Combined association of drinking water salinity and psychosocial distress with hypertension among reproductive-aged women in coastal Bangladesh: a population-based cross-sectional study

Background Climate change-driven salinity intrusion into drinking water poses a structural risk for hypertension among women in coastal Bangladesh. Psychosocial distress from climate stressors may amplify this effect, but how these two factors interact jointly remains understudied. Methods This population-based cross-sectional survey included 4,693 ever-married women aged ≥ 18 years in coastal Bangladesh, using probability proportionate to size sampling in high- and low-salinity areas. Hypertension was defined as SBP ≥ 140 mmHg, DBP ≥ 90 mmHg, or antihypertensive use. Psychosocial distress was measured by the PHQ-ADS composite (GAD-7 + PHQ-9; low: 0–19, moderate: 20–29, severe: ≥30). Drinking water sodium was quantified continuously (per 100 mg/L) and categorically (< 1000, 1000 2000, > 2000 mg/L). Multivariable logistic regression estimated adjusted odds ratios (AORs), controlling for age, education, wealth, salinity zone, disaster exposure, and income loss. Effect modification was tested via interaction terms and stratification. Results Hypertension prevalence was 24.9%; moderate/severe distress affected 75.4%. Significant independent associations included moderate distress (AOR 1.86; 95% CI 1.51–2.28), severe distress (AOR 1.88; 95% CI 1.51–2.32), and sodium (AOR 1.10 per 100 mg/L; 95% CI 1.02–1.35). Significant multiplicative interaction occurred between high sodium (> 2000 mg/L) and severe distress (interaction AOR 1.29; 95% CI 1.01–1.56; p = 0.011), with stratified AOR 2.45 (95% CI 1.79–3.36) for combined exposure. Sensitivity analyses confirmed robustness (combined exposure AORs 1.95–3.10). Conclusions Psychosocial distress modifies the hypertension risk from climate-driven drinking water salinity among coastal Bangladeshi women, suggesting combined association. Integrated mental health screening, psychosocial support, and salinity mitigation are urgently needed to drive hypertension prevention and climate-health adaptations.