title: Investigating minimal clinically important difference for Constant score in patients undergoing rotator cuff surgery.
abstract: BACKGROUND
  The minimal clinically important difference (MCID) is increasingly used to evaluate treatment effectiveness. The MCID for the Constant score has not been previously reported.
  
  
  METHODS
  A prospectively collected cohort of 802 consecutive shoulders with arthroscopically treated partial- or full-thickness rotator cuff tears was analyzed. The Constant score was measured preoperatively and at 3 months and 1 year postoperatively. At follow-up visits, the patients were asked a simple 2-stage question: Is the shoulder better or worse after the operation compared with the preoperative state? This single 2-level question was used as an indicator of patient satisfaction and as an anchor to calculate the MCID for the Constant score.
  
  
  RESULTS
  At 1 year, 781 (97.4%) patients (474 men, 307 women) were available for follow-up. The preoperative Constant score was 53.1 (SD 17.2) in all patients, 56.2 (SD 17.4) in male patients, and 48.2 (SD 15.6) in female patients. Postoperatively at 3 months, the scores were 61.7 (SD 16.4) in all patients, 65.1 (SD 16.1) in male patients, and 56.8 (SD 15.5) in female patients. At 1 year, the scores were 75.9 (SD 15.2) in all patients, 79.0 (SD 14.9) in male patients, and 71.0 (SD 14.3) in female patients. At 3 months postoperatively, 92.2% of male patients and 87.2% of female patients were satisfied with the outcome (P = .027); at 1 year, the satisfaction was 93.2% and 89.5%, respectively (P = .067). Five different statistical approaches yielded 5 different MCID estimates (range, 2-16). The 3-month mean change estimate of MCID was 10.4 points.
  
  
  CONCLUSIONS
  Our study demonstrates an MCID estimate of 10.4 points as the threshold for the Constant score in patients with rotator cuff tear.
  
  
  METHODS
  Basic science study, validation of outcomes instruments/classification systems.
authors.affiliation: Department of Orthopaedics and Traumatology, Turku University Hospital, Turku, Finland. Electronic address: jupeku@utu.fi.
authors.forename: Juha
authors.initials: J
authors.lastname: Kukkonen
authors.forename: Tommi
authors.initials: T
authors.lastname: Kauko
authors.forename: Tero
authors.initials: T
authors.lastname: Vahlberg
authors.forename: Antti
authors.initials: A
authors.lastname: Joukainen
authors.forename: Ville
authors.initials: V
authors.lastname: Aärimaa
mesh_terms: D000203:Activities of Daily Living; D018771:Arthralgia / Q000601:surgery; D001182:Arthroscopy; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D053580:Muscle Strength; D017060:Patient Satisfaction; D016059:Range of Motion, Articular; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D012785:Shoulder Joint / Q000601:surgery*; D013708:Tendon Injuries / Q000175:diagnosis* / Q000601:surgery; D016896:Treatment Outcome
keywords: Basic Science Study; Constant score; Validation of Outcomes Instruments/Classification Systems; minimal clinically important difference; rotator cuff tear