Use of propensity score in cost-effectiveness analysis using drug-eluting and bare metal stents

ABSTRACTBACKGROUNDStudies on the cost-effectiveness ratio of drug-eluting stents (DES) are rare. Our objective was to evaluate the results and compare costs (incremental cost-effectiveness ratio – ICER) per restenosis avoided between DES and bare metal stents (BMS) using the propensity score.METHODSTwo hundred and twenty consecutive patients were included in the study, of which 111 were treated with DES and 109 with BMS. The propensity score was used to adjust the effect of the intervention, by means of matching, stratification and weighing.RESULTSMost patients were male (67.7% vs. 66.9%; P = 0.53), with a mean age of 65.9 years. Patients treated with the DES had a higher rate of diabetes (54% vs. 17.4%; P < 0.001), three-vessel disease (18.9% vs. 10.1%; P = 0.029) and poor ventricular function (54.1% vs. 22%; P < 0.0001). The diameter of stents was 2.76 ± 0.35mm vs. 2.91 ± 0.47mm (P = 0.006) and the sum of the lengths of stents was 37.6 ± 23mm vs. 24.8 ± 15.8mm (P < 0.0001). Restenosis was observed on 6.3% vs. 12.8% of the patients (P = 0.099) and in 4.1% vs. 9.8% of the lesions (P = 0.048). There was an incremental cost of R$9,500.00 and the ICER was R$ 147,538.00 per restenosis avoided (above the World Health Organization threshold). However, when the propensity score was used, the variables that best classified patients for DES and had a maximum ICER of R$ 4,776.96 were age > 72 years, diabetes and lesions with diameter < 3.2mm and length > 18mm.CONCLUSIONSAlthough DES were not cost-effective in the overall population, the propensity score showed that in elderly patients, diabetics and patients with long lesions or small vessels, the use of DES was cost-effective