title: Validation of the Charlson comorbidity index in patients undergoing revision total hip arthroplasty.
abstract: OBJECTIVE
  The Charlson comorbidity index (CCI) was developed to quantify the influence of comorbidities on survival. The age-related CCI respects patients' age as an additional risk factor. There are several studies available based on administrative data regarding functional outcome, implant survival, resource use and length of hospital stay in patients undergoing primary total hip arthroplasty (THA). To date, there is a lack of knowledge regarding the correlation of the CCI and the age-related CCI in case of revision total hip arthroplasty (RTHA).
  
  
  OBJECTIVE
  Our objective was to validate the influence of the CCI and age-related CCI in patients undergoing RTHA regarding complication rate, resource use implant survival and mortality rate.
  
  
  METHODS
  Between October 2007 and November 2012, 142 consecutive patients undergoing RTHA were included in this retrospective study. Routine clinical data were collected and analysed as anonymized aggregated data. In accordance to CCI and age-related CCI the rate of complications (internal medical and surgical complications), the length of hospital stay and the need for ICU treatment and the mortality rate was evaluated. Kaplan-Meier survivorship was used to determine implant survival.
  
  
  RESULTS
  Twenty-one patients (15%) had a low risk CCI, 59 patients (41%) a moderate risk CCI and 62 patients (44%) a high risk CCI. The mean follow-up was 27 months (range 24-70 months). In total, we recorded 57 complications (40%), of which 45 were surgical (79%) and 12 were internal medical complications (21%). Twenty-four patients (17%) had to undergo revision surgery. CCI and age-related CCI had no influence regarding implant survival. We recorded a significant influence of the age-related CCI in regard to the necessity of postoperative intensive care unit stay and the length of total hospital stay. Further we recorded a significant influence of the CCI and the age-related CCI regarding postoperative complications and internal complications, postoperative dislocation and the need for surgical revision.
  
  
  CONCLUSIONS
  In summary, we conclude that the CCI and the age-related CCI are strong predictors regarding complication rate in patients undergoing RTHA. In a short- to mid-term follow-up, no influence on implant survival is detectable.
authors.affiliation: Department for Orthopaedic und Trauma Surgery, Rheinische Friedrich-Wilhelms-University Bonn, Sigmund-Freud-Strasse 25, 53105, Bonn, Germany, Jan.Schmolders@ukb.uni-bonn.de.
authors.forename: Jan
authors.initials: J
authors.lastname: Schmolders
authors.forename: Max J
authors.initials: MJ
authors.lastname: Friedrich
authors.forename: Robert
authors.initials: R
authors.lastname: Michel
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Strauss
authors.forename: Matthias D
authors.initials: MD
authors.lastname: Wimmer
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Randau
authors.forename: Peter H
authors.initials: PH
authors.lastname: Pennekamp
authors.forename: Dieter C
authors.initials: DC
authors.lastname: Wirtz
authors.forename: Sascha
authors.initials: S
authors.lastname: Gravius
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000401:mortality; D015897:Comorbidity; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate