomography and dual-energy X-ray absorptiometry.

RESULTS

In the NRTI-containing group, body composition did not change significantly in 3 months; insulin-mediated glucose disposal decreased significantly (25%; P < 0.001); and fasting glycerol turnover increased (22%; P < 0.005). Hyperinsulinaemia suppressed glycerol turnover equally before and after treatment. The disturbances in glucose metabolism were not accompanied by changes in adiponectin or other glucoregulatory hormones. In contrast, glucose metabolism did not change in the NRTI-sparing arm. Glucose disposal significantly differed over time between the arms (P < 0.01).

CONCLUSIONS

Treatment for 3 months with a NRTI-containing, but not a NRTI-sparing, regimen resulted in a 25% decrease in insulin-mediated glucose disposal and a 22% increase in fasting lipolysis. In the absence of discernable changes in body composition, NRTI may directly affect glucose metabolism, the mechanism by which remains to be elucidated.

Cardiovascular risk and choice of HIV drug regimen

Since the introduction of combination antiretroviral therapy (cART), there have been many conflicting reports linking its use to the development of cardiovascular disease (CVD). Most antiretroviral drugs have been associated with the development of lipid abnormalities to some degree. However, whereas several large observational studies have reported a link between the use of cART (particularly protease inhibitors) and CVD, evidence linking specific antiretroviral drugs to CVD is limited. Much of the evidence linking cART to the development of dyslipidemia derives from randomized trials. However, given the relative infrequency of CVD in most HIV-positive populations, these may be inadequately powered to demonstrate a link with clinical events. In contrast, large observational studies have greater power to describe the development of clinical events but may be affected by bias. This review will describe the current literature linking cART to CVD as well as the limitations of some of the published studies.

Longitudinal increases in waist circumference are associated with HIV-serostatus, independent of antiretroviral therapy

BACKGROUND

The relative contributions of the different classes of antiretroviral therapy (ART), HIV infection per se, and aging to body shape changes in HIV-infected patients have not been clearly defined in longitudinal studies.

METHODS

Since September 1999, men enrolled in the Multicenter AIDS Cohort Study have undergone measurements of body mass index (BMI) and body circumferences at each semi-annual visit. The effect of HIV-serostatus and cumulative exposure to the three major ART classes on changes in anthropomorphic measurements occurring between 1999 and 2004 among HIV-infected and HIV-uninfected men were determined using linear mixed effects regression models.

RESULTS

At baseline, average BMI and circumference measurements were greater in HIV-uninfected men (n = 392) than HIV-infected men (n = 661) (BMI, 27.3 versus 25.3 kg/m; waist, 96.4 versus 90.2 cm; hip 101.3 versus 95 cm, thigh 54.1 versus 50.8 cm; arm 33.3 versus 31.7 cm, P < 0.001 for each comparison). Cumulative nucleoside reverse transcriptase inhibitor (NRTI) exposure, but not protease inhibitor or non-nucleoside reverse transcriptase inhibitor exposure, was associated with statistically significant changes in BMI (-0.11 +/- 0.04 kg/m per year) and in circumferences of waist (-0.27 +/- 0.07 cm/year), hip (-0.24 +/- 0.05 cm/year), and thigh (-0.16 +/- 0.03 cm/year) over the 5 years of follow-up. Independent of ART exposure, HIV-infected men had a more rapid increase in waist circumference over the study interval than did the HIV-uninfected men (difference 0.33 +/- 0.15 cm/year, P = 0.02).

CONCLUSION

Cumulative NRTI therapy was associated with longitudinal decreases in body circumference measurements, whereas HIV-serostatus was associated with increases in waist circumference independent of ART.

Antiretroviral therapy exposure and incidence of diabetes mellitus in the Women's Interagency HIV Study

OBJECTIVE

To determine the incidence of diabetes mellitus (DM) in a nationally representative cohort of HIV-infected women and a comparison group of HIV-uninfected women.

DESIGN

A prospective study between October 2000 and March 2006 of 2088 participants from the Women's Interagency HIV Study who did not have evidence of DM at enrollment (1524 HIV infected and 564 HIV uninfected).

