Thirteen studies were included in the review (10,447 patients): eight RCTs (5,797 patients) and five observational studies (4,650 patients). Study sample size ranged from 175 to 3,006. Follow-up ranged from 2.1 years to 5.8 years. All RCTs were evaluated as having adequate allocation, randomisation, baseline comparability of groups and intention-treat analysis. Seven RCTs reported that the outcome had been measured blindly but did not report that patients or caregivers had been blinded to the intervention. Percentage loss to follow-up ranged from 0% to 29% (where reported). All observational studies received the highest quality rating (A) for six of the eight domains measured; generally lower scores (range A to D) were given for assessment of the outcome and adequacy of follow-up.
RCTs: There were statistically significant lower odds of target lesion revascularisation (OR 0.48, 95% CI 0.37 to 0.61; seven trials) and major adverse cardiac events (OR 0.67, 95% CI 0.56 to 0.79; seven trials) with use of drug-eluting versus bare-metal stents. There was no evidence of significant statistical heterogeneity for target lesion revascularisation (Ι²=31.5%) and major adverse cardiac events (Ι²=17.8%).
No statistically significant differences were identified between drug-eluting stents and bare-metal stents for mortality, stent thrombosis and recurrent myocardial infraction. Significant heterogeneity was found for recurrent myocardial infarction.
Sensitivity analyses for all outcomes (excluding the largest RCT and then a trial with 29% loss to follow-up) yielded similar findings. Stratified analyses (by type of drug-eluting stent) revealed larger increases in all outcomes (except mortality) with sirolimus versus paclitaxel-eluting stents.
Observational studies: There were statistically significant lower odds of mortality (OR 0.65, 95% CI 0.53 to 0.80; four studies) and significantly higher odds for stent thrombosis (OR 1.62, 95% CI 1.18 to 2.21; five studies) were found with use of drug-eluting versus bare-metal stents. No statistical heterogeneity was indicated in either meta-analysis (Ι²=0%).
No statistically significant differences between drug-eluting stents and bare-metal stents were found for target lesion revascularisation and recurrent myocardial infarction. Statistically significant heterogeneity was identified for both outcomes.
Subgroup analyses revealed comparable results between sirolimus and paclitaxel-eluting stent registries for all of the outcomes except lower incidence of recurrent myocardial infarction in studies that used sirolimus-eluting stents.
Additional findings: All findings remained unchanged when meta-analyses were re-performed using fixed-effect models. Asymmetry in funnel plots suggested possible publication bias for target lesion revascularisation, mortality and myocardial infarction.