ORIGINAL ARTICLE A Primary Care Experience of Open Access to Exercise Stress Test C J Ng, MMed (Fam Med), E M Khoo, MRCGP Department of Primary Care Medicine, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur SUMMARY This study described the practice profile of an open access exercise stress test (EST) service to the primary care physicians at a teaching hospital in 2000. We performed a retrospective review of all ESTs ordered and conducted by the primary care physicians. A total of 145 ESTs were conducted, of which 80.7% were referred for assessment of chest pain. Proportions of positive, negative, uninterpretable and inconclusive ESTs were: 22.1%, 52.8%, 18.1% and 6.9%. Typical chest pain was independently associated with a positive EST in this study (p=0.008, OR 5.50, 95% CI 1.56- 19.37). Although referral to the open access EST service seemed appropriate, there is a need to reduce the number of uninterpretable and inconclusive results. KEYWORDS: Exercise stress test, primary medical care, chest pain, coronary artery disease INTRODUCTION Chest pain is a common diagnostic problem in primary care and electrocardiogram (ECG) has been frequently used in primary care to diagnose or exclude the possibility of coronary artery disease (CAD). Although ECG is relatively cheap, accessible and easy to perform, it has a low sensitivity! making it a less useful test to rule out CAD. As a result, exercise stress test (EST) is increasingly being used for the diagnosis of CAD among patients presenting with chest pain. A meta-analysis by Gianrossi et al showed that exercise- induced ST depression had a mean sensitivity of 68% (23- 100%) and a specificity of 77% (17-100%), using coronary angiography as the gold standard 2 • Open access to ESTs is available to primary care physicians in some countries 3 • Although it can serve as a useful adjunctive tool to the diagnosis of CAD, there are inherent problems in the test; the accuracy of the test depends on appropriate patient selection, functioning equipments and trained staff to conduct the test and interpret the results'. To ensure diagnostic accuracy, it is crucial for patients to achieve clinical targets, such as reaching maximal predicted heart rate and stage 4 of the exercise. In Malaysia, EST service is restricted only to main hospitals. There are few centres that allow primary care physicians to gain direct access to this service. At the University of Malaya Medical Centre, the cardiology unit runs the EST service. This service is also opened to primary care physicians who work in the outpatient clinic of the hospital. The primary care physicians conduct ESTs two afternoons per week for patients who are referred from their own clinic. This set-up provides an opportunity to study an open access service of EST in a primary care context. The objectives of this study were to describe the practice profile of this unique service, in particular looking at the indications, barriers and outcome of ESTs. MATERIALS AND METHODS This study reviewed all ESTs performed by primary care physicians in the year 2000. We obtained the complete list of ESTs from the cardiology laboratory. We retrieved the EST tracings, reports and medical records of all patients during this period. A team of cardiologists from the hospital independently reported on the baseline ECGs and outcome of the ESTs (positive, negative, inconclusive and un- interpretable) based on the American Heart Association guideline'. Other information such as achievement of target maximal heart rate [(220-age) x 0.85] and reasons of termination were extracted from the EST reports. Clinical information (age, gender, ethnicities, indications of EST, risk factors, follow-up and final diagnosis) were collected from the medical records. This study was approved by the hospital ethics committee. We analysed the data using the SPSS 11.5 software. Categorical data were presented in percentages while continuous data were presented as means with standard deviations. Associations between independent variables and outcome of EST were determined using chi-square test for categorical variables and student t-test for continuous variables. We analysed the predictors of positive EST using a binary logistic regression model. RESULTS Patients' profile In the year 2000, a total of 145 ESTs were conducted for patients attending the primary care clinic in the hospital. The mean age of the patients was 52.9 years (SD=9.7, range 24-78 years). Majority of them were male (66.2%) with an equal distribution of ethnicity (Chinese 33.8%; Indian 33.8%; Malay 29.4%). The proportions of patients with cardiovascular risk factors (RF) were: hypertension 44.1% (n=64), dyslipidaemia 40% (n=58), diabetes mellitus 24.8% (n=36), smoking 16.6% (n=24) and family history of coronary artery disease 10.3% (n=15). 76.6% of the patients had at least This article was accepted: 31 July 2007 Corresponding Author: Khoo Ee Ming, Department of Primary Care Medicine, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur Med J Malaysia Vol 62 No 3 August 2007 241