Comparison of Screening Tools for Coronary Artery Disease

Design: The proposed study is a cross sectional study of a population sample of 450 subjects aged > 40 years, and stratified by gender, residing in 12 randomly selected communities in Karachi, Pakistan.

The target population for this study would be drawn from an existing population based study entitled "Population based strategies for effective control of high blood pressure in Pakistan" (parent study), conducted by the primary supervisor and study director (TJ) in Karachi Subjects aged > 40 years would be eligible. Detailed information on each participant would be obtained from data collected for the parent study. This includes a) socio-demographic characteristics such as level of education, occupation, economic status, ethnicity, tobacco use , physical activity defined on the basis of International Physical Activity Questionnaire, dietary habits (food frequency questionnaire), family history of CAD, and the WHO standard Rose questionnaire (RQ) for coronary artery disease (CAD) (b) anthropometry including height, weight, waist and hip circumference (c) laboratory tests including fasting blood glucose, lipid profile, serum creatinine, and urine albumin to creatinine ratio. The community health workers (CHW) would administer RQ and obtain 12-lead EKG. They would give an appointment to subjects for MPI at the Aga Khan University Hospital. Each individual will then go through an exercise treadmill test (symptom limited Bruce or modified Bruce protocols) if able to walk, or pharmacological stress by the infusion of dobutamine or dipyridamole if unable to walk. The results of MPI study would be delivered to the subjects with interpretation by cardiologists, and referral to a physician (as appropriate).

Classification of Screening instruments: ECG will be Minnesota coded by two trained and independent coders, and discrepant reports will be resolved with a third independent coder. All cases of probable or possible CAD on Minnesota coding of ECG would be classified as "MC ECG positive for CAD" RQ will be coded according to standardized criteria into "positives for "angina" and "history of possible infarction" . Presence of either one would be classified as "RQ positive for CAD".