Interleukin 6 Is a Stronger Predictor of Clinical Events Than High-Sensitivity C-Reactive Protein or D-Dimer During HIV Infection.

BACKGROUND: Interleukin 6 (IL-6), high-sensitivity C-reactive protein (hsCRP), and D-dimer levels are linked to adverse outcomes in human immunodeficiency virus (HIV) infection, but the strength of their associations with different clinical end points warrants investigation. METHODS: Participants receiving standard of care in 2 HIV trials with measured biomarker levels were followed to ascertain all-cause death, non-AIDS-related death, AIDS, cardiovascular disease (CVD), and non-AIDS-defining malignancies. Hazard ratios (HRs) and 95% confidence intervals (CIs) of each end point for quartiles and log2-transformed IL-6, hsCRP, and D-dimer levels were calculated using Cox models. Marginal models modelling multiple events tested for equal effects of biomarker levels on different end points. RESULTS: Among 4304 participants, there were 157 all-cause deaths, 117 non-AIDS-related deaths, 101 AIDS cases, 121 CVD cases, and 99 non-AIDS-defining malignancies. IL-6 was more strongly associated with most end points, compared with hsCRP. IL-6 appeared to be a stronger predictor than D-dimer for CVD and non-AIDS-defining malignancies, but 95% CIs overlapped. Independent associations of IL-6 were stronger for non-AIDS-related death (HR, 1.71; 95% CI, 1.43-2.04) and all-cause death (HR, 1.56; 95% CI, 1.33-1.84) and similar for CVD (HR, 1.35; 95% CI, 1.12-1.62) and non-AIDS-defining malignancies (HR, 1.30; 95% CI, 1.06-1.61). There was heterogeneity of IL-6 (P < .001) but not hsCRP (P = .15) or D-dimer (P = .20) as a predictor for different end points. CONCLUSIONS: IL-6 is a stronger predictor of fatal events than of CVD and non-AIDS-defining malignancies. Adjuvant antiinflammatory and antithrombotic therapies should be tested in HIV-infected individuals.

Factors Associated With Plasma IL-6 Levels During HIV Infection.

BACKGROUND: Elevated interleukin 6 (IL-6) levels have been linked to cardiovascular disease, cancer and death. Persons with human immunodeficiency virus (HIV) infection receiving treatment have higher IL-6 levels, but few data are available on factors associated with circulating IL-6. METHODS: Participants in 3 trials with IL-6 measured at baseline were included (N = 9864). Factors associated with IL-6 were identified by linear regression. Demographic and HIV variables (nadir/entry CD4(+) cell count, HIV RNA level, antiretroviral therapy regimen) were investigated in all 3 trials. In the SMART (Strategies for Management of Anti-Retroviral Therapy) trial, CD4/CD8 ratio, smoking, comorbid conditions, serum lipids, renal function (estimated glomerular filtration rate [eGFR]), and educational level were assessed. RESULTS: Demographics associated with higher IL-6 levels were older age and lower education, whereas black race was associated with lower IL-6. Higher HIV RNA levels were associated with higher IL-6 levels, and higher nadir CD4(+) cell counts with lower IL-6 levels. Compared with efavirenz, protease inhibitors were associated with higher and nevirapine with lower IL-6 levels. Smoking and all comorbid conditions were related to higher IL-6. IL-6 levels increased with decreasing eGFR and decreasing serum lipids. CONCLUSIONS: Higher levels of IL-6 were associated with older age, nonblack race, higher body mass index, lower serum lipid levels, HIV replication, low nadir CD4(+) cell count, protease inhibitor use, comorbid conditions, and decreased eGFR. Multiple factors affect inflammation in HIV and should be considered in studies of IL-6 as a biomarker of clinical outcomes.

Determinants of IL-6 levels during HIV infection.

