Dialysis Case Volume Associated With In-Hospital Mortality in Maintenance Dialysis Patients

Abstract

IntroductionAccumulating evidence suggests that a large hospital volume (HV) is associated with favorable outcomes in various diseases or surgical procedures. The aim of this study is to clarify the correlation of HV and dialysis case volume (DCV) with in-hospital death in patients on maintenance dialysis.MethodsThe study cohort was derived from the Diagnosis Procedure Combination database, a national inpatient database in Japan, from 2012 to 2014. We included 382,689 admissions of maintenance dialysis patients over the age of 20 years in the analysis. HV was defined as the mean number of daily hospitalized patients, and DCV was defined as the mean number of annually hospitalized patients on maintenance dialysis. The primary outcome was in-hospital all-cause mortality, evaluated using multivariable logistic regression models across the respective quartiles of HV and DCV.ResultsThe mean age of participants was 69 ± 12 years; 94% were receiving hemodialysis, and 21,182 patients (5.5%) died after hospitalization. In unadjusted models, larger HV and DCV were both associated with lower in-hospital mortality. However, this association remained significant only for DCV after adjustment for potential confounders, with multivariable-adjusted odds ratios of 0.82 (95% confidence interval [CI], 0.79–0.85), 0.76 (95% CI, 0.73–0.80), and 0.68 (95% CI, 0.65–0.72) for DCV 249 to 432, 433 to 713, and ≥714 (vs. ≤ 248) admissions per year, respectively. Multivariable subgroup analyses determined that this association was independent of age, sex, dialysis modality, Charlson Comorbidity Index, and emergency admission.ConclusionSelective admission to hospitals with a large DCV may improve outcomes of dialysis patients.

Burden of kidney disease on the discrepancy between reasons for hospital admission and death: An observational cohort study

“…A small proportion of patients with ESKD died after vascular access-associated admission. A higher proportion of patients with ESKD were admitted to hospitals with a higher HV and DCV [ 17 ].…”

“…To investigate whether HV factors affected the discrepancy between the reasons for hospital admission and death across the groups, we illustrated the Funnel plots [ 23 ] of the observed and expected range of the discrepancy rate of ICD-10 codes based on the Poisson distribution for HV representing mean admissions per day and DCV [ 17 ] representing mean annual dialysis admissions per year ( Fig 2 ). The rate of discrepancy was found to be independent of HV factors across the groups and remained high for CKD and ESKD patients even when these patients were treated in hospitals with a large HV or DCV.…”

“…Data were taken from the Diagnosis Procedure Combination (DPC) national inpatient database in Japan for the years 2012–2015 [ 14 , 16 , 17 ]. The DPC uses a case-mix classification system to ensure the transparency of hospital performance, which is linked with a payment system.…”

“…The ICD-10 codes N181, N182, N183, N184, and N185 that correspond to each CKD grade has yet to be recorded in the database. Patients with ESKD on maintenance hemodialysis or peritoneal dialysis were identified based on the code of patient care procedures: chronic maintenance hemodialysis with <4 hours per session, ≥4 hours and <5 hours per session, ≥5 hours per session, chronic maintenance hemodiafiltration, or continuous peritoneal dialysis [ 17 ]. Patients with incomplete information regarding patient characteristics at admission and those with a body mass index (BMI) under 15 kg/m 2 or over 50 kg/m 2 were excluded.…”

“…Other patient-level data included age, sex, and fiscal year of admission. The hospital-level variables were hospital volume (HV), which represents the mean daily number of hospitalized patients with and without ESKD, and dialysis case volume (DCV), which is the mean annual number of hospitalized patients who received maintenance dialysis [ 17 ].…”