#3559 THE IMPACT OF OBESITY ON CLINICAL OUTCOMES IN VARIOUS LEVELS OF CO-MORBIDITY OF NON-DIALYSIS CHRONIC KIDNEY DISEASE PATIENTS

Background and Aims: Obesity is a major issue with an estimated prevalence of 1.9 billion adults worldwide. Obesity is an important risk factor for premature death and the development of non-communicable diseases such as diabetes mellitus (DM), heart diseases, and chronic kidney disease (CKD). However, mounting evidence in the literature describes a reverse association whereby obesity may have a protective effect on mortality; this is sometimes referred to as the “obesity paradox”. Several reports question the concept of obesity paradox claiming methodology flaws such as collider stratification bias. In this study, we aimed to examine the effects of obesity on the combined outcomes of all-cause mortality (ACM) and renal replacement therapy (RRT) incidence in a cohort of patients with non-dialysis dependent CKD (NDDCKD) by correcting for major risk factors to reduce the risk of bias. Method: This retrospective study was undertaken on all patients with a documented body mass index (BMI) in the Salford Kidney Study database from October 2002 until December 2016. Patients were grouped according to their BMI into normal weight [BMI 18.5-24.9 kg/m2], overweight [BMI 25- 29.9 kg/m2 and obese [BMI>30 kg/m2]. Patients were also grouped according to their level of co-morbidity into 4 groups: group 1 had CKD only; group 2 had CKD and heart failure (HF); group 3 had CKD and DM; and group 4 had CKD, DM, and HF. Univariate Cox regression as well as three stepwise models of multivariate analysis were performed to study the strength of association between BMI categories and combined outcomes (incidence of RRT and ACM) across the 4 groups of different clusters of co-morbidity. Results: A total of 2416 patients were included in the analysis. Themedian age of the cohort was 67.3 years [IQR 55.9-75.6], 61.8% were male, and 96.4% were of white ethnicity. The median BMI was 28.1 kg/m2 [IQR 24.7-32.6] and the median estimated glomerular filtration rate (eGFR) was 30.7 ml/min/1.73m2 [IQR 20.4-43.5]. At baseline, patients with increasing level of co-morbidity tended to be older with higher prevalence of hypertension (HTN), angina, myocardial infarction (MI), and stroke with lower baseline eGFR. The risk of combined outcomes followed the same trend in the three BMI groups, risk is higher with higher index of co-morbidity (p