Sustainability of a 12-month lifestyle intervention delivered by community health workers in reducing blood pressure in Nepal: 5-year follow-up of the COBIN open-label, cluster randomised trial

Background: The sustainability and scalability of limited-duration interventions in low-income and middle-income countries remain unclear. We aimed to investigate the sustainability in reduction of blood pressure through a 12-month lifestyle intervention led by community health workers to reduce blood pressure in Nepal, 4 years after the intervention ceased. Methods: The Community-Based Intervention for Control of Hypertension in Nepal (COBIN) trial was a non-blinded, cluster-randomised trial done in Kaski, Nepal. Adults aged 25–65 years were eligible. People were excluded if they declined consent, were severely ill, unlikely to be in the community throughout the intervention, or pregnant. During the 12-month intervention, female community health volunteers (FCHVs) visited participants in the intervention groups and provided lifestyle counselling and blood pressure measurement every 4 months. At the end of the 12-month intervention, systolic blood pressure was significantly lower in the intervention group than in the usual care group in all cohorts, ranging from –2·3 mm Hg (95% CI –3·8 to –0·8) lower in those with normal blood pressure to –4·9 mm Hg (–7·8 to –2·0) in the hypertensive cohort. The primary outcome for this follow-up study was a mean change in systolic blood pressure from baseline to follow-up at 60 months. We did an intention-to-treat analysis. Findings: Between April 1, 2015, and Dec 31, 2015, 1638 participants were recruited in COBIN (939 [57·3%] assigned to intervention and 699 [42·7%] assigned to usual care). Of the 1468 (89·6%) who completed the 12-month assessments, we followed up 1352 (92·1%) participants at 60 months, between Oct 11, 2020, and May 5, 2022. 964 (71·3%) participants were women and 388 (28·7%) were men. From baseline to 60 months, the mean systolic blood pressure increased by 10·4 mm Hg (95% CI 9·1–11·6) in the intervention group and 6·0 mm Hg (4·6–7·5) in the usual care group (adjusted mean difference 4·1 mm Hg [2·2 to 5·8]). Interpretation: Lifestyle counselling and blood pressure monitoring by community health workers is effective in substantially reducing blood pressure while adults are being monitored in a trial but, following cessation of the intervention, this benefit is not maintained in the long term, with potential for harm. This finding could have important implications for funders and research communities to regularly target participants for education and follow-up at an optimal timepoint to reduce any likelihood of harm. Funding: Monash University (Melbourne, VIC, Australia) and the Jayanti Memorial Trust (Kathmandu, Nepal). Translation: For the Nepali translation of the abstract see Supplementary Materials section.