title: Response shift in quality of life after endoscopic sinus surgery for chronic rhinosinusitis.
abstract: OBJECTIVE
  Patient-reported measures are designed to detect a true change in outcome, but they are also subject to change from biases inherent to self-reporting: changing internal standards, changing priorities, and changing interpretations of a given instrument. These biases are collectively known as "response shifts" and can obscure true change after medical interventions.
  
  
  OBJECTIVE
  To determine the presence of response shifts in patients with chronic rhinosinusitis (CRS) after endoscopic sinus surgery.
  
  
  METHODS
  Multisite, prospective, observational cohort study conducted at academic tertiary care centers between February 2011 and May 2013. Study participants comprised a population-based sample of 514 adults (age ≥18 years) with CRS, who elected surgical intervention for continuing medically refractory symptoms.
  
  
  METHODS
  Endoscopic sinus surgery.
  
  
  METHODS
  Preoperative and postoperative data from the 22-item Sinonasal Outcome Test (SNOT-22) survey instrument was characterized using exploratory factor analysis. Subsequent longitudinal structural equation models were estimated to test structure, potential response shifts, and true change in the SNOT-22 scores.
  
  
  RESULTS
  A total of 339 participants (66.0%) provided survey evaluations at baseline and 6-month follow-up. Factor analysis of the SNOT-22 revealed 5 correlated, yet distinguishable, underlying factors. Endoscopic sinus surgery had a differential impact across these factors, with the largest effect size in rhinologic symptoms (mean [SD] SNOT-22 scores before and after surgery, 13.18 [5.11] and 7.37 [5.48], respectively; d = -1.13 [P < .001]) and extranasal rhinologic symptoms (8.31 [3.46] and 4.83 [3.68], respectively; d = -1.00 [P < .05]) (d is an effect size measure defined as the difference in means divided by the presurgery SD). Endoscopic sinus surgery had a smaller, yet significant, effect size on the remaining 3 factors: ear/facial symptoms (7.32 [4.6]) and 3.90 [4.07], respectively; d = -0.74 [P < .001]), psychological dysfunction (11.90 [7.21] and 6.50 [6.69], respectively; d = -0.75 [P < .05]), and sleep dysfunction (10.12 [5.59] and 5.88 [5.37], respectively; d = -0.76 [P < .001]). Participants were found to undergo recalibration, reprioritization, and reconceptualization of symptoms after intervention; however, the magnitude of these response shifts was small and not clinically significant.
  
  
  CONCLUSIONS
  The SNOT-22 measures 5 distinct factors, not a single construct. Reporting of individual subscale scores may improve sensitivity of this instrument in future studies. Participants undergoing endoscopic sinus surgery experience only clinically insignificant response shifts, validating assessment of change through use of presurgery and postsurgery SNOT-22 responses.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT01332136.
authors: Division of Rhinology and Sinus Surgery, Oregon Sinus Center, Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland.
authors: Adam S
authors: AS
authors: DeConde
authors: Department of Psychology, Portland State University, Portland, Oregon.
authors: Todd E
authors: TE
authors: Bodner
authors: Division of Rhinology and Sinus Surgery, Oregon Sinus Center, Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland.
authors: Jess C
authors: JC
authors: Mace
authors: Division of Rhinology and Sinus Surgery, Oregon Sinus Center, Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland.
authors: Timothy L
authors: TL
authors: Smith
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D004724:Endoscopy; D005163:Factor Analysis, Statistical; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D013517:Otorhinolaryngologic Surgical Procedures / Q000379:methods*; D017063:Outcome Assessment, Health Care / Q000592:standards; D011184:Postoperative Period; D011446:Prospective Studies; D011788:Quality of Life; D012220:Rhinitis / Q000601:surgery*; D057566:Self Report; D012852:Sinusitis / Q000601:surgery*