Programme no. 435-OP
Quality Improvement
Use of exercise tests in primary care: importance for referral decisions and possible bias in the decision process; a prospective observational study
Gunnar Nilsson*1, Eva Samuelsson2, Thomas Mooe3, Lars Söderström4
1Allmänmedicin,Folkhälsa och klinisk medicin, Umeå universitet,Umeå,Sweden, 2Allmänmedicin,Folkhälsa och klinisk medicin, Umeå universitet,Umeå,Sweden, 3Medicin,Folkhälsa och klinisk medicin, Umeå universitet,Umeå,Sweden, 4Unit of Research, Education and Development,Östersund Hospital,Östersund,Sweden
* = Presenting author
Objectives: We evaluated the results of exercise tests for selection of patients to cardiologic care, and if referral decisions were biased by sex, socioeconomy or age.
Background: Medical decisions are usually based on estimates of pre-test probability, which may be affected by irrelevant conditions, resulting in biased decisions that may be problematic for patients and providers of health care.
Results:

Positive/inconclusive exercise tests and exertional chest pain predicted referral in men and women. Of 865 participants, patients with positive, inconclusive, or negative exercise tests were referred to cardiologists in 67.3%, 26.1%, and 3.5% of cases, respectively. Overall, there was no significant difference in referral rates related to gender or socioeconomic level. Self-employed women were referred more frequently compared to other women (odds ratio (OR) 3.62, 95% confidence interval (CI) 1.19-10.99). Among non-manual employees, women were referred to cardiologic examination less frequently than men (OR 0.40, 95% CI 0.16-1.00; p = 0.049; ORs adjusted for age, exertional chest pain, and exercise test result). In patients with positive exercise tests, the referral rate decreased continuously with age (OR 0.48, 95% CI 0.23-0.97; adjusted for cardiovascular co-morbidity). Cardiovascular events occurred in 22.2% (4/18) of non-referred patients with positive exercise tests; 56% (10/18) of these patients were not considered for cardiologic care, with continuity problems in primary care as one possible contributing cause.

Material/Methods:

We designed a prospective observational study of 438 men and 427 women from 28 Swedish primary-care clinics who were examined with exercise testing for suspected coronary disease. All participants were followed-up with respect to cardiologist referrals and cardiovascular events (hospitalisation for unstable angina, myocardial infarction, and cardiovascular death) within six months and revascularisation within 250 days. Variables associated with referral were identified by multivariable logistic regression. Socioeconomic status was determined by educational level and employment.

Conclusion: Exercise tests are important for selecting patients for referral to cardiologic care. Interactions between gender and socioeconomic status affected referral rates. In patients with positive exercise tests, referral rates decreased with age. Patients with a positive stress test are at high risk for cardiovascular events, and reasons for non-referral should be appropriately documented
Points for discussion:

An increased awareness of possible biases regarding age, gender, and socioeconomic status, which may influence medical decisions, is necessary.