Impact of Obesity on Modality Longevity, Residual Kidney Function, Peritonitis, and Survival Among Incident Peritoneal Dialysis Patients

Abstract

Background: The prevalence of severe obesity, often considered a contraindication to peritoneal dialysis (PD), has increased over time. However, mortality has decreased more rapidly in the PD population than the hemodialysis (HD) population in the United States. The association between obesity and clinical outcomes among patients with end-stage kidney disease remains unclear in the current era.

Study design: Historical cohort study.

Setting & participants: 15,573 incident PD patients from a large US dialysis organization (2007-2011).

Predictor: Body mass index (BMI).

Outcomes: Modality longevity, residual renal creatinine clearance, peritonitis, and survival.

Results: Higher BMI was significantly associated with shorter time to transfer to HD therapy (P for trend < 0.001), longer time to kidney transplantation (P for trend < 0.001), and, with borderline significance, more frequent peritonitis-related hospitalization (P for trend = 0.05). Compared with lean patients, obese patients had faster declines in residual kidney function (P for trend < 0.001) and consistently achieved lower total Kt/V over time (P for trend < 0.001) despite greater increases in dialysis Kt/V (P for trend < 0.001). There was a U-shaped association between BMI and mortality, with the greatest survival associated with the BMI range of 30 to < 35kg/m² in the case-mix adjusted model. Compared with matched HD patients, PD patients had lower mortality in the BMI categories of < 25 and 25 to < 35kg/m² and had equivalent survival in the BMI category ≥ 35kg/m² (P for interaction = 0.001 [vs < 25 kg/m²]). This attenuation in survival difference among patients with severe obesity was observed only in patients with diabetes, but not those without diabetes.

Limitations: Inability to evaluate causal associations. Potential indication bias.

Conclusions: Whereas obese PD patients had higher risk for complications than nonobese PD patients, their survival was no worse than matched HD patients.

Keywords: Peritoneal dialysis (PD); creatinine clearance (CL(cr)); diabetes; dialysis modality; end-stage renal disease (ESRD); hemodialysis (HD); kidney transplantation; mortality; obesity; obesity paradox; peritonitis; renal replacement therapy (RRT); residual kidney function (RKF); survival advantage; technical failure; technical survival.