Traditional cardiovascular risk factors predicted incident hypertension in a sub-Saharan Africa study, but no association was observed with immunological or antiretroviral treatment status.
Many countries in sub-Saharan Africa are facing an unprecedented epidemic of both infectious and non-communicable diseases. This ‘double burden of disease’ represents a major strain on already under-resourced health systems. Hypertension, in particular, is an independent, reversible risk factor for cardiovascular, cerebrovascular and renal disease, affecting mortality. Yet, the disease remains largely undiagnosed and undertreated in sub-Saharan Africa.
The research conducted by Swiss Tropical and Public Health Institute (Swiss TPH) is among the first longitudinal studies looking at the development of hypertension among people living with HIV in sub-Saharan Africa. In a cohort of 955 HIV-infected people, 111 (11.6%) were hypertensive at the time of HIV diagnosis. An additional 80 people (9.6%) developed hypertension after starting antiretroviral therapy (ART) against HIV. The incidence of hypertension found in this study after ART initiation is more than 1.5 times higher than the one observed in a large multinational study of Europe, the US and Australia.
The study found that development of hypertension was not linked to the level of immunosuppression or any ART regimen in particular, but rather predicted by traditional cardiovascular risk factors such as age, body mass index and renal function. The effect of ART on body mass and the restoration of immunity are potential drivers of hypertension when under treatment.
The study cohort included non-pregnant patients, aged 15 years and above, with a median age of 38 years, who had not been exposed to ART before the study.
Hypertension and other non-communicable diseases share a number of similarities with HIV, such as the chronic evolution of disease and the need for regular follow-up and optimal treatment adherence. The study therefore suggests integrating routine hypertension screening in HIV clinics.
“We have seen that such routine screening is a feasible and effective strategy to diagnose hypertension within an HIV programme,” said Dr Emilio Letang, Swiss TPH and Barcelona Institute for Global Health (ISGlobal). “Moving forward, however, we need to make sure that leveraging such synergies does not compromise the efficiency of existing HIV programmes.”
The study also urges expansion of access to anti-hypertensive medicines. “In many countries across sub-Saharan Africa, there is still a lack of access to drugs against major non-communicable diseases,” said Professor Christoph Hatz, CMO at Swiss TPH. “In order for such integrated care programmes to work successfully, ensuring better availability and affordability of drugs as well as implementing comprehensive preventive and curative measures will be key.”
Introduction: Scarce data are available on the epidemiology of hypertension among HIV patients in rural sub-Saharan Africa. We explored the prevalence, incidence and risk factors for incident hypertension among patients who were enrolled in a rural HIV cohort in Tanzania.
Methods: Prospective longitudinal study including HIV patients enrolled in the Kilombero and Ulanga Antiretroviral Cohort between 2013 and 2015. Non-ART naïve subjects at baseline and pregnant women during follow-up were excluded from the analysis. Incident hypertension was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg on two consecutive visits. Cox proportional hazards models were used to assess the association of baseline characteristics and incident hypertension.
Results: Among 955 ART-naïve, eligible subjects, 111 (11.6%) were hypertensive at recruitment. Ten women were excluded due to pregnancy. The remaining 834 individuals contributed 7967 person-months to follow-up (median 231 days, IQR 119–421) and 80 (9.6%) of them developed hypertension during a median follow-up of 144 days from time of enrolment into the cohort [incidence rate 120.0 cases/1000 person-years, 95% confidence interval (CI) 97.2–150.0]. ART was started in 630 (75.5%) patients, with a median follow-up on ART of 7 months (IQR 4–14). Cox regression models identified age [adjusted hazard ratio (aHR) 1.34 per 10 years increase, 95% CI 1.07–1.68, p = 0.010], body mass index (aHR per 5 kg/m2 1.45, 95% CI 1.07–1.99, p = 0.018) and estimated glomerular filtration rate (aHR < 60 versus ≥ 60 ml/min/1.73 m2 3.79, 95% CI 1.60–8.99, p = 0.003) as independent risk factors for hypertension development.
Conclusions: The prevalence and incidence of hypertension were high in our cohort. Traditional cardiovascular risk factors predicted incident hypertension, but no association was observed with immunological or ART status. These data support the implementation of routine hypertension screening and integrated management into HIV programmes in rural sub-Saharan Africa.
Eduardo Rodríguez-Arbolí, Kim Mwamelo, Aneth Vedastus Kalinjuma, Hansjakob Furrer, Christoph Hatz, Marcel Tanner, Manuel Battegay, Emilio Letang