A Cross-Sectional Study: Progression into Renal Replacement Therapy in Post Coronary Bypass Artery Graft Surgery Patients with Varying Pre-Operative Serum Creatinine Levels

Objective: To evaluate the likelihood of progression to renal replacement therapy (RRT) in patients with isolated coronary artery bypass graft (CABG) surgery with different serum levels of creatinine. Methods: This is a cross sectional study whereby patients included is those who had isolated CABG from 1 st January 2015 to 31 st December 2016. The patients are allocated into 3 different groups according to their serum creatinine level; <120mol/L, 120-200 mol/L, >200 mol/L. Baseline characteristics were also measured. Patients who have end stage renal disease (ESRD) or requiring dialysis pre-operation were excluded in the study. The primary outcome measured is the use of renal replacement therapy (RRT) post CABG. Sub analysis of the RRT group is also done to look at the proportions of Continuous Veno-venous Hemofiltration (CVVH) and Hemodialysis (HD) chosen. Secondary outcomes measured include mortality post CABG, length of intensive care unit (ICU) stay and total length of hospital stay. Results: Total of 2313 patients was included in the study. Baseline characteristic were measured. The mean age was 59.7 years old with majority of the patients are male (83.7%). Amongst the 3 groups of serum creatinine level, hypertension and diabetes have the highest proportion in the >200 mol/L creatinine group (94.8% and 84.4%) respectively. The rest of the measured baseline characteristic including cholesterol, chronic obstructive pulmonary disease, cross-clamp time and cardiopulmonary bypass time (CPB) were similar. The proportion of patients receiving RRT were highest (48.1% P<0.001) in the >200 mol/L creatinine group. In the 120-200 mol/L creatinine group (10.4% P<0.001) received RRT while in the <120mol/L creatinine group, (1.7% P<0.001) of the patients received RRT. For the total RRT patients, CVVH modality (3.7%) was used more than HD modality (1.8%). Mortality was highest (11.4% P<0.001) in the >200 mol/L creatinine group. Mortality in the 120-200 mol/L creatinine group and <120mol/L creatinine group were (6.4% and 2.1%, P<0.001) respectively. Length of ICU stay and total of length of hospital stay were similar. Conclusion: This study shows that patients who have renal impairment preoperatively are more likely to require RRT post CABG and it appears that the more deranged the creatinine level, the greater the likelihood will be. This indicates that aggressive measures at optimizing patients preoperatively is paramount.