METHODS

Incident DM was defined as either having fasting glucose > or = 1.26 g/l, reporting antidiabetic medication, or reporting DM diagnosis (with subsequent confirmation by fasting glucose > or = 1.26 g/l or reported antidiabetic medication); all were assessed at semi-annual study visits.

RESULTS

DM developed in 116 HIV-infected and 36 HIV-uninfected women over 6802 person-years. HIV-infected women reporting no recent antiretroviral therapy had a DM incidence rate of 1.53/100 person-years; those reporting HAART containing a protease inhibitor (PI) had a rate of 2.50/100 person-years and those reporting non-PI-containing HAART a rate of 2.89/100 person-years. None of these rates differed from the HIV-uninfected women (1.96/100 person-years) substantially or beyond levels expected by chance. Among HIV-infected women, longer cumulative exposure to nucleoside reverse transcriptase inhibitors (NRTI) was associated with an increased risk of DM incidence compared with no NRTI exposure: relative hazard (RH) 1.81 [95% confidence interval (CI), 0.83-3.93] for > 0 to 3 years exposure and RH 2.64 (95% CI, 1.11-6.32) for > 3 years exposure.

CONCLUSION

Longer cumulative exposure to NRTI was associated with increased DM incidence in HIV-infected women. Regular DM monitoring is advisable because NRTI form the backbone of effective antiretroviral therapy.

Metabolic complications of HIV infection and its therapy in children

HIV infection has become a chronic disease in pediatric patients, with the potential for longer term survival and exposure to combination antiretroviral therapy for two decades longer than HIV-positive adults. However, body shape and metabolic abnormalities are frequently observed during antiretroviral therapy. These abnormalities have been poorly evaluated in HIV-infected children and their long-term consequences are not yet well assessed. This review summarizes our current understanding of the epidemiology, diagnosis and management of body shape abnormalities, dyslipidemia, disorders of glucose metabolism and vascular dysfunction in HIV-infected children and adolescents.

Insulin resistance, glucose intolerance and diabetes mellitus in HIV-infected patients

An increased prevalence of insulin resistance, glucose intolerance and diabetes has been reported in HIV infection in the highly active antiretroviral therapy (HAART) era. This development might be clinically significant because of its association with cardiovascular morbidity and mortality as well as the therapeutic challenges of managing polypharmacy. The development of insulin resistance, glucose intolerance and diabetes could be related to the underlying HIV infection, the contribution of different antiretroviral agents, treatment-associated weight gain, immune restoration, as well as the non-HIV related factors. Dissecting these factors in clinical practice might be difficult. Clinical studies include short-term treatments in healthy, non-HIV-infected individuals; randomized, controlled trials; comparative studies of different HAART regimens; and randomized studies of switching regimens in patients with viral suppression and stable immune function. This article reviews the latest knowledge regarding the epidemiology, pathogenesis, prevention and treatment of insulin resistance, glucose intolerance and diabetes mellitus in HIV-infected individuals.

Factors associated with the incidence of type 2 diabetes mellitus in HIV-infected participants in the Swiss HIV Cohort Study

BACKGROUND

Human immunodeficiency virus (HIV)-infected persons may be at increased risk for developing type 2 diabetes mellitus because of viral coinfection and adverse effects of treatment.

METHODS

We studied associations of new-onset diabetes mellitus with hepatitis B virus and hepatitis C virus coinfections and antiretroviral therapy in participants in the Swiss HIV Cohort Study, using Poisson regression.

RESULTS

A total of 123 of 6513 persons experienced diabetes mellitus during 27,798 person-years of follow-up (PYFU), resulting in an incidence of 4.4 cases per 1000 PYFU (95% confidence interval [CI], 3.7-5.3 cases per 1000 PYFU). An increased incidence rate ratio (IRR) was found for male subjects (IRR, 2.5; 95% CI, 1.5-4.2), older age (IRR for subjects >60 years old, 4.3; 95% CI, 2.3-8.2), black (IRR, 2.1; 95% CI, 1.1-4.0) and Asian (IRR, 4.9; 95% CI, 2.2-10.9) ethnicity, Centers for Disease Control and Prevention disease stage C (IRR, 1.6; 95% CI, 1.04-2.4), and obesity (IRR, 4.7; 95% CI, 3.1-7.0), but results for hepatitis C virus infection or active hepatitis B virus infection were inconclusive. Strong associations were found for current treatment with nucleoside reverse-transcriptase inhibitors (IRR, 2.22; 95% CI, 1.11-4.45), nucleoside reverse-transcriptase inhibitors plus protease inhibitors (IRR, 2.48; 95% CI, 1.42-4.31), and nucleoside reverse-transcriptase inhibitors plus protease inhibitors and nonnucleoside reverse-transcriptase inhibitors (IRR, 3.25; 95% CI, 1.59-6.67) but were not found for treatment with nucleoside reverse-transcriptase inhibitors plus nonnucleoside reverse-transcriptase inhibitors (IRR, 1.47; 95% CI, 0.77-2.82).

