Coronary revascularisation outcome questionnaire (CROQ): development and validation of a new, patient based measure of outcome in coronary bypass surgery and angioplasty.

OBJECTIVE To describe the development and scientific validation of a new patient based measure, the coronary revascularisation outcome questionnaire (CROQ), to evaluate health outcomes and quality of life before and after coronary artery bypass grafting and percutaneous transluminal coronary angioplasty. DESIGN AND SETTING Psychometric validation study conducted with patients from three hospitals in the UK. PATIENTS Two independent field tests were conducted by postal survey of 714 patients before and 1329 patients after coronary revascularisation to evaluate the measurement properties of the CROQ. METHODS Qualitative methods including patient interviews were used to develop questionnaire content. A full psychometric evaluation was performed on the survey data. RESULTS Psychometric tests with the application of stringent criteria confirmed the acceptability (low missing data, good response rates), scaling assumptions (good item convergent and discriminant validity), reliability (good internal consistency and reproducibility), validity (good content and construct validity), and responsiveness of the CROQ. CONCLUSIONS The CROQ is a practical and scientifically sound patient based measure of outcome developed using psychometric methods. It captures aspects of recovery not addressed in other cardiac questionnaires and has been shown to be a highly responsive instrument that will be useful in evaluating outcomes in clinical trials.