title: Predicting 90-day mortality after bariatric surgery: an independent, external validation of the OS-MRS prognostic risk score.
abstract: BACKGROUND
  The Obesity Surgery Mortality Risk Score (OS-MRS) was developed using data from 1995 to 2004; it has yet to be validated for more recent patients in integrated delivery system settings. The objective of this study was to validate the OS-MRS using data from electronic health records in a distributed data network.
  
  
  METHODS
  We conducted a retrospective cohort study of 3,817 adults who underwent an open (21.4%) or laparoscopic (78.6%) gastric bypass surgery between 2005 and 2007 in the Scalable Partnering Network. Our main outcome was all-cause mortality during the 90 days after surgery. We scored patients' risk of mortality by adding characteristics according to the OS-MRS (i.e., 1 point for each predictor).
  
  
  RESULTS
  Sixteen of 3,817 (0.42/100; 95% CI, .24-.68) patients died within 90 days. The OS-MRS discriminated low-risk and high-risk patients effectively: low-risk (2 of 1,654 patients; .12 deaths/100 patients), intermediate-risk (10 of 2,008 patients; .50 deaths/100 patients), and high-risk (4 of 155 patients; 2.58 deaths/100 patients). High-risk patients were 21.3 times more likely to die in the first 90 days after surgery than low-risk patients (risk ratio = 21.3; 95% CI, 3.9-115.6).
  
  
  CONCLUSIONS
  In these 10 U.S. healthcare delivery systems, the OS-MRS appears valid-albeit with the caveat that we observed a small number of deaths. The OS-MRS appears useful for identifying the small fraction of patients at high risk for 90-day mortality after open and laparoscopic RYGB.
authors.affiliation: Group Health Research Institute, Seattle, Washington. Electronic address: arterburn.d@ghc.org.
authors.forename: David
authors.initials: D
authors.lastname: Arterburn
authors.affiliation: Kaiser Permanente Center for Health Research, Portland, Oregon.
authors.forename: Eric S
authors.initials: ES
authors.lastname: Johnson
authors.affiliation: Kaiser Permanente Georgia Center for Health Research Southeast, Atlanta, Georgia.
authors.forename: Melissa G
authors.initials: MG
authors.lastname: Butler
authors.affiliation: The Permanente Medical Group, Kaiser Permanente Northern California, San Francisco, California.
authors.forename: David
authors.initials: D
authors.lastname: Fisher
authors.affiliation: Kaiser Permanente Colorado Institute for Health Research, Denver, Colorado; University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Bayliss
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D005260:Female; D015390:Gastric Bypass / Q000401:mortality* / Q000706:statistics & numerical data; D006801:Humans; D010535:Laparoscopy / Q000401:mortality / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000401:mortality* / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D055815:Young Adult
keywords: Bariatric surgery; Gastric bypass; Mortality; Obesity; Prognostic risk score