OBESITY IS NOT ASSOCIATED WITH INCREASED MORTALITY IN AUSTRALIA AND NEW ZEALAND PERITONEAL DIALYSIS PATIENTS

S MURTHY¹, S ULLAH², J BARBARA^1,3, G PASSARIS¹, S MCDONALD^2,4,5, R JUNEJA^1,3

¹ Flinders Medical Centre, Adelaide, South Australia; ²ANZDATA Registry, Adelaide, South Australia; ³Flinders University, Adelaide, South Australia; ⁴Royal Adelaide Hospital, Adelaide, South Australia; ⁵The University of Adelaide, Adelaide, South Australia

Aim: This study aimed to investigate the association of body mass index (BMI) with peritoneal dialysis outcomes in Australia and New Zealand patients.

Background: The association of BMI with peritoneal dialysis outcomes remains uncertain. There have been numerous studies with varied associations.

Methods: ANZDATA registry data for 10,364 incident peritoneal dialysis patients between 1 April 2002 and 31 March 2014 were analysed. Patients were assigned to 4 BMI categories: Underweight (<18.5), Normal (18.5 – 24.9), Overweight (25 – 29.9) and obese (≥30). A multivariate Cox model and competing risk analysis were performed to predict technique and patient survival.

Results: Of the 10,364 patients, almost 27% (n=2,806) were obese. Obesity was associated with a risk of technique failure (HR, 1.24; 95% CI, 1.16 – 1.32; P<0.001) but not with increased mortality (HR, 1.04; 95% CI, 0.96 – 1.13; P= 0.31). The overall technique failure rate (per 1000 person-years) showed a declining trend (P<0.004). Underweight status was strongly associated with increased mortality (HR, 1.32; 95% CI, 1.10 – 1.58; P < 0.01). For cardiovascular events, both overweight and obesity were strongly associated with increased mortality (HRs, 1.24 and 1.47; 95% CI, 1.12 to 1.39 and 1.32 to 1.64; P <0.001 respectively). Standard Cox proportional hazards and competing risk models showed almost similar results for patient survival.

Conclusions: Underweight status is associated with increased mortality for peritoneal dialysis patients. Obesity is not associated with increased mortality but continues to be associated with a risk of technique failure. The data also suggests a declining trend over the study duration in technique failure. Underweight patients need careful evaluation before commencement on peritoneal dialysis.