Costs of 30-day potentially avoidable unplanned readmissions following discharge from general medicine wards: a South Australian retrospective cohort study

Objective: Directly influenced by hospital-related factors, potentially avoidable unplanned readmissions (PAURs) offer a more actionable indicator of care quality and safety than unplanned readmissions. Direct costs of PAURs are scarcely reported. This study estimates the direct costs of PAURs within 30 days of discharge and identifies factors associated with higher unplanned readmission costs. 

Methods: We retrospectively analysed hospitalisation data for all adult general medicine patients discharged alive from a South Australian hospital between 1 July and 30 September 2022 and readmitted to any state public hospital within 30 days. A panel of senior clinicians evaluated PAURs using pre-defined criteria. Costs were estimated using the National Hospital Cost Data Collection and inflated to 2024 Australian dollars. Predictors of cost were identified using a generalised linear model. 

Results: Of 375 readmitted patients, 78 readmissions were classified as PAURs. The total unadjusted unplanned readmission cost was $4,720,869, with PAURs accounting for $897,932 (19%). Mean costs were $11,512 (s.d. = $14,329) for PAURs and A$12,872 (s.d. = $19,089) for non-PAURs (P = 0.45). Readmission costs were higher among patients with congestive heart failure and chronic kidney disease (both P < 0.05). Adjusted mean cost per unplanned readmission (both PAURs and non-PAURs) was $13,703 (s.e. = $1112). PAURs were associated with a $3982 cost reduction (P = 0.037). Prior emergency department visits reduced costs (P = 0.017), whereas smoking (P = 0.043) and index admission length of stay (P < 0.05) increased costs. 

Conclusion: PAURs imposed substantial costs but were less expensive per admission than non-PAURs. Higher costs were observed among patients with congestive heart failure, chronic kidney disease, smoking, and longer index admissions. System-level transitional care strategies with targeted case management for high-risk, high-cost patients may enhance continuity of care, reduce readmission-related costs, and support more strategic resource allocation across the public healthcare system.