**7. Patients**

The study included 1200 patients undergoing coronary artery bypass grafing with arteries (internal mammar, radial, gastroepiploic) or inverted saphenal veins. The patients were randomised to receive Clopidogrel 75 mg daily or Aspirin 75 mg daily or Aspirin plus Clopidogrel 75mg daily one day after surgery and in the postoperative period for no less than 1 year.. The patients undergoing also venticular remodelling for aneurysms were not taken in our study.

The baseline characteristics were similar in the three arms of the study (Table 1). Overall, the study populations were similar to those of previous trials on antiagregants.


**Table 1.** Baseline characteristics

**6.1. Primary and secondary endpoints**

calculation

296 Artery Bypass

**7. Patients**

used for the estimation of the medium term prognosis were:

The looked at all-cause mortality and major cardiac events, namely cardiac mortality, myo‐ cardial infarction or need for target lesion revascularization. The most important endpoints

The primary endpoint (efficacy endpoint) was a composite outcome cluster of 30-day mortal‐ ity, myocardial infarction, in-hospital and at 1 year occurrence of graft occlusion (efficacy endpoints), total hospital stay and immobilization (measured in days), Intensive Care Unit length of stay and cost, quality of life. Quality of life was appreciated using a scale from one

The secondary endpoints at 30 days looked at in-hospital major peripheral or bleeding complications (including surgical bleeding complications, transfusion of at least two units of blood, intracranial bleeding, retroperitoneal bleeding, overt hemorrhage), neutropenia (<1.5 x 109 per litre), thrombocytopenia (<100 x 109 per litre), early discontinuation of the study drug due to a non-cardiac adverse event (including death of non-cardiac origin) (safety endpoint).

The data collected represented the fields of a database in the Visual Fox Pro computer program. Data were processed by means of computers, using the Excel, EpiInfo, Systat and SPSS programs for multivariate regression analysis and relative risk and correlation coefficient

No confirmatory statistical hypothesis was pre-specified, but a detailed analysis plan was defined before the database was locked. This analysis plan was based on generating risk ratios and CIs (CI=confidence index) for the pairwise comparisons of primary interest. These comparisons were presented with the two - sided 95% CI of the relative risk and with normal p values. For the primary endpoints Kaplan-Meier curves were constructed and log-rank tests were done. For each endpoint, a two-sided 95% CI was also calculated and an overall Chi

The frequency of the primary efficacy plus safety endpoint for the Aspirin group as a reference group was 17,7%. On the basis of phase-II studies we assumed that the experimental groups with Clopidogrel and Aspirin plus Clopidogrel would result in better, or at least similar outcomes when compared with standard treatment. The sample size and power calculations were therefore based on non-inferiority of the experimental group versus the reference group. The study has 80% power to exclude, with 95% confidence (one-sided), a 1% higher rate of the primary endpoints compared with the reference group, provided the point estimate in the experimental treatment group was 1,7% lower for the efficacy endpoint and 2% lower for the

The study included 1200 patients undergoing coronary artery bypass grafing with arteries (internal mammar, radial, gastroepiploic) or inverted saphenal veins. The patients were

square test, comparing the three treatment groups was done [19, 21, 25].

efficacy and safety endpoint. [2-11, 13-18, 22]

to ten calculated on the base of a questionnaire filled by the patients at each visit

The medications used chronically by the patients at the time of randomization were similar in the Aspirin, Clopidogrel and Aspirin plus Clopidogrel treatment arms and are are listed in Table 2


**•** Prediction variables :

**◦** patient ID Data

**•** • Outcomes variables:

**◦** death and its causes.

**◦** preoperative diagnosis

**◦** type of surgical intervention

intraoperative complications

following coronary artery surgery.

**•** parameters related to the type of the treatment

**◦** number of bleeding episodes and cost per patient

**◦** cost of the treatment for each patient

**◦** global cost/ patient

**◦** ICU duration and complications occured

**◦** presence and type of postoperative complications

using different tests depending on the type of variables:

**◦** for qualitative variables: CHI square test or Fischer exact test

correlation as analysis of simple linear and multivariate regression

**•** Relative Risk calculation and the 95% confidence limits for treatment groups

clopidogrel in CABG was done taking into account the following parameters:

**◦** surgical risk (calculated using a scale from 1 to 10 taking into account different preoper‐ ative parameters: age, co-morbidities, severity of cardiac lesions (NYHA class), type and

The Antiagregant Treatment After Coronary Artery Surgery Depending on Cost – Benefit Report

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**◦** specific variables related to the surgical performance: duration of surgical intervention,

The statistical analysis was performed using the SYSTAT and SPSS programmes for:

**•** Measurement of the power of association between the prediction variables and outcomes

**◦** for quantitative variables: T test (Student test), ANOVA test or U test depending on samples volumes and Kruskal Wallis nonparametric tests or other methods of statistical

**•** Cost-benefit ratio calculation for using different antiplatelets agents after coronary artery bypass grafting. It was determined using a special programme, which used the data from the database and different economic data from specialized departments from our Institute, in order to perform the assessment of the efficiency of different antiplatelet therapies

The calculation of the cost-benefit ratio for each type of treatment and for routinely use

**◦** number of supplementary echographic and endoscopic examinations per patient

duration of surgical intervention, associated risk factors)

**Table 2.** Number of patients who received concomitant medications during stay in hospital

61,46% of patients received Aspirin before surgery in group A, respectively 63,84% in group B and 65,17% in group C.

The primary efficacy and efficacy plus safety endpoints and their individual components in the treatment groups are shown in Table 3.

The clinical diagnosis at the time of randomization was similar in the three treated arms of the study:

