Incident hypertension among adults on ART in Malawi: a nested cohort study

Introduction: As populations on antiretroviral therapy (ART) in sub-Saharan Africa are aging, hypertension has become an increasingly important comorbidity among people living with HIV (PLHIV). To address a paucity of data from sub-Saharan Africa on the incidence of hypertension among PLHIV, we conducted a cohort study in Malawi to assess the frequency and correlates of incident hypertension among PLHIV established on ART. 

Methods: In this prospective cohort study nested in a clinical trial, we followed participants without prevalent hypertension at enrolment and routinely screened their blood pressure (BP). In the parent study, clinically stable adult (≥ 18 years) PLHIV on ART with HIV-RNA ≤ 400 copies/mL and CD4 count ≥ 250/mm3 were randomized to daily trimethoprim-sulfamethoxazole (TS), weekly chloroquine (CQ), or no prophylaxis. We defined hypertension as systolic BP of ≥ 140 mmHg and diastolic BP ≥ 90 mmHg obtained on two consecutive clinic visits. Poisson regression analysis was used to determine the incidence of hypertension, using univariate and multivariate analyses designed based on a Directed Acyclic Graph to identify key predictors of hypertension. 

Results: 1,240 PLHIV (76.4% female, median age 37 years, median duration on ART 3 years, 92.2% on efavirenz-based regimens) were followed from December 2012 to July 2018, accumulating 3,676 person-years of observation (PYO). The incidence of hypertension was 36.9 per 1,000 PYO (95% confidence interval [CI]: 31.0, 43.8), with 40% of diagnoses made before the age of 40 years and the highest incidence observed in the first calendar year of the study. Higher age (incidence rate ratio [IRR] = 1.05, 95%-CI 1.03, 1.07), male sex (IRR = 1,49, 95%-CI 1, 02–2,15; p = 0.029), being overweight (aIRR = 2.55, 95%-CI: 1.27, 5.47) and obese (aIRR = 5.08, 95%-CI; 2.12, 12.18) and being on a non-efavirenz-based ART regimen (aIRR = 2.25, 95%-CI: 1.37, 3.53) were predictors of incident hypertension. Receiving TS (aIRR = 0.42, 95%-CI 0.26, 0.65) compared to receiving no prophylaxis reduced risk of incident hypertension. 

Conclusions: The incidence of hypertension among PLHIV who were stable on longer-term ART was high, justifying routine BP screening at ART clinics. Identified predictors may help targeting screening. A newly observed protective effect of TS prophylaxis on incident hypertension needs confirmation.