Abstract P172: Association of Interleukin 6 With Hypertension in HIV Positive Participants in the Strategic Timing of Antiretroviral Treatment (START) Trial

Abstract

Introduction: The association between hypertension (HTN) and inflammation [e.g., estimated via interleukin 6 (IL-6)] in HIV positive persons who have a CD4+ count greater than 500 cells/mm 3 has not been well established. Methods: We studied HTN in the START trial, a randomized study of immediate vs. deferred antiretroviral therapy (ART) in HIV-positive adults who were ART naïve and had a CD4+ count greater than 500 cells/mm 3 . Our analysis included 4249 of the 4,684 HIV positive persons enrolled in START who had no history of cardiovascular disease and had IL-6 measured at baseline. HTN (prevalence at baseline or incidence) was defined as having a systolic BP ≥140 mm Hg, or a diastolic BP ≥90 mm Hg, or use of BP-lowering therapy. Logistic regression and discrete Cox proportional hazard models were used to test the association between IL-6 and HTN prevalence and incidence. Sensitivity analysis were used to test the association between systolic and diastolic BP and IL-6 levels. Results: HTN was prevalent in 18.9% of the cohort at entry. The median age of participants was 36 years, 27% were female, median CD4 + cell count at entry was 651 cells/mm 3 and median HIV RNA level was 13090 copies/mL. In univariate analysis, HTN was significantly associated with higher IL-6 levels at baseline [OR per doubling of IL-6:1.28, 95%CI (1.18, 1.39)]. This association was attenuated and no longer significant after adjusting for race, age, gender, BMI, diabetes, smoking, RNA and CD4+ levels [OR per doubling of IL-6:1.10, 95%CI (0.99, 1.20)]. The reduced OR was primarily due BMI and age, both which were strongly related to HTN. Overall incidence of HTN was 6.9 cases per 100 person year. Baseline IL-6 was not associated with risk of incident HTN in the crude and fully adjusted model [HR per doubling of IL-6:0.98, 95%CI (0.90, 1.10) in adjusted analysis]. This association did not differ by treatment group (p for interaction=0.21). Risk factors such as age, black race, BMI, and male gender were associated with incident HTN. Continuous systolic and diastolic BP were not significantly associated with IL-6 at baseline or in follow-up analyses. Conclusions: IL-6 was not associated with HTN in HIV positive participants with CD4+ counts greater than 500 cells/mm 3 after adjusting for factors known to be associated with HTN and inflammation. Furthermore, baseline IL-6 level was not associated with incident HTN, nor with continuous BP measures. Rather, HTN development was associated with traditional risk factors such as age, race, gender and BMI.