Use of cardiac CT angiography imaging in an epidemiology study - the Methodology of the Multicenter AIDS Cohort Study cardiovascular disease substudy

OBJECTIVE

The methodology for use of cardiac CT angiography (CTA) in low risk populations is not well defined. In order to present a reference for future studies, we present CTA methodology that is being used in an epidemiology study- the Multicenter AIDS Cohort Study (MACS).

METHODS

The Multicenter AIDS Cohort Study (MACS) is an on-going multicenter prospective, observational cohort study. The MACS Cardiovascular Disease substudy plans to enroll 800 men (n= 575 HIV seropositive and n=225 HIV seronegative) age 40-70 years for coronary atherosclerosis imaging using cardiac CTA. The protocol includes heart rate (HR) optimization with beta- blockers; use of proper field of view; scan length limitation; prospective ECG-gating using the lowest beam voltage possible. All scans are evaluated for presence, extent, and composition of coronary atherosclerosis, left atrial volumes, left ventricular volume and mass and non-coronary cardiac pathology.

RESULTS

The first 498 participants had an average radiation dose of 2.5±1.6 milliSieverts (mSv) for the cardiac CTA study. Overall quality of scans was fair to excellent in 98.6% of studies. There were three significant adverse events-two allergic reactions to contrast and one subcutaneous contrast extravasation.

CONCLUSION

Cardiac CTA was safe and afforded a low effective radiation exposure to these asymptomatic research participants and provides valuable cardiovascular endpoints for scientific analysis. The cardiac CTA methodology described here may serve as a reference for use in future epidemiology studies aiming to assess coronary atherosclerosis and cardiac anatomy in low risk populations while minimizing radiation exposure.

The impact of impaired kidney function and HIV infection on the risk of anemia

Chronic kidney disease and HIV infection both independently increase the risk of anemia. It is not known if individuals with both HIV infection and kidney dysfunction are at greater than expected risk of anemia resulting from the combined effect of these factors. Men from the Multicenter AIDS Cohort Study with AIDS-free time after 1996 were included in the analysis if they had an initial hemoglobin value greater than 13 g/dl and available serum creatinine measurements for the estimation of glomerular filtration rate. Hemoglobin data were fit parametrically using a linear mixed effects model and effects of medication use on hemoglobin levels were removed using censoring methods. The effect of both HIV infection and glomerular filtration rate less than 60 ml/min/1.73 m(2) on the mean hemoglobin value was assessed. The risk of having anemia (hemoglobin level falling below 13 g/dl) was estimated. There were 862 HIV-infected and 1,214 HIV-uninfected men who contributed to the analysis. Hemoglobin values across all 17,341 person-visits, adjusting for age, were generally lower in HIV-infected AIDS-free men with impaired kidney function by -0.22 g/dl (95% CI: -0.42, -0.03) compared to men with either HIV infection or impaired kidney function, but not both. HIV-infected AIDS-free men with impaired kidney function have a higher risk of anemia by 1.2% compared to HIV-uninfected men with normal kidney function. Comorbid conditions and medication use did not explain this increase in risk. HIV infection and impaired kidney function have a combined impact on lowering hemoglobin levels, resulting in a higher risk of anemia.

Disparities in prevalence of key chronic diseases by gender and race/ethnicity among antiretroviral-treated HIV-infected adults in the US

BACKGROUND

Certain sociodemographic subgroups of HIV-infected patients may experience more chronic disease than others due to behavioural risk factors, advanced HIV disease or complications from extended use of combination antiretroviral therapy (cART), but recent comparative data are limited.

METHODS

We studied HIV-infected adult patients in care during 2006-2010 who had been prescribed ≥ 6 months of cART. We analysed the prevalence of selected key chronic conditions and polymorbidity (having 2 or more out of 10 key conditions) by gender and race/ethnicity.

