Abstract
BACKGROUND: The revised cardiac risk index (RCRI) is associated strongly with increased cardiac ischaemic risk and perioperative death. Associations with non-cardiac morbidity in non-cardiac surgery have not been explored. In the elective orthopaedic surgical population, morbidity is common but preoperative predictors are unclear. We hypothesized that RCRI would identify individuals at increased risk of non-cardiac morbidity in this surgically homogenous population. METHODS: Five hundred and sixty patients undergoing elective primary (>90%) and revision hip and knee procedures were studied. A modified RCRI (mRCRI) score was calculated, weighting intermediate and low risk factors. The primary endpoint was the development of morbidity, collected prospectively using the Postoperative Morbidity Survey, on postoperative day (POD) 5. RESULTS: Morbidity on POD 5 was more frequent in patients with mRCRI ≥ 3 {relative risk 1.7, [95% confidence interval (CI): 1.4-2.1]; P<0.001}. Time to hospital discharge was delayed in patients with mRCRI score ≥ 3 (log-rank test, P=0.0002). Pulmonary (P<0.001), infectious (P=0.001), cardiovascular (P=0.0003), renal (P<0.0001), wound (P=0.02), and neurological (P=0.002) morbidities were more common in patients with mRCRI score ≥ 3. Pre/postoperative haematocrit, anaesthetic/analgesic technique, and postoperative temperature were similar across mRCRI groups. There were significant associations with hospital stay, as measured by the area under the receiver-operating characteristic curves for mRCRI 0.64 (95% CI: 0.58-0.70) and POSSUM 0.70 (95% CI: 0.63-0.75). CONCLUSIONS: mRCRI score ≥ 3 is associated with increased postoperative non-cardiac morbidity and prolonged hospital stay after elective orthopaedic procedures. mRCRI can contribute to objective risk stratification of postoperative morbidity.