Impact of Announced but Unimplemented Bundled Payment Rules on Hospital Coding Practices in France

Bundled Payment for Care Improvement (BPCI) models aim to reduce healthcare costs by improving patient pathways and enhancing care coordination. This study investigates the impact of the announced—but not implemented—BPCI reform in France, which was decided in 2019 but never enacted during the study period (2013–2022). The model proposed adjustments to base payments to account for patient comorbidities. In the French context, it also aimed to reduce reliance on rehabilitation hospitals by incorporating comorbidity data into payment calculations. Despite the absence of actual implementation or financial transfers, significant changes in hospital coding practices were observed in anticipation of the reform. We examine how the announcement of a potential additional payment influenced hospital coding behavior, even without formal policy adoption.To measure this behavioral response, we employ a difference-in-differences (DiD) approach, focusing on two key dimensions: (1) Coding behavior for patients not admitted to inpatient rehabilitation after acute care; (2) Coding behavior for patients admitted to rehabilitation following acute care. Analyzing over one million hip replacement cases, the study reveals a sharp rise in the coding of socio-environmental factors—changes seemingly driven more by anticipated financial incentives than by actual clinical complexity. We find that subjective coding is more prone to overcoding than objective clinical characteristics. Our findings underscore a critical issue: to preserve the integrity of bundled payment models and ensure they truly improve care quality and efficiency, policymakers must urgently reconsider the role of coded variables in reimbursement decisions.