Community health worker-led home blood pressure monitoring in rural sub-Saharan Africa: a diagnostic accuracy study

BACKGROUND: Home blood pressure monitoring (HBPM) coordinated by community health workers (CHWs) is a potential strategy to improve hypertension detection in sub-Saharan Africa, yet data on its diagnostic performance in this setting are scarce. We aimed to determine the diagnostic accuracy of CHW-coordinated HBPM in Kenya and The Gambia using daytime ambulatory blood pressure monitoring (ABPM) as the reference standard. METHODS: In this cross-sectional diagnostic accuracy study, we recruited a random sample of representative age-stratified individuals aged 30 years or older from the general population of two health and demographic surveillance systems in Kilifi, Kenya, and Kiang West, The Gambia. We used the latest enumeration lists of the two health and demographic surveillance systems as sampling frames and performed computer-generated random sampling within five predefined age strata (30-39 years, 40-49 years, 50-59 years, 60-69 years, and ≥70 years). Pregnant women were excluded, and participants were eligible to participate irrespective of previous hypertension status. CHWs trained and provided participants with HBPM devices for self-measurement of blood pressure twice a day, for a minimum of 3 days and a maximum of 7 days. For the reference standard measurement, an ABPM device was fitted by CHWs, and ambulatory blood pressure was measured every 15 min during the day and 30 min at night. We used blood pressure cutoffs derived from the European Society of Hypertension to determine the age-standardised measures of accuracy (sensitivities, specificities, positive predictive values [PPVs] and negative predictive values [NPVs], positive likelihood ratios [LR+] and negative likelihood ratios [LR-] and area under receiver operating characteristic curves) of HBPM among participants who had valid HBPM and ABPM measurements. FINDINGS: Between Aug 18, 2023, and Dec 13, 2024, from 1452 eligible participants, we included 1279 participants with valid HBPM and ABPM measurements (696 in Kenya and 583 in The Gambia). In 1279 participants, the median age was 54 years (IQR 43-66), 805 (62·9%) were women, and 474 (37·1%) were men. The age-standardised prevalence of hypertension on daytime ABPM was 23·1% (95% CI 19·9-26·2) in Kenya and 27·1% (23·6-30·6) in The Gambia while the respective prevalences on HBPM were 32·5% (29·1-35·8) and 31·2% (27·5-34·9). The age-standardised sensitivities and specificities of HBPM were 82·6% (76·2-89·0) and 82·4% (79·0-85·7) in Kenya and 68·7% (61·3-76·1) and 83·5% (79·7-87·2) in The Gambia. The age-standardised PPVs and NPVs were 58·6% (52·0-65·2) and 94·0% (91·6-96·4) in Kenya and 59·9% (52·5-67·2) and 88·1% (84·8-91·4) in The Gambia, respectively. The age-standardised LR+ and LR- were 4·68 (3·67-5·69) and 0·21 (0·13-0·29) in Kenya and 4·15 (3·09-5·21) and 0·37 (0·28-0·46) in The Gambia, respectively. In both countries, the area under receiver operating characteristic curve for HBPM was above 75%. INTERPRETATION: HBPM showed moderate-to-high sensitivity and high specificity for detecting hypertension in two rural sub-Saharan African communities. HBPM represents a promising alternative for increasing hypertension awareness in rural sub-Saharan Africa.