RESULTS

Of the 3,166 HIV-infected patients (median age 47 years, CD4⁺ T-cell count 496 cells/mm³, duration of cART use 6.8 years), 21% were female, 57% were non-Hispanic White and over half were current or former tobacco smokers. The five most frequent conditions among women (median age 45 years) were dyslipidaemia (67.3%), hypertension (57.4%), obesity (31.7%), viral hepatitis B or C coinfection (29.0%) and low high-density lipoprotein cholesterol (HDLc; 27.3%). The five most frequent conditions in men (median age 47 years) were dyslipidaemia (81.2%), hypertension (54.4%), low HDLc (41.1%), elevated triglycerides (32.3%) and elevated non-HDLc (26.8%). In multivariable analyses, Hispanic patients had higher prevalence of obesity and diabetes than White patients; Black patients had higher prevalence of obesity and hypertension but lower rates of lipid abnormalities. Of all patients, 73.7% of women and 66.8% of men had polymorbidity, with no evidence of disparities by race/ethnicity.

CONCLUSIONS

Among contemporary cART-treated HIV-infected adults, chronic conditions and polymorbidity were common, underscoring the importance of chronic disease prevention and management among ageing HIV-infected patients.

Low free testosterone in HIV-infected men is not associated with subclinical cardiovascular disease

OBJECTIVES

Low testosterone (T) is associated with cardiovascular disease (CVD) and increased mortality in the general population; however, the impact of T on subclinical CVD in HIV disease is unknown. This study examined the relationships among free testosterone (FT), subclinical CVD, and HIV disease.

METHODS

This was a cross-sectional analysis in 322 HIV-uninfected and 534 HIV-infected men in the Multicenter AIDS Cohort Study. Main outcomes were coronary artery calcification presence, defined as a coronary artery calcium (CAC) score  >10 (CAC score was the geometric mean of the Agatston scores of two computed tomography replicates), and far wall common carotid intima-media thickness (IMT)/carotid lesion presence by B-mode ultrasound.

RESULTS

Compared with the HIV-uninfected men in our sample, HIV-infected men were younger, with lower body mass index (BMI) and more often Black. HIV-infected men had lower FT (age-adjusted FT 88.7 ng/dL vs. 101.7 ng/dL in HIV-uninfected men; P=0.0004); however, FT was not associated with CAC, log carotid IMT, or the presence of carotid lesions. HIV status was not associated with CAC presence or log carotid IMT, but was associated with carotid lesion presence (adjusted odds ratio 1.69; 95% confidence interval 1.06, 2.71) in HIV-infected men compared with HIV-uninfected men.

CONCLUSIONS

Compared with HIV-uninfected men, HIV-infected men had lower FT, as well as more prevalent carotid lesions. In both groups, FT was not associated with CAC presence, log carotid IMT, or carotid lesion presence, suggesting that FT does not influence subclinical CVD in this population of men with and at risk for HIV infection.

Influence of gender on receipt of guideline-based antiretroviral therapy in the era of HAART

United States HIV guidelines delineate preferred antiretroviral treatment (ART) and discourage use of sub-potent, toxic, or adversely interacting combinations. It is unclear how often patients receive guideline concordant ART and what factors are correlated with receiving guideline-inconsistent ART. The objective of this study was to assess ART reported by participants of the Women's Interagency HIV Study (WIHS) and the Multicenter AIDS Cohort Study (MACS) to determine whether gender is associated with receipt of guideline-inconsistent ART. ART reported by WIHS and MACS participants from 1 January 2001, to 31 December 2007, was assessed for concordance with HIV guidelines. Logistic regression with generalized estimating equations estimated the crude and adjusted odds ratios and 95% confidence intervals associated with guideline-inconsistent regimens. Of 2937 participants, 463 subjects (WIHS n = 263; MACS n = 200) reported guideline-inconsistent ART during the study period. Age > 50 years (aOR = 2.22, 95% CI 1.14, 4.33) and HIV-1 RNA (aOR = 1.17, 95% CI 1.08, 1.25) but not participant gender (aOR = 1.21, 95% CI 0.88, 1.65) were associated with guideline-inconsistent ART. The prevalence of guideline-inconsistent ART peaked in 2004; however, there was not a statistically significant increase or decrease over time. Guideline-inconsistent ART was not related to gender, but was often used by older patients and patients with higher viral loads. Monitoring ART quality based on concordance with expert guidelines could improve treatment outcomes in a substantial number of patients.

