title: Chronic kidney disease and postoperative morbidity after elective orthopedic surgery.
abstract: BACKGROUND
  Reduced estimated glomerular filtration rate (eGFR) is strongly associated with increased cardiovascular risk and all-cause mortality. Associations with morbidity in elective, moderate-risk noncardiac surgery have not been explored. We hypothesized that chronic kidney disease (CKD) would be associated with excess morbidity after elective, moderate-risk orthopedic surgery.
  
  
  METHODS
  Patients undergoing elective orthopedic joint replacement procedures were studied, representing a large proportion of global surgical procedures and characterized by highly homogeneous anesthetic and surgical practice. eGFR was calculated from routine creatinine measurements using the Modification of Diet in Renal Disease equation. CKD was defined as eGFR < 60 mL/min/1.73 m². Cardiac risk (Revised Cardiac Risk Index) and evidence-based, perioperative factors associated with perioperative morbidity (operative time, blood loss, perioperative temperature) were also recorded prospectively. The primary end point was postoperative morbidity, recorded prospectively using the postoperative morbidity survey. Morbidity differences were analyzed between patients with CKD and normal preoperative renal function (χ² test for trend) and presented as hazard ratio (HR) or odds ratio (OR) with 95% confidence intervals (95% CIs). The secondary end points were time to hospital discharge and time to become morbidity free (analyzed by log-rank test), both between and within CKD compared with normal renal function patients. Multiple regression analysis was performed to assess the association of CKD, perioperative factors with morbidity, and length of hospital stay.
  
  
  RESULTS
  Postoperative morbidity survey was recorded in 526 patients undergoing elective orthopedic surgery. CKD patients (n = 142; 27%) sustained excess morbidity on postoperative day 5 (OR 2.1 [95% CI: 1.2-3.7]; P < 0.0001). CKD patients took longer (HR 1.6 [95% CI: 1.2-1.9]) to become morbidity free (log-rank test, P < 0.0001). Time to hospital discharge was delayed by 4 days in CKD patients (HR 1.4 [95% CI: 1.2-1.7]; P = 0.0001; log-rank test). CKD patients sustained more pulmonary (OR 2.2 [95% CI:1.3-3.6]; P = 0.002), infectious (OR 1.7 [95% CI:1.1-2.7]; P = 0.01), cardiovascular (OR 2.4 [95% CI: 1.2-4.8]; P = 0.01), renal (OR 2.3 [95% CI:1.5-3.5]; P < 0.00,001), neurological (OR 4.3 [95% CI:1.3-17.7]; P = 0.005), and pain (OR 1.8 [95% CI:1.03-3.1]; P = 0.04) morbidities. Further stratification of CKD revealed preoperative eGFR ≤ 50 mL/min/1.73 m(2) to be associated with more frequent morbidity and longer hospital stay, independent of age. Multiple regression analysis identified CKD (P = 0.006) and congestive cardiac failure (P = 0.002) as preoperative factors associated with prolonged hospital stay.
  
  
  CONCLUSIONS
  A substantial minority of patients with CKD undergoing elective orthopedic procedures are at increased risk of prolonged morbidity and hospital stay. Preoperative eGFR may enhance perioperative risk stratification beyond traditional risk factors.
authors.affiliation: Department of Medicine, Wolfson Institute for Biomedical Research, University College London, UK. g.ackland@ucl.ac.uk
authors.forename: Gareth L
authors.initials: GL
authors.lastname: Ackland
authors.forename: Noeleen
authors.initials: N
authors.lastname: Moran
authors.forename: Steven
authors.initials: S
authors.lastname: Cone
authors.forename: Michael P W
authors.initials: MP
authors.lastname: Grocott
authors.forename: Michael G
authors.initials: MG
authors.lastname: Mythen
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement / Q000009:adverse effects* / Q000379:methods; D002318:Cardiovascular Diseases / Q000401:mortality; D003404:Creatinine / Q000378:metabolism; D017558:Elective Surgical Procedures; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000401:mortality*; D008297:Male; D009985:Orthopedics / Q000379:methods*; D011183:Postoperative Complications; D011446:Prospective Studies; D012306:Risk; D013696:Temperature; D013997:Time Factors
chemical_list: D003404:Creatinine