The purpose of this paper is to determine whether, in a geographically diverse sample of people 65 years or age or older living in one of five states, the appropriateness of the use of coronary angiography, upper gastrointestinal endoscopy, or carotid endarterectomy can be predicted from easily obtainable data on the characteristics of patients, physicians, or hospitals. The data for this study were obtained from medical records of Medicare patients who underwent one of these procedures. Income was measured using ZIP-code area data. Noting that the data were collected in 1981, the authors state, "We believe that the conclusion based on these analyses are relevant to current policy decisions. For the conclusions to be wrong today, both the level of appropriateness and the relation of appropriateness to the predictor variables would have to have changed."

Among patients who underwent one of these procedures, there were no consistent predictors of the appropriateness of their use. For angiography, patients' income and age were associated with appropriate use. For endoscopy, patients' sex and physicians' board certification were associated with appropriate use. For endarterectomy, physicians' volume of procedures, teaching hospital use, and number of beds in the hospital predicted appropriate use. (It is notable that for endarterectomies, physicians' performing a higher volume of procedures was the most important predictor of inappropriate use of this procedure. Further, this was because these physicians operated on the less sick, asymptomatic patients.) Patient race did not significantly predict appropriate use of any of the three procedures.

The authors conclude that appropriateness of care cannot be closely predicted from many easily determined characteristics of patients, physicians, or hospitals. If appropriateness is to be improved it must be on an individual patient, physician, and hospital basis. They state that the data suggest that "specific subgroups of the insured elderly population do not systematically receive more or less appropriate care." (presumably meaning among patients who receive one of the three studies procedures.) They further emphasize, "it is reassuring to know that, at least for the insured elderly, stereotypical characteristics of people and their physicians do not explain appropriateness. We are all in the same predicament, and some degree of equity in the likelihood of undergoing an appropriate or inappropriate procedure has been attained." (This statement reflects findings from the authors' previous study which demonstrated that about one quarter of coronary angiographies and upper gastrointestinal endoscopies and two third of carotid endarterectomies were performed for reasons that were less than medically appropriate.)