Universal GFR determination based on two time points during plasma iohexol disappearance

An optimal measurement of glomerular filtration rate (GFR) should minimize the number of blood draws, and reduce procedural invasiveness and the burden to study personnel and cost, without sacrificing accuracy. Equations have been proposed to calculate GFR from the slow compartment separately for adults and children. To develop a universal equation, we used 1347 GFR measurements from two diverse groups consisting of 527 men in the Multicenter AIDS Cohort Study and 514 children in the Chronic Kidney Disease in Children cohort. Both studies used nearly identical two-compartment (fast and slow) protocols to measure GFR. To estimate the fast component from markers of body size and of the slow component, we used standard linear regression methods with the log-transformed fast area as the dependent variable. The fast area could be accurately estimated from body surface area by a simple parameter (6.4/body surface area) with no residual dependence on the slow area or other markers of body size. Our equation measures only the slow iohexol plasma disappearance curve with as few as two time points and was normalized to 1.73 m2 body surface area. It is of the form: GFR=slowGFR/[1+0.12(slowGFR/100)]. In a random sample utilizing a third of the patients for validation, there was excellent agreement between the calculated and measured GFR with low root mean square errors being 4.6 and 1.5 ml/min per 1.73 m2 for adults and children, respectively. Thus, our proposed simple equation, developed in a combined patient group with a broad range of GFRs, may be applied universally and is independent of the injected amount of iohexol.

Low physical function as a risk factor for incident diabetes mellitus and insulin resistance

Data from 1790 HIV-infected and uninfected men in the Multicenter AIDS Cohort Study (MACS) were analyzed to evaluate relationships between physical function, incident diabetes mellitus (DM) and insulin resistance among HIV-infected and -uninfected men. DM was defined in two ways, using less stringent and more stringent criteria. The 10-item Physical Functioning Scale from the Short Form-36 Health Survey measured baseline physical function. Cumulative DM incidence was highest among HIV-uninfected and HIV-infected men with low physical function. Physical function was a risk factor for DM in HIV-uninfected men and remained so after controlling for BMI, DM family history and race. Among HIV-infected men, physical function was an independent risk factor for DM using the less stringent diabetes definition. This study supports our previous findings that low physical function is an important risk factor for DM in the MACS cohort.

Excess mortality in patients with AIDS in the era of highly active antiretroviral therapy: temporal changes and risk factors

BACKGROUND

Excess mortality has decreased among human immunodeficiency virus (HIV)-infected patients but without evidence of a decrease among patients with AIDS. We assessed temporal changes in excess mortality and elucidated risk factors for excess mortality in patients with AIDS diagnosed in the era of highly active antiretroviral therapy (HAART).

METHODS

We included 1188 patients of the Longitudinal Study of Ocular Complications in AIDS who were aged 25-64 years at enrollment and who received a diagnosis of AIDS after 1995. We calculated excess mortality as the age-, year-, and sex-adjusted difference in mortality rates between patients with AIDS and persons in the US general population during the period 1999-2007. We used a relative survival model to identify risk factors for excess mortality.

RESULTS

There were a mean of 50 excess deaths per 1000 person-years (95% confidence interval [CI], 44-57 excess deaths per 1000 person-years) during 1999-2007. Excess mortality almost halved, with an annual decrease of 8.0% per year (95% CI, 3.0%-12.7%; P = .002) but remained high at 36 excess deaths per 1000 person-years in 2007. Viral load >400 copies/mL (compared with <or= 400 copies/mL; risk ratio, 3.4; 95% CI, 2.3-5.0), CD4(+) count <200 cells/μL (compared with >or= 200 cells/μL; risk ratio, 2.7; 95% CI, 1.9-3.9), and cytomegalovirus retinitis (risk ratio, 1.6; 95% CI, 1.2-2.1) were the strongest risk factors for excess mortality.

CONCLUSIONS

Excess mortality among patients with AIDS was nearly halved in the HAART era and most strongly linked to stage of HIV disease. These results reflect the continuing improvements in AIDS management but also highlight that excess mortality remains ∼5 times higher in patients with AIDS than in HIV-infected patients without AIDS.

Association between abnormal contrast sensitivity and mortality among people with acquired immunodeficiency syndrome

PURPOSE

To investigate the relationship between contrast sensitivity (CS) and mortality among people with acquired immunodeficiency syndrome (AIDS); and to explore the hypothesis that abnormal CS is a marker of systemic, life-threatening microvascular disease.

DESIGN

Longitudinal, observational cohort study.

