title: Validation of the SF-36 as a measure of postoperative recovery after colorectal surgery.
abstract: BACKGROUND
  Surgery is evolving, and new techniques are introduced to improve "recovery." Postoperative recovery is complex, and evaluating the effectiveness of surgical innovations requires assessment of patient-reported outcomes. The Short-Form-36 (SF-36), a generic health-related quality of life questionnaire, is the most commonly used instrument in this context. The objective of this study was to contribute evidence for the validity of the SF-36 as a metric of postoperative recovery.
  
  
  METHODS
  Data from 128 patients undergoing planned colorectal surgery at one university hospital between 2005 and 2010 were analyzed. In the absence of a gold standard, the responsiveness and construct validity (known groups and convergent) of the SF-36 were evaluated. Standardized response means were computed for the former and non-parametric tests were used to assess the statistical significance of the changes observed. Multiple linear regression was used to determine whether the SF-36 discriminates between patients with versus without complications and between laparoscopic and open surgery (known groups); correlations between the SF-36 and the 6-min walk test, a measure of functional walking capacity (convergent) was investigated with Spearman's rank correlation.
  
  
  RESULTS
  The SF-36 was sensitive to clinically important changes. Scores on six of eight domains and the physical component summary score deteriorated postoperatively (SRM 0.86 for the PCS, p < 0.01) and improved to baseline thereafter. Patients with complications had significantly lower scores on five SF-36 domains (with differences from -9 (-18, -1), p = 0.04 to -18 (-32, -2), p = 0.03), and scores on all subscales were lower than those in a healthy population (p < 0.01 to p = 0.04). The SF-36 did not differentiate between laparoscopic and open surgery. Physical functioning scores correlated with 6MWT distance at 1 and 2 months (Spearman's r = 0.31 and 0.36, p < 0.01).
  
  
  CONCLUSIONS
  The SF-36 is responsive to expected physiological changes in the postoperative period, demonstrates construct validity, and thus constitutes a valid measure of postoperative recovery after planned colorectal surgery. The SF-36 did not, however, discriminate between recovery after laparoscopic and open surgery.
authors.affiliation: Division of General Surgery, Steinberg-Bernstein Centre for Minimally Invasive Surgery and Innovation, McGill University Health Centre, 1650 Cedar Ave, L9.300, Montreal, QC, H3G 1A4, Canada, ioana.antonescu@mail.mcgill.ca.
authors.forename: Ioana
authors.initials: I
authors.lastname: Antonescu
authors.forename: Francesco
authors.initials: F
authors.lastname: Carli
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Mayo
authors.forename: Liane S
authors.initials: LS
authors.lastname: Feldman
mesh_terms: D000328:Adult; D000368:Aged; D003108:Colonic Diseases / Q000601:surgery*; D013505:Digestive System Surgical Procedures / Q000534:rehabilitation; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011788:Quality of Life; D012002:Rectal Diseases / Q000601:surgery*; D011795:Surveys and Questionnaires; D016138:Walking