Inpatient diagnosis clusters: analyzing hospital care in family practice.

Hospital care is an important component of family practice in the United States, but the study of this area has been impeded by the lack of a simple and clinically meaningful method of categorizing the diagnostic problems that make up the inpatient workload. This paper extends the method of diagnosis clusters--first used in the analysis of ambulatory care--to the hospital setting. Using the University of Southern California Medical Activities and Manpower Study of office-based general and family physicians, 52 clinically discrete diagnosis clusters were developed that include 78 percent of all principal diagnoses recorded in the hospital during the study interval. Fifty percent of all hospital encounters can be incorporated in only 15 clusters. Data clustered using this technique demonstrate that clinical problems such as ischemic heart disease and malignant neoplasms represent a major part of the family physician's hospital workload, a fact that has important implications for training and practice. Diagnosis clustering should facilitate further study of the hospital activities of primary care physicians.