Associations of baseline use of fish oil with progression of cardiometabolic multimorbidity and mortality among patients with hypertension: a prospective study of UK Biobank

Purpose The role of fish oil in the prognosis of hypertensive patients is unknown. This study investigated the associations of fish oil supplementation with the progression of cardiometabolic multimorbidity (CMM) and mortality among patients with hypertension. Methods Based on UK Biobank, we enrolled participants with hypertension and free of other cardiometabolic diseases. The exposure was baseline use of fish oil derived from questionnaires at baseline. The primary outcomes were the incidence of CMM and all-cause mortality. Competing risk models and flexible parametric proportion-hazards models were fitted to assess the adjusted hazard ratios (HRs) for the risk of CMM and mortality outcomes, respectively. Results Among 81,579 participants involved [50.37%, men; mean age, 59.38 years (standard deviation, 7.23 years)], 15,990 CMM events and 6456 all-cause deaths were reported (median follow-up, 12.23 years). In multivariable-adjusted models, baseline use of fish oil was associated with 8% lower risk of CMM [95% confidence interval (95% CI) 0.89-0.96, P < 0.001] and 10% lower risk of all-cause mortality (95% CI 0.85-0.95, P < 0.001). Conclusion In individuals with hypertension, baseline use of fish oil was associated with a reduced risk of CMM and all-cause mortality, and further clinical trials are needed to prove this hypothesis.