Association between HIV and treatment-resistant hypertension in Malawian adults: a protocol for a case–control study

INTRODUCTION: Treatment-resistant hypertension (RH), defined as uncontrolled blood pressure (≥140/90 mm Hg) despite treatment with ≥3 medications of different classes (including diuretics) at optimal doses, is associated with poor prognosis and an elevated risk of end-organ damage. In areas where HIV is endemic, such as sub-Saharan Africa, the risk of hypertension is high in people living with HIV. It remains unknown if HIV infection further increases the risk of RH. This study seeks to determine the association between HIV and RH as well as investigate other factors associated with RH in hypertensive Malawian adults. METHODS AND ANALYSIS: A case–control study will be conducted among adult hypertensive patients attending a clinic at a referral hospital in Malawi. The cases will be hypertensive patients with a confirmed diagnosis of RH. For each case, two controls (hypertensive patients without RH), frequency matched for age group and sex, will be selected from among hospital clients attending the same hypertension clinic as the case. In both groups, HIV status will be ascertained. Additionally, information on other potential risk factors of RH, such as chronic kidney disease, obesity, hypercholesteraemia, diabetes, smoking, alcohol use, antiretroviral therapy regimen and duration, will be collected in both cases and controls. For each of the potential risk factors, ORs will be calculated to quantify the strength of their association with RH. In a multivariate analysis, conditional logistic regression will be used to assess the independent association between HIV and RH as well as the influence of the other potential drivers of RH. ETHICS AND DISSEMINATION: This protocol has been approved by the College of Medicine Research Ethics Committee (COMREC) in Malawi (P.05/22/3637). Findings from this study will be disseminated through a peer-reviewed publication in an open-access international journal. Furthermore, anonymised data will be available on request from the authors.