Predictors of avoidable and unavoidable hospital admissions in older adults: a 15-year population-based cohort study

We examined sociodemographic, clinical, and functional characteristics influencing avoidable and unavoidable hospital admissions in older adults over 15 years. The study included 3166 participants aged 60+ years from the Swedish National Study on Aging and Care in Kungsholmen. Hospital admissions were identified through national registers and classified as avoidable using official Swedish criteria. Multistate models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for both admission types. During the 15-year follow-up, the incidence rates of avoidable and unavoidable hospital admissions were, respectively, 5.74 and 35.17 per 100 person-years. Avoidable admissions due to chronic conditions were more common than those due to acute conditions (3.94 vs. 1.80 per 100 person-years over 15 years). Women had lower risk of both avoidable and unavoidable admissions compared to men (HRs range 0.46-0.76), while being unpartnered increased the risk for both hospitalization types (HRs range 1.13-1.33). Receiving formal care lowered the risk of unavoidable admissions (HR 0.78, 95% CI 0.73-0.84), whereas informal care increased the likelihood of avoidable admissions due to chronic condition (HRs range 1.17-1.34). Multimorbidity, slow gait speed, and polypharmacy associated strongly with avoidable admissions (HRs range 1.41-2.50). Conversely, cognitive impairment and disability lowered risk of avoidable admissions for chronic conditions (HRs range 0.62-0.83). Multimorbidity, slow gait speed, and polypharmacy predicted higher risks for avoidable admissions from chronic conditions, while disability and cognitive impairment showed lower risks. These findings underscore the need for timely and comprehensive evaluation strategies to reduce the burden of avoidable hospital care.