Low vegetable consumption doubles the odds of stroke among people with hypertension: Findings from the SIREN Study in West Africa

Background: While hypertension is a primary risk factor for higher stroke risk, adequate vegetable consumption has been linked with a lower odds of stroke. However, it is unclear whether low/inadequate vegetable consumption could aggravate the odds of stroke among people with hypertension. This study assessed the interaction of low vegetable consumption and hypertension with stroke among West Africans. Methods: In this case–control study, 3684 stroke cases (aged ⩾ 18 years) matched for age ±5 years, sex, and ethnicity, with 3684 healthy controls were recruited across multiple sites in Nigeria and Ghana. Hypertension was defined using standard guidelines, and vegetable consumption was assessed with a food frequency questionnaire. Multivariable-adjusted conditional logistic regression and interaction models were used to estimate the odds ratios (OR) with a 95% confidence interval (CI) of stroke and the synergistic interaction of both low vegetable consumption (< 6 servings per week) and hypertension. The attributable proportion (AP), relative excess risk due to interaction (RERI), and synergy index (SI) were estimated at a two-sided P < 0.05. Results: Overall, the mean age was 59.0 ± 14.9 years, and 45.8% (3376) were female. Among stroke cases, the prevalence of low vegetable consumption and hypertension was 68.1% (2508) and 95.9% (3480), respectively. The multivariable-adjusted odds of stroke, given low vegetable consumption with hypertension, were OR = 25.66 (95% CI = 16.65, 39.54) with an RERI of 13.40 (95% CI = 7.21, 19.59), AP of 0.52 (95% CI = 0.44, 0.60), SI of 2.19 (95% CI = 1.82, 2.63), and a multiplicative interaction of about 50%; 1.51 (95% CI = 0.91, 2.49). Conclusion: The odds of stroke double with low vegetable consumption among people with hypertension in this population.