The Validity of the Questionnaire Diagnosis

Abstract

Validation of a mailed questionnaire concerning angina pectoris has been performed using 69 male twins with the diagnosis “angina pectoris” according to the questionnaire. Of these, 22% could be verified at the clinical examination. If all clinically suspected cases were included together with the cases with a pathological electrocardiogram the confirmation rate was 57%. The confirmation rate was higher, but not significantly so, if the criteria for angina pectoris were altered so that only those with central chest pain were included. The frequency of pathological ECGs in cases with a clinical diagnosis of angina pectoris was significantly higher than in those with a questionnaire diagnosis, which indicates that the validity of the clinical diagnosis is greater. The results indicate that the questionnaire is very useful for screening cases with coronary heart disease. If it is used at prevalence studies or effect studies, one has to be aware of the relatively high frequency of false-positives.