Prevalence and factors associated with inappropriate use of treadmill exercise stress test for coronary artery disease: a cross-sectional study

BACKGROUND: In some countries, the public health system has less availability when compared to the population covered by health insurance. In addition, inappropriate referrals for treadmill exercise stress test increase spending and lead to unnecessary interventions. We aim to determine the prevalence and characteristics of inappropriate referrals for treadmill exercise stress tests in the assessment of coronary artery disease (CAD), considering public and private health systems scenarios. METHODS: A cross-sectional design was used to describe the frequency of inappropriate use of exercise testing in the diagnosis of CAD and to determine its predictors. We consecutively enrolled 191 patients from two outpatient facilities in Northeast Brazil. For inclusion, the exercise testing should be referred for the assessment of CAD. We performed logistic regression models to identify independent predictors of inappropriate use. RESULTS: Treadmill exercise stress tests were rated as inappropriate in 150 (78 %) patients. The majority of patients had low or very low pre-test probability of CAD. Presence of hypertension, diabetes and dyslipidemia were more frequent in the appropriate than inappropriate indications (71 %, 19 % and 29 % versus 43 %, 8 % and 16 %, respectively). Tests performed both at the public and private system showed high prevalence of inappropriate examinations, higher in the latter (57 % versus 87 %, P < 0.001). The private health system was the major independent predictor of inappropriate referral, consistent in all regression models (when adjusting for clinical variables, OR = 4.3; P < 0.001). CONCLUSION: The vast majority of treadmill exercise stress test referrals in the assessment of CAD were inappropriate. The availability of the method and not the estimate probability of CAD appear to be the underlying condition for a treadmill test referral.