ABC | Volume 115, Nº1, July 2020

Original Article Pessoa et al. Cost-effectiveness comparison between drug-eluting stents and bare-metal stents Arq Bras Cardiol. 2020; 115(1):80-89 Statistical Analysis Numerical data were expressed as measures of central tendency and dispersion (mean, standard deviation, median, and interquartile range). Categorical data were expressed as frequencies (n) and percentages (%). Numerical variables with non-normal distribution (normality hypothesis rejected by the Shapiro-Wilk test) were analyzed using nonparametric tests. Numerical and categorical variables were compared considering the use of DES or BMS. Student’s t test for independent samples or the Mann-Whitney (nonparametric) test were used for the numerical variables, whereas the chi- square test or Fisher’s exact test were used for the categorical variables. The statistical analysis was performed using SAS System, version 6.11 (SAS Institute, Inc, Cary, North Carolina). The level of significance was set at 5% for all analyses.  The association of the variables under study with ISR was determined by univariate and multivariate analyses, according to the independent predictors identified by the forward stepwise binary logistic regression analysis. A Kaplan-Meier curve was used to analyze differences in ISR-free survival between the 2 groups, which were compared by the log-rank test. A decision tree model using TreeAge Pro Healthcare, version 2010 (TreeAge Software, Inc., Williamstown, MA, USA), was developed for cost analysis. A multivariable probabilistic sensitivity analysis was conducted with the variables with the greatest impact on the model in order to test the robustness of the result. Results Of 231 patients initially included in the study, 16 (6.9%) were lost after randomization. In the BMS group (n=154), 141 (91.5%) patients completed 1 year of follow-up, with 3 (2.1%) deaths: 2 from cardiac causes and 1 from stroke. In the DES group (n=77), 74 (96.1%) patients completed 1 year of follow- up, with 1 (1.4%) death from cardiac causes. During follow-up, invasive stratification was indicated after the onset of typical angina or after functional assessment suggestive of ischemia. In the BMS group, 32 (23.2%) patients were stratified with a second catheterization: 14 (10.1%) with ISR, 3 with new obstructive lesions, and 15 without obstructive lesions. Of 14 ISR cases, 4 were treated clinically: 1 patient had moderate restenosis associated with the development of a new lesion in another artery (treated with BMS implantation), and 3 patients had a diffuse, occlusive lesion that did not affect the anterior descending artery and were treated conservatively. Of the 10 remaining ISR cases, 5 were treated with DES implantation, 1 was treated with implantation of another BMS, 1 underwent coronary artery bypass grafting (CABG), and 3 underwent balloon angioplasty. Of the 3 patients treated with balloon angioplasty, 1 underwent a second PCI with DES implantation. In the DES group, 14 (18.9%) patients repeated catheterization: 1 with ISR (treated with implantation of another DES), 1 with a new lesion in another vessel (treated with BMS implantation), and 12 without obstructive lesions. Figure 1 – CABG:coronary artery by-pass graft; PCI-BMS:percutaneous coronary intervention witn bare metal stent; PCI-DES: percutaneous coronary intervention with drug elution stent. Source: Polanczyk et al(2007) 3 82