METHODS

We evaluated 3395 eyes of 1706 individuals enrolled in the Longitudinal Study of the Complications of AIDS (1998-2008). CS was evaluated as a risk factor for death, and was compared to the presence of systemic diseases characterized by microvasculopathy (diabetes, cardiovascular disease, stroke, renal disease) and to laboratory markers of those diseases. Abnormal CS was defined as logCS <1.5 (lower 2.5th percentile for a normal control population).

RESULTS

CS was abnormal in 284 of 1691 (16.8%) study participants at enrollment. There was a positive relationship between the presence of abnormal CS at study entry and mortality (relative risk 2.0, 95% confidence interval 1.7-2.3, P < .0001). Abnormal CS was related to the presence of cardiovascular disease, stroke, and renal disease (all P values

CONCLUSIONS

Abnormal CS among people with AIDS is associated with increased mortality, and is independent of other risk factors for death that are monitored routinely. The relationship may indicate life-threatening microvascular disease in other organs.

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Key Words Collapse

MESH Headings

• Acquired Immunodeficiency Syndrome/mortality
• Adult
• Cardiovascular Diseases/mortality
• Cause of Death
• Contrast Sensitivity
• Female
• Follow-Up Studies
• Humans
• Male
• Perceptual Disorders/mortality
• Prospective Studies
• Risk Factors

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Grants

• ULI RR024996 NCRR NIH HHS
• U01 AI32783 NIAID NIH HHS
• 5M01 RR 05096 NCRR NIH HHS
• M01 RR000865 NCRR NIH HHS
• 5M01 RR00043 NCRR NIH HHS
• U01 AI027660 NIAID NIH HHS
• U10 EY008057 NEI NIH HHS
• U10 EY 08057 NEI NIH HHS
• M01 RR000043 NCRR NIH HHS
• 5M01 RR 00350 NCRR NIH HHS
• U10 EY08052 NEI NIH HHS
• M01 RR000096 NCRR NIH HHS
• M01 RR000046 NCRR NIH HHS
• UL1 RR024996 NCRR NIH HHS
• U01 AI 27660 NIAID NIH HHS
• U01 AI 27674 NIAID NIH HHS
• U01 AI027663 NIAID NIH HHS
• 5M01 RR 00865 NCRR NIH HHS
• U01 AI027670 NIAID NIH HHS
• U01 AI 27670 NIAID NIH HHS
• 5M01 RR00096 NCRR NIH HHS
• 5M01 RR00046 NCRR NIH HHS
• U01 AI25868 NIAID NIH HHS
• U01 AI032783 NIAID NIH HHS
• U01 AI 27663 NIAID NIH HHS
• U01 AI025868 NIAID NIH HHS

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The association of HIV susceptibility testing with survival among HIV-infected patients receiving antiretroviral therapy: a cohort study

BACKGROUND

HIV-1 genotypic and phenotypic susceptibility testing (GPT) optimizes antiretroviral selection, but its effect on survival is unknown.

OBJECTIVE

To evaluate the association between GPT and survival.

DESIGN

Cohort study.

SETTING

10 U.S. HIV clinics.

PATIENTS

2699 HIV-infected patients eligible for GPT (plasma HIV RNA level >1000 copies/mL) seen from 1999 through 2005.

MEASUREMENTS

Demographic characteristics, clinical factors, GPT use, all-cause mortality, and crude and adjusted hazard ratios (HRs) for the association of GPT with survival.

RESULTS

Patients were followed for a median of 3.3 years; 915 (34%) had GPT. Patients who had GPT had lower mortality rates than those who did not (2.0 vs. 2.7 deaths per 100 person-years). In standard Cox models, GPT was associated with improved survival (adjusted HR, 0.69 [95% CI, 0.51 to 0.94]; P = 0.017) after controlling for demographic characteristics, CD4+ cell count, HIV RNA level, and intensity of clinical follow-up. In subgroup analyses, GPT was associated with improved survival for the 2107 highly active antiretroviral therapy (HAART)-experienced patients (2.2 vs. 3.2 deaths per 100 person-years for patients who had GPT vs. those who did not have GPT; adjusted HR, 0.60 [CI, 0.43 to 0.82]; P = 0.002) and for the 921 triple antiretroviral class-experienced patients (2.1 vs. 3.1 deaths per 100 person-years; adjusted HR, 0.61 [CI 0.40 to 0.93]; P = 0.022). Marginal structural models supported associations between GPT and improved survival in the overall cohort (adjusted HR, 0.54; P = 0.001) and in the HAART-experienced group (adjusted HR, 0.56; P = 0.003).

