Background: Previous studies have shown the validity of Adjusted Clinical Groups (ACGs) in the primary care setting, but the absence of administrative databases is a problem for the implementation of this system.
Objectives: To assess the validity of physicians' notes in computerized clinical records for the implementation of ACGs, and to determine the ability of the ACGs system to explain the use of primary care resources in real conditions of the daily practice.
Research design: Cross-sectional study.
Subjects: All patients who were continuously assigned to 56 physicians from public primary health care centers in the Bizkaia Basque Country (Spain) over at least a 6-month period were included.
Measures: Patients were classified by means of the ACGs system using the ICD-9-CM diagnostic codes according to three scenarios: (1) those annotated by the physicians in the computerized medical record, (2) codification of computerized medical records diagnoses by the research team, and (3) computerized medical records diagnoses complemented by hospital discharge codes.
Results: The ACGs system explained more than 50% of the variance in visits made to primary care physicians, 25-40% of prescriptions, 25-30% of referrals and requests of laboratory tests, and 14-16% of radiographs. The coefficients of determination remained almost invariable after the addition of hospital diagnoses or correction of coding errors. Fifty-two physicians (93%) registered their patients' diagnosis quite acceptably, whereas only 29 (52%) included this datum in the prescriptions.
Conclusions: The ACGs system is a useful tool to explain the use of primary care services in a national health care system within the European Union. The implementation of ACGs from the physician's annotations in the computerized medical records is feasible.