INTRODUCTION: Elevated IL-6 levels have been linked to increased risk of cardiovascular disease (CVD), cancer and death. Compared to the general population, treated HIV+ persons have 50-100% higher IL-6 levels, but few data on the determinants of IL-6 levels during HIV infection currently exist. MATERIAL AND METHODS: Participants in three international HIV trials (SMART, ESPRIT and SILCAAT) with IL-6 plasma levels measured at baseline were included (N=9864). Factors independently associated with log2-transformed IL-6 level were identified by multivariate linear regression; exponentiated estimates corresponding to fold differences (FDs) in IL-6 were calculated. Demographics (age, gender, race, BMI) and HIV-specific variables (nadir and entry CD4 counts, HIV-RNA, use of different ART regimens) were investigated in all three trials. In SMART (N=4498), smoking, comorbidities (CVD, diabetes, hepatitis B/C [HBV/HCV]), HDL-cholesterol, renal function (eGFR) and educational level were also assessed. RESULTS: Demographics associated with higher IL-6 were older age (FD [95% CI]: 1.09 [1.08-1.11] per 10 yr) and higher BMI (1.02 [1.01-1.04] per 5 kg/m(2)), whereas black race was associated with reduced IL-6 (0.96 [0.93-0.99]). As for HIV variables, patients not receiving ART (1.36 [1.29-1.43]) and with higher HIV-RNA (1.24 [1.01-1.52] for >100,000 vs. ≤500 copies/mL) had increased IL-6. Participants taking protease inhibitors (PI) had higher IL-6 (1.14[1.09-1.19]). Higher nadir CD4 count (0.98 [0.97-0.99]/100 cells/µL) was related to lower IL-6. All evaluated comorbidities were related to higher IL-6; FDs in IL-6 were 1.08 [1.04-1.12] for smoking, 1.12 [1.02-1.24] for CVD, 1.07 [1.00-1.16] for diabetes and 1.12 [1.02-1.24] for HBV (1.15 [1.02-1.30]) and 1.53 [1.45-1.62] for HCV. IL-6 increased with decreasing eGFR (0.98 [0.97-1.00]/10 mL/min) and HDL-cholesterol (0.98 [0.96-0.99]/10 mg/mL). Lower education was related to higher IL-6 (1.09 [1.03-1.15] for high school vs. bachelor's degree). CONCLUSIONS: Higher IL-6 levels were associated with older age and non-black race, higher BMI and lower HDL-cholesterol, ongoing HIV replication, low nadir CD4 counts, comorbidities and decreased renal function. This suggests that there are multiple causes of inflammation in treated HIV infection. A possible contribution from PI use was also observed. Contribution from inflammation to explain variation in clinical outcomes for these factors should be investigated.

Factors associated with D-dimer levels in HIV-infected individuals.

BACKGROUND: Higher plasma D-dimer levels are strong predictors of mortality in HIV+ individuals. The factors associated with D-dimer levels during HIV infection, however, remain poorly understood. METHODS: In this cross-sectional study, participants in three randomized controlled trials with measured D-dimer levels were included (N = 9,848). Factors associated with D-dimer were identified by linear regression. Covariates investigated were: age, gender, race, body mass index, nadir and baseline CD4+ count, plasma HIV RNA levels, markers of inflammation (C-reactive protein [CRP], interleukin-6 [IL-6]), antiretroviral therapy (ART) use, ART regimens, co-morbidities (hepatitis B/C, diabetes mellitus, prior cardiovascular disease), smoking, renal function (estimated glomerular filtration rate [eGFR] and cystatin C) and cholesterol. RESULTS: Women from all age groups had higher D-dimer levels than men, though a steeper increase of D-dimer with age occurred in men. Hepatitis B/C co-infection was the only co-morbidity associated with higher D-dimer levels. In this subgroup, the degree of hepatic fibrosis, as demonstrated by higher hyaluronic acid levels, but not viral load of hepatitis viruses, was positively correlated with D-dimer. Other factors independently associated with higher D-dimer levels were black race, higher plasma HIV RNA levels, being off ART at baseline, and increased levels of CRP, IL-6 and cystatin C. In contrast, higher baseline CD4+ counts and higher high-density lipoprotein cholesterol were negatively correlated with D-dimer levels. CONCLUSIONS: D-dimer levels increase with age in HIV+ men, but are already elevated in women at an early age due to reasons other than a higher burden of concomitant diseases. In hepatitis B/C co-infected individuals, hepatic fibrosis, but not hepatitis viral load, was associated with higher D-dimer levels.