LIMITATIONS

Use of GPT was not randomized. Residual confounding may exist.

CONCLUSION

Use of GPT was independently associated with improved survival among HAART-experienced patients.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Fat distribution and longitudinal anthropometric changes in HIV-infected men with and without clinical evidence of lipodystrophy and HIV-uninfected controls: a substudy of the Multicenter AIDS Cohort Study

BACKGROUND

Fat abnormalities are common among HIV-infected persons, but few studies have compared regional body fat distribution, including visceral fat, in HIV-infected and HIV-uninfected persons and their subsequent trajectories in body composition over time.

METHODS

Between 1999 and 2002, 33 men with clinical evidence of lipodystrophy (LIPO+), 23 HIV-infected men without clinical evidence of lipodytrophy (LIPO-), and 33 HIV-uninfected men were recruited from the four sites of the Multicenter AIDS Cohort Study (MACS). Participants underwent dual-energy x-ray absorptiometry, quantitative computerized tomography of the abdomen and thigh, and circumference measurements of the waist, hip and thigh. Circumference measurements at each semi-annual MACS visit between recruitment and 2008 were used to compare average annual anthropometric changes in the 3 groups.

RESULTS

Body mass index (BMI) was lower in LIPO+ men than in the LIPO- men and the HIV- uninfected controls (BMI: 23.6 +/- 0.4 vs 26.8 +/- 1.5 vs 28.7 +/- 0.9 kg/m(2), respectively, p < 0.001). The average amount of visceral adipose tissue (VAT) was similar in all three groups (p = 0.26), but after adjustment for BMI, VAT was higher in the LIPO+ group (169 +/- 10 cm(2)) compared to the LIPO- men (129 +/- 12 cm(2), p = 0.03) and the HIV-uninfected group (133 +/- 11 cm(2), p = 0.07). Subcutaneous adipose tissue (thigh, abdomen) and total extremity fat were less in the HIV-infected men (LIPO+ and LIPO-) than in the HIV-uninfected men. Over an average of 6 years of follow-up, waist circumference increased at a faster rate in LIPO+ group, compared to the LIPO- men (0.51 cm/year vs 0.08 cm/year, p = 0.02) and HIV-uninfected control men (0.21 cm/year, p = 0.06). The annual changes in hip and thigh circumferences were similar in all three groups

CONCLUSION

Subcutaneous lipoatrophy was observed in HIV-infected patients, even those without clinical evidence of lipodystrophy, compared to age-matched HIV-uninfected men. Despite markedly lower BMI, HIV-infected men with lipodystrophy had a similar amount of VAT as HIV-uninfected men and tended to have more rapid increases in waist circumference over 6 years of follow-up. These longitudinal increases in waist circumference may contribute to the development of cardiovascular risk in HIV-infected patients with lipodystrophy.

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, tolerability, pharmacokinetics, and efficacy of an interleukin-2 agonist among HIV-infected patients receiving highly active antiretroviral therapy

We sought to determine the safety, maximum tolerated dose, optimal dose, and preliminary dose efficacy of intermittent subcutaneously (s.c.) administered BAY 50-4798 among patients with HIV infection receiving highly active antiretroviral therapy (HAART) compared with patients receiving HAART alone. A phase I/II randomized, double-blind, dose-escalation study was conducted of the safety, tolerability, pharmacokinetics, and efficacy of s.c. BAY 50-4798 administered to HIV-infected patients already receiving stable HAART. There were no unexpected safety findings in a population of HIV-infected patients receiving HAART plus SC BAY 50-4798 as adjunctive therapy. BAY 50-4798 exhibited nearly dose-proportional pharmacokinetics, and accumulation was minimal during multiple-dose treatment. Limited efficacy data indicated that treatment with BAY 50-4798 caused at least a transient increase in CD4(+) T cell counts in some recipients, particularly at the early time points. In general, this effect appeared to increase with increasing dose. Bay 50-4798 was generally well tolerated across the dose range tested, but a lack of potent, sustained immunologic activity suggests that further optimization of dose and schedule will be necessary.