CONCLUSIONS

In addition to traditional risk factors, current treatment with protease inhibitor- and nucleoside reverse-transcriptase inhibitor-containing regimens was associated with the risk of developing type 2 diabetes mellitus. Our study did not find a significant association between viral hepatitis infection and risk of incident diabetes.

Long-Term Body Composition and Metabolic Changes in Antiretroviral Naive Persons Randomized to Protease Inhibitor-, Nonnucleoside Reverse Transcriptase Inhibitor-, or Protease Inhibitor Plus Nonnucleoside Reverse Transcriptase Inhibitor-Based Strategy

OBJECTIVE

To assess changes in metabolic parameters and body composition among 422 antiretroviral-naive patients randomized to 3 antiretroviral therapy (ART) strategies: protease inhibitor (PI; n = 141)-, nonnucleoside reverse transcriptase inhibitor (NNRTI; n = 141)-, or PI + NNRTI (n = 140)-based strategies with a median follow-up of 5 years.

METHODS

At baseline and 1-month (metabolic parameters only) and 4-month follow-up intervals, fat-free mass (FFM) and total body fat were calculated, anthropometric measurements were performed, and fasting metabolic parameters were obtained. Rates of change and mean change were compared.

RESULTS

The PI + NNRTI strategy resulted in greater increases in triglycerides and low-density lipoprotein cholesterol compared with the PI and the NNRTI strategies (P < 0.005), with no differences between the PI and NNRTI strategies. High-density lipoprotein cholesterol increased significantly more in the NNRTI strategy than in the PI strategy (P < 0.005). Insulin and insulin resistance increased similarly with all 3 strategies. Changes in total and regional body composition (loss of subcutaneous tissue area and gains in FFM, nonsubcutaneous tissue area, and visceral tissue area) were observed but did not differ by strategy.

CONCLUSIONS

Long-term follow-up of participants initiating 3 ART strategies demonstrated similar changes in total and regional fat, with no differences by ART strategy. The differential effects on lipid metabolism by strategy and the overall increases in insulin and insulin resistance with all 3 strategies necessitate close monitoring of patients on ART.

Hepatitis C virus infection is associated with insulin resistance among older adults with or at risk of HIV infection

OBJECTIVES

To determine the associations of hepatitis C virus (HCV) infection with insulin resistance and abnormal glucose tolerance in a cohort of older adults with or at risk of HIV infection.

DESIGN

A cross-sectional study of 267 HIV-infected and 179 at-risk-uninfected adults without a history of diabetes mellitus.

METHODS

HCV antibody assays and RNA levels were performed to assess HCV status. Antiretroviral use, family history of diabetes, sedentary behavior, and sociodemographic data were obtained using standardized interviews. Fasting insulin levels and oral glucose tolerance tests were performed to assess two outcomes, the homeostasis model assessment of insulin resistance and abnormal glucose tolerance [impaired glucose tolerance (IGT) or diabetes].

RESULTS

Of 446 participants, 265 (59%) were HCV seropositive; of these, 199 (75%) had detectable HCV-RNA levels. Insulin resistance was greater among HCV-seropositive compared with seronegative participants, adjusting for body mass index, Hispanic ethnicity, age greater than 55 years, sedentary behavior (watching television > 4 h/day), HIV status, HAART, and protease inhibitor (PI) use. Ninety-eight participants (22%) had abnormal glucose tolerance (69 with IGT and 29 with diabetes). Among HIV-infected participants, 25% were on non-PI HAART and 52% were on PI HAART, but HAART and PI use were not associated with insulin resistance or abnormal glucose tolerance. Among obese participants, abnormal glucose tolerance was more common in HCV-seropositive than seronegative individuals, whereas among non-obese participants there was no association.

