Preadmission morbidity and healthcare utilization among older adults with potentially avoidable hospitalizations: a Danish case-control study.

Purpose: Examine preadmission diagnoses, medication use, and preadmission healthcare utilization among older adults prior to first potentially avoidable hospitalizations.

Methods: A nationwide population-based case-control study using Danish healthcare data. All Danish adults aged ≥ 65 years who had a first potentially avoidable hospitalization from January 1995 through March 2019 (n = 725,939) were defined as cases, and 1:1 age- and sex-matched general population controls (n = 725,939). Preadmission morbidity and healthcare utilization were assessed based on a complete hospital diagnosis history within 10 years prior, and all medication use and healthcare contacts 1 year prior. Using log-binomial regression, we calculated adjusted prevalence ratios (PR) with 95% confidence intervals (CI).

Results: Included cases and controls had a median age of 78 years and 59% were female. The burden of preadmission morbidity was higher among cases than controls. The strongest associations were observed for preadmission chronic lung disease (PR 3.8, CI 3.7-3.8), alcohol-related disease (PR 3.1, CI 3.0-3.2), chronic kidney disease (PR 2.4, CI 2.4-2.5), psychiatric disease (PR 2.2, CI 2.2-2.3), heart failure (PR 2.2, CI 2.2-2.3), and previous hospital contacts with infections (PR 2.2, CI 2.2-2.3). A high and accelerating number of healthcare contacts was observed during the months preceding the potentially avoidable hospitalization (having over 5 GP contacts 1 month prior, PR 3.0, CI 3.0-3.0).

Conclusion: A high number of healthcare contacts and preadmission morbidity and medication use, especially chronic lung, heart, and kidney disease, alcohol-related or psychiatric disease including dementia, and previous infections are strongly associated with potentially avoidable hospitalizations.