Interdialytic weight gain and survival in hemodialysis patients: Effects of duration of ESRD and diabetes mellitus

Background. Medical mortality determinants in end-stage renal disease (ESRD ) patients treated with hemodialysis (HD) are well known. More recently, as sociations have been established between the dose of dialysis administered and patient survival. We showed in a prospective study that both dialyzer t ype and patient compliance with the dialysis prescription were independentl y associated with survival. Although several parameters of dialytic techniq ue and patient compliance are associated with differential survival in pati ents with ESRD treated with HD, the association of interdialytic weight gai n (IWG) with survival is unclear. No study has assessed the relationship be tween IWG and mortality in HD patients, controlled for multiple medical ris k factors. The aim of our study was to determine whether IWG was associated with survival in patients with ESRD treated with HD, controlling for multi ple medical and dialytic risk factors. Method's. We prospectively conducted an observational, longitudinal, multic enter study of 283 urban HD patients to determine the relationship of IWG w ith several dialytic parameters and patient survival. Medical risk factors such as demographic indices and comorbid conditions were assessed. We studi ed Kt/V, the protein catabolic rate (PCR), serum albumin and anthropometric measurements, behavioral compliance indices, dialyzer characteristics, and serum electrolyte concentrations, and correlated these with IWG. In additi on, the duration of dialysis was assessed in HD patients with and without d iabetes mellitus. Cox proportional hazards models assessed the relative mor tality risk of increased IWG, controlling for variations in medical comorbi dity and other mortality determinants. Results. The mean (+/-SD) age of our population was 54.6 +/- 14.1 years, an d the mean time they were treated with HD was 30.4 +/- 46.9 months. The mea n IWG was 1.54 +/- 0.71% dry wt/day. Correlations were found between increa sed IWG and younger age, and lower midarm circumference, and increased Kt/V , PCR, and serum potassium concentration. The mean follow-up period was 48. 9 +/- 10.6 months. An increase in IWG was associated with a significantly i ncreased relative mortality risk in diabetic ESRD patients treated with HD when variations in age, comorbidity, serum albumin concentration, and dialy zer type and site were controlled. There was, however, no association of in creased mortality risk with increased IWG in the larger population of patie nts without diabetes. In further analyses, the increased mortality risk ass ociated with increased IWG was found to be present only in patients with di abetes mellitus who had recently started HD therapy for ESRD. Conclusion. IWG is correlated with several nutritional and dialytic variabl es and with parameters that predict survival in HD patients. Increased IWG is independently associated with decreased survival of diabetic ESRD patien ts treated with HD, after adjusting for variation in other medical risk fac tors. The population of incident diabetic HD patients is particularly susce ptible to increased risk associated with increased IWG. The mechanisms unde rlying these results are obscure, but IWG might be associated with poorer s urvival in this population if it were linked to worsened hypertension, card iovascular stress, or poorer glycemic control. Interventions to improve com pliance with IWG in incident diabetic HD patients are warranted.