Development of a patient classification system for inpatient rehabilitation in Switzerland

Background: Inpatient care in Swiss rehabilitation clinics is currently reimbursed by daily tariffs without any patient classification. The new Health Insurance Act (KVG) mandates the introduction of a national tariff system that is differentiated by intensity of care. While such a system has already been introduced in acute hospital care (SwissDRG) no similar regime has yet been developed for inpatient rehabilitation. We develop a patient classification system (PCS) for neurological rehabilitation that assigns patients to different cost groups based on predicted intensity of care. Methods: Information on patient characteristics and intensity of care is collected at randomly selected weeks of all treatment episodes in participating rehabilitation clinics. Patient characteristics included standardized assessments of independence in activities of daily living (ADL), comorbidities, pain level, reason for hospitalization and socio-demographic characteristics. Intensity of care was measured by the time different professional groups (nurses, medical doctors, physiotherapists, etc.) spent on the care of selected patients and by other variable costs such as the cost of medication. Statistical analysis was carried out in order to identify patient characteristics best predicting average daily costs and to develop a grouper most accurately assigning patients to single cost groups. Goodness of fit was measured by mean average predictive error (MAPE) and misclassification rate (MCR). Results: Information on patient characteristics and intensity of care was collected for 691 patient weeks in 7 rehabilitation clinics. ADL score and the number and degree of comorbidities are identified as main cost predictors. We develop a PCS with 4 cost groups forming quartiles of average daily costs per patient. Patients are assigned to cost groups by a weekly assessment of patient characteristics. Average costs differ by a factor of 2.72 between patients in the lowest and the highest cost group. Mean daily variable costs in the 4 cost groups are CHF 330, CHF 436, CHF 620 and CHF 948. Compared to a uniform daily tariff MAPE is reduced from 63% to 38%, and MCR is 37%. Discussion: The PCS will be used as a basis for a new tariff system in inpatient rehabilitation. The PCS sets incentives for an appropriate provision of services to patients with above and below average daily costs. The lack of an incentive to shorten length of stay is alleviated by the fact that inpatient rehabilitation has to be authorized by health insurers. Funding: The study was funded by the Commission for Medical Tariffs of the Swiss accident insurers and the association of Swiss hospitals H+.