CONCLUSION

The potential impact of HCV co-infection and obesity on glucose metabolism should be recognized in clinical care, and addressed in future research studies of HIV-infected individuals.

Metabolic syndrome in HIV-infected patients from an urban, midwestern US outpatient population

BACKGROUND

The association between the use of highly active antiretroviral therapy (HAART) and an increased risk of metabolic syndrome and cardiovascular disease remains unclear.

METHODS

We conducted a prospective, cross-sectional study of the risk factors associated with metabolic syndrome and cardiovascular disease among patients from an urban outpatient human immunodeficiency virus (HIV) clinic. Evaluation included laboratory data that were obtained after an overnight fast and a health survey that assessed traditional risk factors associated with cardiovascular disease, HIV-related factors, and comorbidities. Data collected were compared with data files from a cohort from the National Health and Nutrition Examination Survey (NHANES; 2001-2002) of persons who were seronegative for HIV infection who were matched for age, sex, race, and tobacco use.

RESULTS

Four hundred seventy-one HIV-infected subjects provided complete data. The overall prevalence of metabolic syndrome was similar between the group HIV-infected patients and the group of persons who were seronegative for HIV infection (25.5% vs. 26.5%, respectively), although the HIV-infected patients had a significantly smaller waist circumference, lower body mass index, lower high-density lipoprotein cholesterol levels, higher triglyceride levels, and lower glucose levels, compared with the subjects from the NHANES cohort. Framingham 10-year risk scores were also similar between the 2 groups. HIV-infected patients with metabolic syndrome were more likely to be diabetic, older, and white and have a high CD4 cell count and body mass index, compared with patients without metabolic syndrome (P<.05 for all). The type or duration of antiretroviral therapy was not an independent risk factor for metabolic syndrome.

CONCLUSIONS

The prevalence of metabolic syndrome is high among HIV-infected persons, but not higher than the prevalence among HIV-uninfected persons. Traditional risk factors play a more significant role in the development of metabolic syndrome than do HIV treatment-associated factors.

Metabolic abnormalities in HIV-infected patients: An update

In recent years, substantial progress has been made in our understanding of the pathogenesis, risk factors, and treatment of glucose and lipid abnormalities in HIV-infected patients. Newer antiretrovirals, such as abacavir and tenofovir in the nucleoside reverse transcriptase class and atazanavir in the protease inhibitor class, have been shown to improve metabolic profiles compared to other medications. In addition, new information regarding the efficacy of glucose and lipid-lowering medications in HIV-infected patients has become available. It has also been demonstrated that aggressive risk factor modification can reduce the burden of cardiovascular disease in this population. This article reviews these recent advances in order to help providers respond to these important clinical challenges.

Current concepts in the diagnosis and management of metabolic complications of HIV infection and its therapy

Changes in fat distribution, dyslipidemia, disordered glucose metabolism, and lactic acidosis have emerged as significant challenges to the treatment of human immunodeficiency virus (HIV) infection. Over the past decade, numerous investigations have been conducted to better define these conditions, identify risk factors associated with their development, and test potential therapeutic interventions. The lack of standardized diagnostic criteria, as well as disparate study populations and research methods, have led to conflicting data regarding the diagnosis and treatment of metabolic and body shape disorders associated with HIV infection. On the basis of a review of the medical literature published and/or data presented before April 2006, we have prepared a guide to assist the clinician in the detection and management of these complications.

Mitochondrial AZT metabolism

AZT remains an important drug to combat HIV infection in combination with other nucleoside analogs. However, long-term treatment with nucleoside analogs can result in mitochondrial toxicity, which can be fatal in some forms. We review the metabolic pathway for AZT transport and phosphorylation within mitochondria and its interaction with the mitochondrial DNA polymerase, Pol-gamma. Suggested mechanisms for the mitochondrial toxicity of AZT related to this metabolism are discussed. Finally we review recent evidence that the HIV virus itself is involved in the toxicity of AZT.

