POSTOPERATIVE OUTCOMES IN CHRONIC DIALYSIS PATIENTS: A META‐ANALYSIS OF 42 STUDIES AND 78,805 PATIENTS

Abstract

Background: Chronic kidney disease is an independent risk factor for postoperative mortality, with an effect similar to that of diabetes mellitus or ischemic heart disease. However, the prognostic significance of dialysis‐dependence chronic kidney disease on perioperative outcomes, and its interaction with comorbid conditions is unclear. Aim: The aim of this study was to estimate the excess risk of postoperative mortality in patients receiving chronic dialysis undergoing elective non‐transplant surgery compared to those with normal kidney function, and to examine the influence on comorbidities on mortality risk. Methods: Two authors independently performed a systematic review of studies published up to 2018 was conducted using MEDLINE, EMBASE, DARE, CDSR, NICE, NIHR HTA databases. Eligible studies reported postoperative outcomes in patients on chronic dialysis and patients with normal kidney function undergoing major non‐transplant surgery. Non‐dialysis chronic kidney disease patients were excluded. Risk of bias was assessed using the Newcastle‐Ottawa Scale. Mortality risk estimates over all studies and according to surgical discipline were obtained using random effects meta‐analysis Meta‐regression analysis was performed to explore heterogeneity and assess associations of mortality with age, and comorbidities including ischemic heart disease and diabetes mellitus. (PROSPERO CRD42017076565) Results: Forty‐two studies involving 78,805 chronic dialysis and 9,984,469 non‐dialysis patients undergoing orthopaedic, vascular, cardiothoracic, general and urological procedures were included. Cohort selection and outcome ascertainment were of good quality, but comparability was poor. Absolute mortality rate varied from 0%‐8·9% in chronic dialysis patients and 0%‐3·9% in patients with normal kidney function across surgical disciplines. Patients on dialysis had a greatly increased postoperative mortality risk compared to patients with normal kidney function following all types of elective surgery (odds ratio [OR] 5·70, 95% CI 4·63 – 7·01). Adjustment for age and comorbidity attenuated this risk (OR 3·13, 95% CI 2·91 ‐ 3·34 I 290%). There was an inverse linear relationship between excess mortality risk and study‐level mean age (slope ‐0·06; P = 0·001), diabetes prevalence (slope ‐0·02; p = 0·001) and ischemic heart disease (slope ‐0·01; p = 0·049). Conclusions: Patients on chronic dialysis have a greatly increased postoperative mortality risk following elective surgery across all surgical disciplines, with the highest excess risk observed in those without other comorbidities. A comprehensive perioperative risk assessment and risk mitigation is required in patients on chronic dialysis.