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INTRODUCTION: The Revised Cardiac Risk Index (RCRI) is a six-parameter model that is commonly used in assessing individual 30-day perioperative cardiovascular risk before general surgery, but its use in patients on chronic kidney replacement therapy (KRT) is unvalidated. This study aimed to externally validate RCRI in this patient group over a 15-year period. METHODS: Data linkage was used between the the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry and jurisdictional hospital admisisons data across Australia and New Zealand to identify all incident and prevalent patients on chronic KRT between 2000 and 2015 who underwent elective abdominal surgery. Chronic KRT was categorised as haemodialysis (HD), peritoneal dialysis (PD), home haemodialysis (HHD) and kidney transplant. The outcome of interest was major adverse cardiovascular event (MACE) which was defined as nonfatal myocardial infarction, nonfatal stroke, non-fatal cardiac arrest and cardiovascular mortality at 30 days. Logistic regression was used with the RCRI score included as a continuous variable to estimate discrimination by area under the receiver operating curve (AUROC). Calibration was evaluated using a calibration plot. Clinical utility was assessed using a decision curve analysis to determine the net benefit. RESULTS: A total of 5094 elective surgeries were undertaken, and MACE occurred in 153 individuals (3.0%). Overall, RCRI had poor discrimination in patients on chronic KRT undergoing elective surgery (AUROC 0.67), particularly in patients aged greater than 65 years (AUROC 0.591). A calibration plot showed that RCRI overestimated risk of MACE. The expected-to-observed outcome ratio was 6.0, 5.1 and 2.5 for those with RCRI scores of 1, 2 and ≥ 3, respectively. Discrimination was moderate in patients under 65 years and in kidney transplant recipients, with AUROC values of 0.740 and 0.718, respectively. Overestimation was common but less so for kidney transplant recipients. Decision curve analysis showed that there was no net benefit of using the tool in neither the overall cohort nor patients under 65 years, but a slight benefit associated with threshold probability > 5.5% in kidney transplant recipients. CONCLUSIONS: The RCRI tool performed poorly and overestimated risk in patients on chronic dialysis, potentially misinforming patients and clinicians about the risk of elective surgery. Further research is needed to define a more comprehensive means of estimating risk in this unique population.
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Peritoneal dialysis (PD) patients who undergo gastroendoscopy and colonoscopy are at increased risk of peritoneal dialysis-associated peritonitis (PD peritonitis) following the procedure (defined as occurring within 7 days of intervention). As per current International Society for PD (ISPD) guidelines, antibiotic prophylaxis is currently recommended pre-colonoscopy in PD patients given the risk of post-colonoscopy PD peritonitis. The risk of PD peritonitis in patients undergoing capsule endoscopy (CE) is unknown. This binational data-linkage study between the Australia and New Zealand Dialysis and Transplant Registry and all hospital admission data sets in Australia and New Zealand evaluated all patients with PD who underwent CE between 2006 and 2015. The objective of the study was to assess the risk of PD peritonitis in patients undergoing CE. Descriptive statistics were used to describe patient characteristics and clinical outcomes. Overall, 23 patients with PD underwent CE. Twelve patients underwent CE alone (i.e. no other concomitant procedures) and none of these patients experienced an episode of PD peritonitis. The remaining 11 patients underwent CE and other invasive endoscopic/abdominal surgical procedures, of whom 2 suffered PD peritonitis. CE is likely a relatively safe procedure in PD patients. PD patients undergoing CE may not require prior antibiotic prophylaxis. Given their relative safety, CE may be an appealing diagnostic tool in a select group of PD patients for the investigation of gastrointestinal disease.