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.

Whole-blood interleukin-18 level during early HIV-1 infection is associated with reduced CXCR4 coreceptor expression and interferon- gamma levels

Interleukin (IL)-18 generates T helper 1-type immunity and inhibits human immunodeficiency virus type 1 (HIV-1) in primary cells in vitro. Because IL-18 may participate in HIV-1 containment, whole-blood IL-18 levels were measured in 20 healthy control subjects and longitudinally in 28 subjects with early HIV-1 infection. Compared with those in control subjects, IL-18 levels were higher during early HIV-1 infection, and IL-18 levels predicted reduced CXCR4 HIV-1 coreceptor expression and diminished interferon (IFN)- gamma levels. By contrast, a direct association between IL-18 and IFN- gamma levels was observed in blood stimulated with lipopolysaccharide. During early HIV-1 infection, IL-18 may regulate HIV-1 coreceptor expression and have antiretroviral activity.

Macrolide use and the risk of vascular disease in HIV-infected men in the Multicenter AIDS Cohort Study

Background: There has been increasing concern that HIV-infected individuals may be more at risk for cardiovascular events in the highly-active antiretroviral therapy (HAART) era. This study examined the risk of thromboembolic events in HIV-infected and non-infected individuals and the effect of macrolide prophylaxis on those outcomes. Methods: A subcohort analysis was undertaken using data collected in the Multicenter AIDS Cohort Study to examine the relative risk of vascular events (myocardial infarction, unstable angina and ischaemic stroke). Cox proportional hazard model using age as the time scale with time varying cofactors obtained at each semi-annual visit were used to assess the independent effect of macrolide use. Results: Controlling for other significant effects including race and smoking, HIV-infection was not independently associated with vascular events. Increased risk was observed among those who used HAART (relative hazard 1.09, 95% confidence intervals 1.00–1.19 in multivariate model), antihypertensive treatment (1.81 [1.26–2.60]), lipid-lowering medication (1.65 [1.12–2.42]), and antibiotics (1.72 [1.25–2.36]). The protective association of macrolide use for a vascular event in the HAART era was also significant (0.10 [0.01–0.75]). Conclusions: Traditional risk factors are important in the pathogenesis of vascular events in HIV-infected individuals. Macrolide antibiotics may have a protective effect in the HIV-infected individuals in the HAART era.

Longitudinal anthropometric changes in HIV-infected and HIV-uninfected men

BACKGROUND

Although morphologic abnormalities are common among HIV-infected persons receiving highly active antiretroviral therapy (HAART), longitudinal comparative body shape changes among HAART-treated HIV-infected men versus HIV-seronegative men of similar age remain unclear.

METHODS

Since September 1999, men enrolled in the Multicenter AIDS Cohort Study underwent body mass index (BMI) and circumference measurements of the waist, hip, thigh, and arm at each semiannual visit. Changes in these measurements that occurred between 1999 and 2003 among HIV-infected men were compared with measurements of HIV-seronegative men using linear mixed effects regression models. The HIV-infected men were further stratified by treatment group (no antiretroviral therapy [ART], monotherapy or combination [mono/combo] ART, or HAART). Analyses were adjusted for age, nadir CD4 cell count, and BMI (for circumference measurements).

RESULTS

Over the 4-year observation period, mean BMI increased significantly among the 392 HIV-seronegative men (0.12 kg/m/y; P < 0.001) but did not change in the 3 HIV-infected groups (combined n = 661). Mean waist and hip circumferences increased significantly in all groups. Hip circumferences increased more slowly in the HIV-positive HAART-treated group (n = 488) than in the HIV-seronegative group (0.18 vs. 0.49 cm/y; P < 0.001), however, yielding a more rapid increase in the waist/hip ratio in the HIV-positive, HAART-treated group over time (0.005 per year; P < 0.001).

CONCLUSIONS

The increased rate of change in waist/hip ratio in HIV-infected men receiving HAART compared with HIV-seronegative men is attributable to slower increases in hip circumference rather than an increased rate of change in waist circumference. These findings underscore the importance of body fat composition changes in the peripheral compartment relative to the central compartment among HIV-infected men receiving HAART.

