Type Classification Based on Inpatient Ratio According to Major Diagnosis Category of Group III in the Diagnosis...

The target was 1,283 hospitals in group III of medical institutions. Using the Diagnosis Procedure Combination (DPC) data and the inpatient ratio according to the major diagnosis category (MDC), group III hospitals were clarified on the basis of the Mahalanobis distance (D(2)) calculated using the Mahalanobis·Taguchi (MT) method.

About 50 hospitals with the top inpatient ratio in each MDC and 1,233 other hospitals. The following were examined. 1) Significant difference between DPC data and inpatient ratio. 2) Distribution of D(2). 3) Classification based on the distribution of D(2).

The top hospital was small scale, and there were few cases of emergency hospitalization, operation, general anesthesia induction, and chemotherapy. The number of cases involving the respiratory system, circulatory system, digestive and hepatobiliary systems, metabolic system, muscloskeletal system, kidney and urinary tracts was high with an inpatient ratio of more than 90%. On the bases of the distribution of D(2), the hospitals were classified into four types. Group one consisted of 213 special hospitals that showed high inpatient ratios of cases involving the nervous system, respiratory system, digestive and hepatobiliary systems, muscloskeletal system, injuries and burns. Group two consisted of 195 associate special hospitals that showed high inpatient ratios of cases involving the circulatory organ, metabolic system, kidney and urinary tracts, pediatric diseases, and mental diseases. Group three consisted of 223 hospitals for the seven remaining diseases. Group four consisted of 652 hospitals showing other distributions of D(2).

Classification of hospitals to four types was possible by the MT method depending on the medical treatment results.