Peer review in diabetes and hypertension: the relationship between care process and patient outcome.

To assess the effect of physician performance on patient outcomes, we examined the relationship between performance of essential care items and several patient outcomes in hypertension and diabetes. A group of internists in private practice selected the criteria and allowed their records to be reviewed to ascertain their adherence to these criteria and their patients' outcome status. Among all physicians and patients, adherence to criteria was not associated with a composite measure of control status or with blood sugar level in diabetes, or with blood pressure control in hypertension. Peer review groups should recognize the limitations in measuring care process and patient outcomes, and that adequacy of physician performance does not necessarily predict how well the patient will do.