Mortality in the highly active antiretroviral therapy era: changing causes of death and disease in the HIV outpatient study

BACKGROUND

AIDS-related death and disease rates have declined in the highly active antiretroviral therapy (HAART) era and remain low; however, current causes of death in HAART-treated patients remain ill defined.

OBJECTIVE

To describe mortality trends and causes of death among HIV-infected patients in the HAART era.

DESIGN

Prospective, multicenter, observational cohort study of participants in the HIV Outpatient Study who were treated from January 1996 through December 2004.

MEASUREMENTS

Rates of death, opportunistic disease, and other non-AIDS-defining illnesses (NADIs) determined to be primary or secondary causes of death.

RESULTS

Among 6945 HIV-infected patients followed for a median of 39.2 months, death rates fell from 7.0 deaths/100 person-years of observation in 1996 to 1.3 deaths/100 person-years in 2004 (P=0.008 for trend). Deaths that included AIDS-related causes decreased from 3.79/100 person-years in 1996 to 0.32/100 person-years in 2004 (P=0.008). Proportional increases in deaths involving liver disease, bacteremia/sepsis, gastrointestinal disease, non-AIDS malignancies, and renal disease also occurred (P=or<0.001, 0.017, 0.006, <0.001, and 0.037, respectively.) Hepatic disease was the only reported cause of death for which absolute rates increased over time, albeit not significantly, from 0.09/100 person-years in 1996 to 0.16/100 person-years in 2004 (P=0.10). The percentage of deaths due exclusively to NADI rose from 13.1% in 1996 to 42.5% in 2004 (P<0.001 for trend), the most frequent of which were cardiovascular, hepatic, and pulmonary disease, and non-AIDS malignancies in 2004. Mean CD4 cell counts closest to death (n=486 deaths) increased from 59 cells/microL in 1996 to 287 cells/microL in 2004 (P<0.001 for trend). Patients dying of NADI causes were more HAART experienced and initiated HAART at higher CD4 cell counts than those who died with AIDS (34.5% vs 16.8%, respectively, received HAART for 4 of more years, P<0.0001; 22.4% vs 7.8%, respectively, initiated HAART with CD4 cell counts of more than 350 cells/microL, P<0.001).

CONCLUSIONS

Although overall death rates remained low through 2004, the proportion of deaths attributable to non-AIDS diseases increased and prominently included hepatic, cardiovascular, and pulmonary diseases, as well as non-AIDS malignancies. Longer time spent receiving HAART and higher CD4 cell counts at HAART initiation were associated with death from non-AIDS causes. CD4 cell count at time of death increased over time.

C-Reactive Protein Is a Marker for Human Immunodeficiency Virus Disease Progression

BACKGROUND

Limited data on acute-phase C-reactive protein (CRP) levels in human immunodeficiency virus (HIV) infection exist.

METHODS

We obtained a single measurement of CRP from 513 HIV-infected men in the Multicenter AIDS Cohort Study to examine the association between CRP and immune suppression and progression to AIDS. We estimated changes in CRP during the course of HIV infection in 81 of these individuals using specimens collected from October 1, 1984, to December 31, 1996.

RESULTS

The cross-sectional associations between log(10) CRP were correlated inversely with CD4 lymphocyte counts (r=-0.17; P<.001) and directly with log10 HIV RNA levels (r=0.20; P<.001). Levels of CRP of more than 2.3 mg/L were associated with a decreased time to the development of AIDS (relative time to AIDS, 0.36; P<.001) compared with individuals with CRP levels of 1.2 mg/L or less, which remained significant after adjustment for CD4 lymphocyte counts and HIV RNA and hemoglobin concentrations. Levels of CRP significantly increased over time with mean slopes of 8.5% (95% confidence interval, 4.9%-12.2%) and 4.5% (95% confidence interval CI, 2.1%-6.9%) per year for individuals with and without progression to AIDS, respectively. Individuals had a geometric mean CRP level of 2.5 mg/L in the 6-month interval before progression to AIDS, which was an increase from a nadir of 1.0 mg/L at 6.5 years before progression to AIDS.

CONCLUSIONS

Levels of CRP were associated with HIV disease progression independent of CD4 lymphocyte counts and HIV RNA levels. In addition, regardless of progression to AIDS, HIV-infected individuals had a significant increase in CRP over time. This may have implications for cardiovascular disease among HIV-infected individuals.

