Non-invasive screening for coronary artery disease in asymptomatic diabetic patients: a systematic review and meta-analysis of randomised controlled trials

It is unclear whether non-invasive screening of asymptomatic diabetic patients for coronary artery disease (CAD) may improve cardiac outcomes. Thus, we performed a systematic literature review and meta-analysis of randomised controlled trials (RCT's) on this topic. We searched appropriate RCT's in five online databases (PubMed/MEDLINE, Cochrane Library, Embase, Scopus, and Web of Science) from January 2000 to November 2017 and in 41 recent reviews. Two investigators independently extracted and assessed study data using standardised forms. Additional unpublished data were obtained from trial authors. The primary endpoint 'any cardiac event' was a composite of cardiac death, non-fatal myocardial infarction (MI), unstable angina (UA), or heart failure (HF) hospitalisation. We performed a meta-analysis of relative risks (RRs) with 95% confidence intervals (CI) using the Mantel-Haenszel method. We included five RCT's with 3299 patients, of which 189 (5.7%) experienced any cardiac event on follow-up (weighted mean 4.1 years). Non-invasive CAD screening significantly reduced any cardiac event by 27% RR 0.73 (95% CI 0.55-0.97), P = 0.028, number needed to screen 56. This result was driven by important, albeit non-significant decreases in non-fatal MI RR 0.65 (95% CI 0.41-1.02), P = 0.062 and HF hospitalisation RR 0.61 (95% CI 0.33-1.10), P = 0.100. Non-invasive CAD screening did not significantly affect cardiac death RR 0.92 (95% CI 0.53-1.60), P = 0.77 and UA RR 0.73 (95% CI 0.41-1.31), P = 0.29. Compared with the standard care, non-invasive CAD screening reduced cardiac events by 27% in asymptomatic diabetic patients, largely through reductions in non-fatal MIs, and HF hospitalisations. The present results justify larger, appropriately powered trials to potentially revisit current recommendations.