To examine the effect of different stages of chronic kidney disease (CKD) on patients’ risk of post-operative mortality

Question 4 [25 marks]:

Objectives: To examine the effect of different stages of chronic kidney disease (CKD) on patients’ risk of post-operative mortality and complications following isolated coronary artery bypass grafting (CABG) in a large cohort of patients who had cardiac surgery.

Description: All patients who underwent isolated CABG in the cohort were reviewed, and their preoperative glomerular filtration rates (eGFR) were estimated using the Chronic Kidney Disease Epidemiology Collaboration creatinine equation.

The CKD stages were classified as follows: normal: eGFE ≥ 90 ml/min/1.73m² and not on dialysis, mild: eGFR 60-89 ml/min/1.73m² and not on dialysis, moderate: eGFR 30 - 59 ml/min/1.73m² and not on dialysis, severe: eGFR < 30 ml/min/1.73m² and not on dialysis; and dialysis dependent.

Analysis Method: The descriptive statistics for various post-operative outcomes were reported as percentages (see Table 2). The effect of CKD stages on each of the outcomes following isolated CABG were examined using multiple logistic regression method. In the multiple logistic regression analysis the CKD variable was adjusted for other 12 predictors (please see the list below the Table 3), i.e., there were 13 predictors in each of the regression models including CKD stages. However, the OR, 95% CI and p-value were reported only for CKD stages (see Table 3). Normal CKD stage was considered as the reference category in the multiple logistic regression analysis. Thus, the ORs in the Table 3 quantify the odds of various CKD stages (moderate to severe) as compared to normal CKD stage. Please see the Appendix for a brief description of post-operative mortality and complications.

Discuss the results in Tables 2 and 3 and make a summary conclusion followed by the impact of the findings. Your answer must have only the following three separate sections:

• Section 1: Summary (overall) discussion of descriptive statistics (presented in Table 2) of post-operative outcomes by CKD
• Section 2: Summary (overall) discussion of multiple logistic regression analysis results presented in Table
• Section 3: Make a brief summary conclusion about the effect of CKD on post-operative mortality and complications (see column 1 in Table 3 for the list of these variables) followed by the impact of the findings.