Creatinine index: a retrospective cohort study in an urban Australian dialysis context.

Abstract

This study aimed to described the relationship between the CI and mortality in an Australian context. Maintenance haemodialysis is a catabolic state associated with a significant decrease in lean body mass (LBM) and protein energy wasting. LBM can be derived or estimated from creatinine kinetic modelling, specifically the creatinine index (CI). This has been demonstrated in cohort studies to predict mortality. One hundred seventy-nine patients undergoing haemodialysis in 2015 were included in this cohort. They were followed for 5 years with pertinent clinical data collected to calculate the CI as of December 2015. For analysis, patients were split into a high and low CI group based on the median (18.32 mg/kg/day). The primary outcome of interest was all-cause mortality, and secondary outcomes included myocardial infarction, stroke and transplantation. During follow-up, 69 (76.7%) patients in the low CI group and 28 (31.5%) patients in the high CI group died (P < 0.001). The relative risk (RR) of mortality within the low compared with the high CI group was 2.43 (95% confidence interval, 1.75-3.38). Fully adjusted Cox proportional hazards modelling demonstrated a hazard ratio (HR) of 0.498 (95% CI, 0.292-0.848) for survival in the high CI group. Lower CI was associated with increased risk of stroke (RR, 5.43 [95% CI, 1.24-23.84]), whereas transplant was more likely in the high CI group (RR, 6.4 [95% confidence interval, 1.96-20.88]). In a single-centre Australian haemodialysis cohort, the CI was strongly associated with mortality and stroke risk. The CI is an accurate and simple method to identify patients with low LBM at risk for significant morbidity and mortality.