Sex-specific association of comorbid heart failure on mortality after Alzheimer's disease diagnosis in older adults aged 75 years and above: A health insurance claims data analysis in Japan

Background: Research on the influence of heart failure on mortality after Alzheimer's disease diagnosis is limited. Objective To evaluate the association between comorbid heart failure and mortality following Alzheimer's disease diagnosis, particularly considering sex differences. Methods: We analyzed administrative claims data from Japan, involving 32,363 individuals (11,064 men and 21,299 women) aged 75 or older newly diagnosed with Alzheimer's disease, with 7% having comorbid heart failure. Cox proportional hazard models and population attributable fractions (PAFs) were used to evaluate the association between comorbid heart failure and mortality within one year following Alzheimer's disease diagnosis. Results: Individuals with Alzheimer's disease and heart failure had a multivariate-adjusted hazard ratio of 1.51 (95% confidence interval [CI], 1.32-1.73) for mortality during the one-year follow-up period compared to those with Alzheimer's disease and without heart failure. Subgroup analysis by sex revealed a higher mortality hazard ratio in women of 1.63 (95% CI, 1.36-1.95) than that in men of 1.39 (95% CI, 1.13-1.71). Further age and sex subgroup analysis indicated that women across all age brackets-75-79, 80-84, and >= 85 years-had higher mortality hazard ratios. The PAF for heart failure increased with age in both sexes, with women having higher PAFs than men, and the sex difference in PAF being most pronounced in the 75-79 age category (men: 1.4%, women: 4.0%). Conclusions: Hazard ratios and PAFs for mortality associated with comorbid heart failure in newly diagnosed Alzheimer's disease are higher in women than in men, which persists across all age subgroups.