Transient Viremia in HIV-Infected Patients and Use of Plasma Preparation Tubes

Using plasma preparation tubes for the collection and storage of plasma resulted in factitious, low-level human immunodeficiency virus type 1 (HIV-1) viremia among patients receiving highly active antiretroviral therapy who incurred unnecessary additional clinic visits, laboratory testing, and medication changes. We caution clinicians against the routine use of plasma preparation tubes for collection of blood samples for HIV-1 level 1 quantification.

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

OBJECTIVE

To estimate insulin resistance and its relationship to antiretroviral therapy (ART) in a cohort of HIV-infected persons with comparison to HIV-seronegative controls.

DESIGN

Prospective cohort of 533 HIV-infected and 755 HIV-seronegative men in the Multicenter AIDS Cohort Study evaluated at 6-month intervals between 1999 and 2003.

METHODS

Recent ART exposure was assessed by type of treatment in the preceding 6 months [i.e., no ART, monotherapy, combination ART, or highly active antiretroviral therapy (HAART) with and without a protease inhibitor (PI)]. Cumulative exposure was determined for the three major ART classes and for individual medications within each class. Two endpoints, a modified QUICKI index, 100 x 1/[log10(glucose) + log10(insulin)] and fasting hyperinsulinemia (insulin > 15 microU/ml), were assessed. All statistical models were adjusted for age, body mass index, race, nadir CD4 cell count, hepatitis C serostatus and family history of diabetes mellitus.

RESULTS

Each of the HIV-infected groups had higher odds of hyperinsulinemia and lower mean QUICKI than the HIV-seronegative men. Each additional year of exposure to nucleoside analogue reverse transcriptase inhibitors (NRTI) was associated with increased odds of hyperinsulinemia [odds ratio (OR), 1.08; 95% confidence interval (CI), 1.02-1.13) and a lower QUICKI (-0.04; 95% CI, -0.07 to -0.01). Cumulative exposure to non-nucleoside analogue reverse transcriptase inhibitors or PI drugs was not associated with either insulin resistance marker. Of individual medications examined, stavudine was associated with the highest risk of hyperinsulinemia (OR, 1.2; 95% CI, 1.2-1.3).

CONCLUSIONS

Fasting surrogate markers suggest increased insulin resistance in HIV-infected men, which is related to cumulative NRTI exposure.

Antiretroviral Therapy and the Prevalence and Incidence of Diabetes Mellitus in the Multicenter AIDS Cohort Study

BACKGROUND

The risk of diabetes mellitus (DM) in human immunodeficiency virus (HIV)-infected patients receiving highly active antiretroviral therapy (HAART) has not been well defined.

METHODS

We conducted an analysis in the Multicenter AIDS Cohort Study to determine the prevalence and incidence of DM in this cohort of HIV-infected and HIV-seronegative men. Prevalence analysis included 1278 men (710 HIV seronegative and 568 HIV infected, 411 receiving HAART) with fasting glucose concentration determinations at baseline. Incidence analysis included 680 of these 1278 men who at the baseline visit had a fasting glucose concentration of 98 mg/dL (5.4 mmol/L) or less, no self-reported history of DM, and no self-reported use of antidiabetic medication. Diabetes mellitus was defined as a fasting glucose concentration of 126 mg/dL (7 mmol/L) or higher, self-reported diagnosis of DM, or self-reported use of antidiabetic medication.

RESULTS

Fifty-seven (14%) of the 411 HIV-infected men using HAART at the baseline visit had prevalent DM compared with 33 (5%) of the 711 HIV-seronegative men (prevalence ratio = 4.6; 95% confidence interval, 3.0-7.1, adjusted for age and body mass index [calculated as weight in kilograms divided by the square of height in meters]). The rate of incident DM was 4.7 cases per 100 person-years among HIV-infected men using HAART compared with 1.4 cases per 100 person-years among HIV-seronegative men (rate ratio = 4.11; 95% confidence interval, 1.85-9.16, adjusted for age and body mass index), during the 4-year observation period, based on a median follow-up of 2.3 years.

CONCLUSION

The incidence of DM in HIV-infected men with HAART exposure was greater than 4 times that of HIV-seronegative men, representing a risk that is higher than previous estimates.