Data sources
Data were retrospectively extracted from the French Hospital Medical Information database (Programme de Médicalisation des Systèmes d’Information – PMSI). The French PMSI-MCO database covers all overnight or day hospitalizations in the public and private French hospitals19. Each hospital stay results in a production of a standard discharge summary (“Résumé de Sortie Standardisé” RSS) following inpatient conventional stays, day-hospital stays or sessions. The RSS is then anonymized to become the RSA (“Résumé de Sortie Anonyme”). The RSA contains information’s on the patient characteristics (gender, age, residence code), on the main diagnosis that led to hospital admission, on the nature of the treatment and work-up (examinations) carried out, on comorbidities and on complications. Diagnoses are coded using the International Classification of Diseases, 10th revision (ICD-10)20 either as primary- (PD: the condition for which the patient was hospitalized), related- (RD: any underlying condition which may have been related to the PD), or significant associated-diagnoses (SAD: comorbidities or complications which may affect the course or cost of hospitalization). For each DRG produced, the hospital receives a payment which amount corresponds to the national tariff of DRG, intending to cover all hospital expenses.
Since a patient may have several hospital stays during a year, it is possible to count the number of stays or the total cost of hospitalization per year, by linking all his hospital stays based on his patient’s identification number.