Use of tenofovir disoproxil fumarate and emtricitabine combination in HIV-infected patients

With the continuing spread of HIV infection, particularly in developing countries, cost-effective treatment for its management is a high priority. Truvada (Gilead Sciences) is a single combination pill of the nucleotide reverse transcriptase inhibitors tenofovir disoproxil fumarate and emtricitabine, which is used once daily. It is anticipated to be a clinically potent combination that is free of short-term irritating toxicity. The drug has recently been licensed but there are currently little clinical efficacy data regarding its use. The limited published data have indicated that emtricitabine and lamivudine have equivalent potency, and randomised controlled trials have produced evidence of the efficacy of lamivudine combined with tenofovir disoproxil fumarate in a regimen containing either the non-nucleoside reverse transcriptase inhibitor efavirenz or a protease inhibitor lopinavir/ritonavir. In these trials, long-term durability data are available for < or = 96 weeks.

Sustained improvement of dyslipidaemia in HAART-treated patients replacing stavudine with tenofovir

OBJECTIVE

To describe the 12-month evolution of lipid profile in HIV-infected virologically suppressed patients substituting tenofovir for stavudine.

DESIGN AND METHODS

'Recover' was a prospective, multicenter, switch study conducted at 120 HIV units across Spain designed to identify single nucleoside analogue substitution due to adverse events in real practice. Tenofovir substituted stavudine in 873 adult patients. No other substitutions were allowed. This lipid sub-study included 352 randomly recruited patients with complete follow-up and lipid parameters.

MAIN OUTCOME MEASURES

Changes in fasting levels of total cholesterol (TC), high and low-density lipoprotein cholesterol (HDL-C and LDL-C), and triglycerides (TG) at 48 weeks, and their cardiovascular risk (CVR) translation.

RESULTS

At 48 weeks, there was a sustained reduction in median TC (-17.5 mg/dl; P < 0.001), LDL-C (-8.1 mg/dl; P < 0.001), and TG (-35 mg/dl; P < 0.001). HDL-C remained roughly unchanged (-0.8 mg/dl). Patients with baseline hyperlipidaemia showed greater reductions in LDL-C (-29 mg/dl; P < 0.001) and TG (-76 mg/dl; P < 0.001). The greatest TG reduction was observed in patients with severe hyper-TG (-266 mg/dl; P < 0.001). The estimated 10-year CVR decreased in all patients (P < 0.001), and to a higher extent in patients with baseline hyperlipidaemia. There was a trend towards reduction according to the use of lipid-lowering agents (11.6% to 9,9%; P = non-significant).

CONCLUSIONS

The substitution of tenofovir for stavudine causes a sustained improvement of dyslipidaemia. The reduction, although modest, is robust and sustained over time, and significantly reduces the CVR. This switch strategy is safe and contributes to an improvement in the lipid profile, especially TG, in HAART-treated patients.

Diabetes, insulin resistance, and HIV

The transformation of HIV infection into a chronically managed illness through the widespread use of highly active antiretroviral therapy has brought with it comorbid conditions such as increased risk of cardiovascular disease. Diabetes and insulin resistance have emerged as important comorbidities associated with HIV infection and the use of antiretroviral therapy. Significant inroads have been made towards understanding the etiology of insulin resistance and diabetes in association with HIV and highly active antiretroviral therapy, and there are also emerging data on the prevalence and incidence of this problem. The recognition and management of diabetes mellitus, insulin resistance, and related complications will be an important part of long-term health maintenance for HIV-infected patients.

Aging and HIV infection

With the advent of highly active antiretroviral therapy (HAART) in mid-1995, the prognosis for HIV-infected individuals has brightened dramatically. However, the conjunction of potent antiviral therapy and longer life expectancy may engender a variety of health risks that, heretofore, HIV specialists have not had to confront. The long-term effects of HIV infection itself and exposure to antiretroviral agents is unknown. Several aspects of aging, including psychiatric disease, neurocognitive impairment, and metabolic and hormonal disorders, may be influenced by chronic exposure to HIV and/or HIV therapeutics. In this paper, we discuss the health issues confronting HIV-infected older adults and areas for future research.