title: Revised cardiac risk index and postoperative morbidity after elective orthopaedic surgery: a prospective cohort study.
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.
authors.affiliation: Department of Medicine, Wolfson Institute for Biomedical Research, London, UK. g.ackland@ucl.ac.uk
authors.forename: G L
authors.initials: GL
authors.lastname: Ackland
authors.forename: S
authors.initials: S
authors.lastname: Harris
authors.forename: Y
authors.initials: Y
authors.lastname: Ziabari
authors.forename: M
authors.initials: M
authors.lastname: Grocott
authors.forename: M
authors.initials: M
authors.lastname: Mythen
mesh_terms: D000367:Age Factors; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008131:London / Q000453:epidemiology; D008171:Lung Diseases / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016459:Prosthesis-Related Infections / Q000453:epidemiology / Q000209:etiology; D012086:Reoperation / Q000009:adverse effects; D012606:Scotland / Q000453:epidemiology