Prevalence of hypertension among antiretroviral therapy naïve patients in Lagos, Nigeria

The Nigerian Institute of Medical Research (NIMR) is the foremost clinical research institute in Nigeria with a mandate to conduct research into diseases of public health importance. As part of her responsibilities, the Clinical Sciences Department within the institute conducts research in areas of communicable and non-communicable diseases in line with priorities and current health challenges. The Clinical Sciences Department operates an HIV clinic that has been in existence since 2002. The clinic was instituted as a research-based clinic to evaluate the effectiveness of generic ART in the country. This was commissioned under the auspices of the US President’s Emergency Plan for AIDS Relief (PEPFAR) program. The clinic has cumulatively enrolled more than 25 000 PLWH and caters to adults, pregnant women, and children infected with HIV. The clinic is in the economic capital of Nigeria, Lagos State providing care and services to a diverse population of citizens and foreign nationals based on the country’s National guidelines for HIV prevention, treatment, and care [27].

Care, treatment and management in the clinic is provided free of charge with support from the Nigerian government, PEPFAR and other multilateral agencies. Prior to enrollment, PLWH are offered counselling services (before and after conformation of HIV diagnosis) to provide reassurance and comfort as well as offer hope towards living positively with the HIV disease. In addition, information is also provided with respect to the ARVs (dosage, adherence, side effects and food -drug interactions).

Patient data relating to the clinical, therapeutic, and laboratory parameters are captured in an electronic database and maintained on a server onsite. Each patient is assigned a unique identification number, which is used to collate the clinic data. All patients enrolled in the clinic are offered a consent form to document their preference regarding the use of their biological samples and clinical data for research. Their responses do not affect their right to care and treatment in the clinic. The facility offers outpatient services only and patients requiring hospital admission are referred to facilities closest to their residence.

This is a cross sectional study, reviewing data collected among ART-naïve PLWH enrolled in the ART clinic over 10 years (January 1, 2010 to December 31, 2019). Participants at enrollment into the clinic who were younger than 18 years, pregnant, or receiving care at a referral centre before transfer to the clinic were excluded. Paediatric participants upon attaining the age of 18 years, and those accessing care for post-exposure prophylaxis were also excluded from the study. All other participants enrolled in the clinic were included in the study analysis.

At enrollment, medical record officers collected sociodemographic information from prospective patients after counselling. The nurse thereafter evaluated specific clinical parameters (temperature, weight, height, blood pressure, and respiratory rate) of the patients. Weight was taken to the nearest 0.1 kg with the patient standing erect and barefoot on the weighing scale (Seca, GmBH). Height was measured in a similar posture with the marker placed on the crown of the head and readings taken to the nearest 0.1 cm (cm).

Blood pressure (BP) measurement was obtained with participants in a sitting position (for 5 min before the procedure) using a digital BP monitor, Omron M2 Eco model (HEM-7120-AF model, Omron Healthcare Co Ltd, Kyoto, Japan) with appropriate cuff size. The clinic adopted the use of the digital BP monitor as the standard equipment for BP readings in February 2014. Before the adoption of digital BP monitors, the manual sphygmomanometer was the standard equipment for BP measurement. Three BP readings were obtained at a sitting, and the average of the three readings was recorded as the participant's BP reading for the clinic consultation.

Clinical history was obtained, and physical examinations were conducted by the clinician. The WHO clinical staging for HIV infection [28] was assessed at the baseline clinic visit. Laboratory investigations include full blood count, cluster of differentiation 4 (CD4) count, viral load, serum urea and creatinine, random blood glucose, hepatitis B and C screening, and serum alanine aminotransferase.

Data collected for this study included the participants’ sociodemographic characteristics (age, sex, educational level, occupational and marital status), cardiovascular risk factors (body mass index [BMI], alcohol consumption), concurrent co-morbidities at enrollment (diabetes mellitus, hypertension, renal disease, tuberculosis), and HIV related factors (WHO clinical staging, viral load, CD4 counts). This was done to determine potential associations with (prevalent) hypertension at enrollment.

The study outcome of interest was prevalent hypertension among ART-naïve PLWH at enrollment. Hypertension was defined as systolic and/or diastolic blood pressure (SBP and DBP) greater than or equal to 140 mmHg and 90 mmHg, respectively [29]. In addition, prior history of hypertension diagnosis or use of anti-hypertensive medications, irrespective of current BP readings was defined as having hypertension [29]. The crude prevalence of hypertension was deduced by dividing the total number of PLWH with hypertension by the total study population, expressing the result in percentages. Similar methodology was applied to deduce annual prevalence of hypertension for the study, specific age groups and gender. The educational level attained by study participants was classified as none, primary, secondary, and tertiary. The first six years of formal education is termed primary, followed by another six years termed secondary (Junior Secondary School 1 – 3 and Senior Secondary School 1 -3), and finally tertiary (colleges of education, polytechnics, and university) levels of education [30]. Alcohol intake per week was categorized as nil, light ( 1–3 units), moderate (4—13 units), and heavy (≥ 14 units) [31]. Study participants were deemed to have co-morbid diabetes mellitus or renal disease if they provided a prior diagnosis (from clinical history or medical records) or were currently on treatment for the co-morbidity. Tuberculosis was deduced following both clinical history and physical examination [32, 33]. BMI was calculated as the weight (in kilogram) divided by height squared (in metres squared) – Kg/m². BMI was classified as underweight (< 18.5), normal (18.5 – 24.9), overweight (25.0 -29.9), and obese (≥ 30.0) [34]. Viral suppression was defined as a viral load below 1000 copies per millimeter [35] and CD4 counts were classified per CDC Staging [36, 37].

Data are presented as counts and percentages for categorical variables, while mean and standard deviations or median and 25th—75th percentiles were used for continuous variables. The crude prevalence of hypertension was determined from the blood pressure readings in the study while age and sex standardised prevalence was computed using the Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS) 2018 report [19]. The NAIIS 2018 report is the latest version of the household survey of HIV infection in the country and direct standardization method was employed to determine the age and sex standardised prevalence in our study. Logistic regression analysis (odds ratio and 95% Confidence Intervals) was used to determine the associations with hypertension. Variables found to be statistically significant in univariate analysis (p-value < 0.05) were included in the regression analysis for the multivariable regression models (enter and backward elimination methods). The backward elimination method was used select significant variables in the final multivariable model based with the Akaike information criterion (AIC) determined for the selected model. Statistical significance was set at a p-value of < 0.05. Data were analysed using Statistical Package for Social Sciences (SPSS) version 26 (IBM SPSS Inc, Chicago, IL).

To our knowledge, this study represents the largest cohort of PLWH for which the prevalence of hypertension has been determined in West Africa. In addition, this study is among the first to determine the age- and sex-standardised prevalence rates for hypertension among PLWH in Nigeria which enables appropriate comparisons with other studies. The different instruments used to measure blood pressure pre- and post-February 2014, i.e., manual sphygmomanometer vs. digital BP monitors could have affected readings. Tobacco use, physical activity, lipid profiles, and dietary consumption were not captured in our analysis as these variables were not collected during clinic consultations. These variables may have provided insight into associated factors for hypertension in the cohort.

While the study sample originated from a single clinic, it is likely representative of the population of PLWH in the Lagos state during the study period. The NIMR HIV clinic has been in operation since 2002, providing care to PLWH from across Lagos state and beyond. Subsidies from the PEPFAR program allowed the care to be free to the end-users, therefore removing financial barriers that could lead to differential enrollment of wealthy people in the clinic.