O13 ASSOCIATION OF SECONDHAND SMOKE EXPOSURE IN RELATION TO HYPERTENSION TREATMENT STATUS WITH STROKE OCCURRENCE IN GHANA AND NIGERIA

Background and objective: It is unclear whether secondhand smoke exposure (SHSE) in hypertensive states with a disproportionate gap in hypertension treatment status is fuelling the epidemic of stroke in sub-Saharan Africa. This study, therefore, assessed the association of SHSE in relation to hypertension treatment status with stroke occurrence among West Africans. Methods: The Stroke Investigative Research and Educational Network (SIREN) is a case-control study across 16 study sites in Ghana and Nigeria. Cases were acute stroke (n =3684) with age- and sex-matched stroke-free controls (n =3684). Hypertension definition was based on standard guidelines, and SHSE was based on self-reported exposure to smoke from a burning cigarette or exhaled from a smoker in any indoor area. We evaluated the associations of untreated hypertension, treated but uncontrolled hypertension, and controlled hypertension at BP of <140/90 mmHg with odds of stroke occurrence. Multivariable-adjusted logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) of the risk of stroke by hypertension treatment and SHSE status. Results: Overall, mean age was 59.0±14.9 years, and 54.2% were male. Among stroke cases, the prevalence of SHSE was 352 (20.7%), and the frequencies of no hypertension, untreated hypertension, treated but uncontrolled hypertension, and controlled hypertension were 4.0%, 47.7%, 37.1%, and 9.2%. The aOR and PAR (95% CI) for untreated hypertension were 6.58 (5.15-8.41) and 35.4% (33.4-37.4); treated but uncontrolled hypertension was 9.95 (7.60-13.02) and 35.9% (34.2-37.5); and controlled hypertension was 5.37 (3.90-7.41) and 8.5% (7.6-9.5) respectively. The aOR (95% CI) of stroke, given exposure to secondhand smoke, was 1.15 (0.94-1.41), while among untreated hypertensives and treated but uncontrolled hypertensives was 1.54 (0.99-2.37) and 1.15 (0.48-1.46) respectively. Conclusion: SHSE with hypertension significantly aggravated the odds of stroke occurrence, particularly when hypertension is untreated. Implementing targeted multi-sectoral interventions that advocate for clean air and aggressive hypertension treatment can potentially reduce the escalating burden of stroke in Africa.