The impact of unplanned reoperation on clinical and economic outcomes among hospitalized surgical patients: a DRG-adjusted real-world retrospective cohort study

OBJECTIVE: Unplanned reoperation is a recognized indicator of surgical quality, yet accurately estimating its true clinical and economic burden remains challenging due to inadequate case mix adjustment. This study aims to comprehensively evaluate the impact of unplanned reoperation on hospitalized surgical patients using Diagnosis Related Group (DRG) based adjustment. METHODS: A retrospective cohort study was conducted on surgical patients between 2022 and 2024, using data from the DRG database of a large tertiary general hospital with four districts. Unplanned reoperation was defined as an unplanned return to the operating room during the same hospitalization due to complications, procedural errors, or misdiagnosis. Primary outcomes were length of stay (LOS) and hospitalization costs; the secondary outcome was discharge to home under physician's order. DRG based frequency matching was performed to balance case mix. Multivariable linear regression and Fine-Gray competing risk models were used to estimate adjusted geometric mean ratios (GMR) and hazard ratios (HR). Subgroup and sensitivity analyses (propensity score matching and excluding short-stay patients) were conducted to assess robustness. RESULTS: Of 301,478 surgical patients, 775 (0.26%) underwent unplanned reoperation. After DRG-based matching, 2,325 patients (775 cases, 1,550 controls) were included. Unplanned reoperation was independently associated with prolonged LOS (adjusted GMR: 1.64; 95% CI: 1.55-1.74), increased costs (adjusted GMR: 1.51; 95% CI: 1.43-1.60), and a 53% lower likelihood of discharge to home (adjusted HR: 0.47; 95% CI: 0.42-0.53). The impact varied significantly by surgical specialty: orthopedics showed the greatest LOS prolongation (GMR: 2.49; 95% CI: 1.78-3.49), while cardiothoracic surgery and urology demonstrated the highest cost increases (GMR: 1.90 and 1.84, respectively). Non-cancer patients and those undergoing level 1-2 surgeries were particularly vulnerable. These findings remained robust in sensitivity analyses. CONCLUSIONS: Incorporating DRG-based adjustment enables a more accurate evaluation of the incremental clinical and economic burden associated with unplanned reoperations, including prolonged length of stay and increased hospitalization costs. These findings highlight that mitigating the impact of such reoperations, especially in procedures < 3 h, non-oncologic surgeries, grade 1-2 surgeries, orthopedic and cardiothoracic procedures, remains a crucial challenge that requires special consideration in clinical management.