Different from what the textbooks say: how GPs diagnose coronary heart disease.

Background: In patients with chest pain, GPs have to identify those with coronary heart disease (CHD) to arrange for further investigation and treatment. Previous studies have shown that only between 8% and 18% of patients have CHD. In primary care, the history is the most important diagnostic tool. However, there are only few studies exploring diagnostic criteria that GPs actually use in their daily practice.

Objective: To identify GPs' diagnostic criteria for diagnosing CHD in patients with chest pain.

Methods: In a semi-structured interview, 23 GPs were asked to describe their individual diagnostic criteria in two of their patients with chest pain they had prospectively identified. Interview data were taped, transcribed and analysed qualitatively.

Results: Histories of 39 patients were described, of which 17 patients were thought to have CHD and/or an indication for an emergency hospital admission. GPs mentioned the person-specific discrepancy, that is differences in behaviour or a different appearance of a patient in comparison to previous consultations, as an important diagnostic criterion. Known risk factors for CHD and past illness behaviour also influenced the GPs' diagnoses.

Conclusion: Apart from classical textbook criteria, GPs make use of their prior knowledge of individual patients in a specific way. Discrepancies between previous and actual consultations alert the GPs for serious diseases. At the primary care level, medical practitioners use criteria that differ from secondary or tertiary care.