Objectives: To study risk factors for and likelihood of unplanned hospital admission and readmission in persons aged >65 years in Catalonia, Spain.
Study design: Retrospective cohort study.
Methods: We used data from clinical records of the primary care centers, pharmacy database, and hospital discharge records for persons aged >65 years registered in primary care centers of referral hospitals in the Baix Llobregat healthcare area. Unplanned hospital admission was defined as any unscheduled hospitalization in 2008; unplanned readmission was defined as any unscheduled admission occurring within 6 months after discharge date of index admission. Logistic regression analysis was used to identify predictors of unplanned hospital admission and readmission.
Results: The population included 28,430 individuals. Among them, 2103 (7%) experienced an unplanned admission and 365 (1.3%) an unplanned readmission. The readmission rate for the admitted population was 18.7%. The strongest predictive factor of unplanned admission was >2 admissions in the previous 2 years (odds ratio [OR] 24.9, 95% confidence interval [CI] 16.0-38.7 for 2007; OR 15.6, 95% CI 8.6-28.0 for 2006). Factors associated with unplanned readmission were aged >80 years (OR 4.6, 95% CI 3.1-7.1) and >2 admissions during the previous year (OR 20.4, 95% CI 14.1-29.5). The area under the receiver operating characteristics curve was 0.78 for unplanned admission and 0.85 for unplanned readmission in the development sample and 0.76 and 0.81, respectively, in the validation sample.
Conclusions: Aged persons and those who used more hospital services in previous years had a higher probability of hospital admission and readmission.