SUN-188 PATIENT MORTALITY RISK FOR PERITONEAL DIALYSIS (PD) VERSUS FACILITY HEMODIALYSIS (HD) BY DIABETES MELLITUS STATUS OVER 1997-2017 IN THE AUSTRALIAN AND NEW ZEALAND DIALYSIS POPULATION

Abstract

Older literature suggests that mortality risk in patients with diabetes mellitus is higher on PD compared to HD. However, more recent literature from numerous health jurisdictions suggest that the overall mortality risk on PD is improving compared to that on HD (e.g. Sci Rep. 2019 Apr 11;9(1):5905). This may invalidate the findings in these older studies showing higher mortality with PD in diabetic patients. Here, we directly compare survival on PD versus facility HD by diabetes mellitus status (Type 1 or 2 vs. none) across different eras of the recent past. We studied all adult patients commencing renal replacement therapy in Australia and New Zealand in the 20 years prior 31-December-2017 using the Australia and New Zealand Dialysis and Transplant Registry (ANZDATA). We looked for the effect of PD versus facility HD on mortality risk by diabetic status across different eras of dialysis inception. We used Cox proportional hazards regression, adjusting for time-varying co-morbidity, demographics, late referral, primary renal disease, eGFR at dialysis inception, and initial treating center as a shared frailty. For the main analysis, we used an as-treated framework with time-varying modality and a 90-day lag for the attribution of death to modality. We performed a sensitivity analysis using an intention-to-treat framework with modality assigned at 90 days post-dialysis inception and no lag for the attribution of death. Given the non-proportional hazards for mortality between PD and HD, we repeated the analyses using eras of different lengths (4 x 5-year intervals, 3 x 7-year ones, 2 x 10-year ones). We censored patients at the end of each era to ensure the same maximum duration of follow-up within each era. The study cohort contained a maximum of 52,103 subjects with 19,667 deaths over 140,183 patient-years. 61% were males, median (IQR) age was 62 (22), 46.6% had diabetes mellitus. In those with diabetes mellitus, survival on PD was associated with worse survival compared to facility HD in the cohorts before 2013, but is associated with similar survival in cohorts initiating dialysis thereafter (e.g. hazard ratio for PD versus HD in those with diabetes mellitus starting 2013-2017 is 1.01, 95% confidence intervals 0.91 to 1.13). Increasing the length of the era and therefore duration of follow-up in each era did not abrogate improvement in mortality risk on PD relative to HD over time. The sensitivity analysis with the intention to treat framework did not meaningfully change estimates. Our study indicates that, despite increased comorbidity, survival outcomes on PD relative to facility HD are improving with time. This is the case also for patients with diabetes mellitus. Compared to previously, the survival of such patients is not meaningfully different on PD versus facility HD at the current time. Our analyses have potential for residual confounding from the limited collection of co-morbidity, and lack of socioeconomic, medication and biochemical data in analyses. The results of our study may be due to improved pre-dialysis care, patient selection (eg dialysis modality selection and dialysis versus conservative care in the elderly), improvements in general care of patient co-morbidities and advances in dialysis technology and practice.