Failure to achieve a CD4+ cell count response on combination antiretroviral therapy despite consistent viral load suppression.

OBJECTIVE: To assess CD4 cell count recovery in people severely immunosuppressed at start of antiretroviral therapy (ART) who achieve and maintain viral load suppression. METHODS: Eligible participants from the UK Collaborative HIV Cohort Study started ART with at least three drugs after 1 January 2000. Participants were required to have pre-ART CD4 cell count below 100 cells/µl, at least 2 years of follow-up on ART, have achieved viral load suppression (≤ 50 copies/ml) by 9 months after starting ART and to have maintained this throughout follow-up. Participants were further required to be regularly engaged with care. We calculated the proportion of people who failed to achieve a CD4 cell count of more than 100, 150, 200, 350 and 500 cells/µl by the time of the last follow-up, or 5 years from start of ART, whichever occurred first (censoring date). RESULTS: Of the 400 participants [median (interquartile range) pre-ART CD4 cell count of 38 (14-65) cells/µl], 2 (0.5%), 8 (2%), 28 (7%), 131 (33%) and 259 (65%) failed to achieve a CD4 cell count of more than 100, 150, 200, 350 and 500 cells/µl, by the censoring date, respectively. Kaplan-Meier estimates of the proportion of people reaching each CD4 cell count threshold after 1 year on ART were 88, 70, 50, 14 and 3%, respectively, and after 3 years on ART, 98, 95, 90, 59 and 25%, respectively. Median (interquartile range) follow-up on ART was 3.9 (2.7-4.8) years. CONCLUSION: Given a person with pre-ART CD4 cell count below 100 cells/µl survives and maintains consistent viral load suppression on ART, there is over a 90% chance of reaching a CD4 cell count above 200 cells/µl by 3 years.

Factors associated with adherence amongst 5295 people receiving antiretroviral therapy as part of an international trial.

BACKGROUND: We assessed factors associated with antiretroviral therapy (ART) adherence, including specific ART medications. METHODS: The Strategies for Management of Antiretroviral Therapy study was an international antiretroviral therapy (ART) strategy trial that compared intermittent ART, using CD4(+) T-cell count as a guide, to continuous ART. Adherence during the 7 days before each visit was measured using self-report. We defined high adherence as self-report of taking "all" pills for each prescribed ART medication; all other reports were defined as suboptimal adherence. Factors associated with adherence were assessed using logistic regression with generalized estimating equations. RESULTS: Participants reported suboptimal adherence at 6016 of 35 695 study visits (17%). Factors independently associated with suboptimal adherence were black race, protease inhibitor-containing regimens, greater pill burden, higher maximum number of doses per day, and smoking. Factors independently associated with higher adherence were older age, higher education, region of residence, episodic treatment, higher latest (at the time of adherence) CD4(+) T-cell count, and being prescribed concomitant drugs (ie, medications for comorbidities). Of specific drugs investigated, atazanavir, atazanavir/ritonavir, fosamprenavir, indinavir, indinavir/ritonavir, and lopinavir/ritonavir were associated with suboptimal adherence, and tenofovir disoproxil fumarate/emtricitabine was associated with higher adherence. CONCLUSIONS: In this, the largest analysis of ART adherence to date, some protease inhibitor-containing regimens and regimens with >1 dose per day were associated with suboptimal adherence.