“Hospital use may be related to demography, morbidity, medical resources, access, selection for care, and physician practice patterns. We cannot distinguish these effects using admission data alone, and we cannot accurately partition the systemic variance into identifiable components. The major factor appears to be differing criteria used by physicians for hospital admission and surgical intervention.”

“There is little evidence that incidence of surgical disease is the main source of variation in use of discretionary surgery. Rather, variations reflect differing medical opinion on appropriate use. Without evaluation, excessive use cannot be distinguished from underservice.”