Warfarin Treatment and All-Cause Mortality in Community-Dwelling Older Adults with Atrial Fibrillation: A Retrospective Observational Study

OBJECTIVES: To investigate the relationship between warfarin treatment and different strata of all-cause mortality risk assessed using the Multidimensional Prognostic Index (MPI) based on information collected using the Standardized Multidimensional Assessment Schedule for Adults and Aged Persons (SVaMA) in community-dwelling older adults with atrial fibrillation (AF). DESIGN: Retrospective observational study. SETTING: Older community-dwelling adults who underwent a SVaMA evaluation establishing accessibility to homecare services and nursing home admission from 2005 to 2013 in the Padova Health District, Italy. PARTICIPANTS: Community-dwelling individuals with AF aged 65 and older (N = 1,827). MEASUREMENTS: Participants were classified as being at mild (MPI-SVaMA-1), moderate (MPI-SVaMA-2), or severe (MPI-SVaMA-3) risk of mortality using the MPI-SVaMA, a validated prognostic tool based on age, sex, comorbidity, cognitive status, mobility and functional disability, pressure sore risk, and social support. The association between warfarin treatment and mortality was tested using multivariate-and propensity score-adjusted Cox regression models, controlling for age, sex, all SVaMA domains, concomitant diseases, and drug treatments. RESULTS: Higher MPI-SVaMA scores were associated with lower rates of warfarin treatment and higher 3-year mortality. After adjustment for propensity score quintiles, warfarin treatment was significantly associated with lower 2-year mortality in individuals with MPI-SVaMA-1 (hazard ratio (HR) = 0.64, 95% confidence interval (CI) = 0.50-0.82), MPI-SVaMA-2 (HR = 0.68, 95% CI = 0.55-0.85), and MPI-SVaMA-3 (HR = 0.55, 95% CI = 0.44-0.67). Heterogeneity analyses confirmed that the effect of warfarin treatment was not different between MPI-SVaMA groups (P for heterogeneity = .48). CONCLUSION: Community-dwelling older adults with AF benefitted from anticoagulation in terms of lower all-cause mortality over a mean follow-up of 2 years, regardless of poor health and functional condition. Although this benefit can be ascribed to the treatment, it may also reflect better overall care.