Swiss hospital financing with DRGs: Are there treatments/- combinations that are associated with profitability?

Objective: This study aims to investigate whether specific treatments or combinations of treatments are significantly associated with the profitability of Swiss acute-care hospitals under the current diagnosis-related group (S-DRG) reimbursement system, while accounting for differences between public and private institutions. Methods: A comprehensive panel dataset of 142 Swiss acute-care hospitals, spanning from 2015 to 2022, was utilized, combining detailed financial and clinical case-level data. Profitability was assessed through hospital-level net financial results excluding deficit-covering payments. All cases were assigned uniquely to a medically homogeneous service group or area, as determined by Swiss hospital capacity planning. Fixed-effects panel regression models analyzed the associations between service areas and profitability, while an Apriori association rule mining algorithm identified service group combinations associated with profitability. Results: From 2015 to 2022, overall hospital profitability margins declined continuously, with public hospitals consistently reporting lower profitability than private hospitals (net profitability margin: 0.75% vs. 1.61%), despite receiving substantial subsidies (CHF 67.1 million vs. CHF 4.1 million). The primary panel regression revealed that three service areas are significantly associated with hospital profitability: Ear, nose and throat (16,778 CHF; p﹤0.05), gynecology (27,456 CHF; p﹤0.01), and heart (10,725 CHF; p﹤0.01). The Apriori algorithm identified that the combination of the following service groups is most strongly linked to profitability: AUG1.2 (orbit, eyelids, tear ducts), BEW10 (plexus surgery), and GEF2 (interventional and endovascular vascular medicine; support: 0.051, confidence: 0.935, lift: 1.615). Conclusion: The analysis of hospital profitability based on the treatments and combinations of treatments performed indicates that the S-DRG reimbursement system is relatively fair. However, across all analyses, the heart service area is primarily associated with profitability, while the serious injury service area is mainly associated with losses. Therefore, minor adjustments to the S-DRG cost weights should be made to reduce this imbalance.