title: The Core Outcome Measures Index (COMI) is a responsive instrument for assessing the outcome of treatment for adult spinal deformity.
abstract: The Core Outcome Measures Index for the back (COMI-back) is a very brief instrument for assessing the main outcomes of importance to patients with back problems (pain, function, symptom-specific well-being, quality of life, disability). However, it might be expected to be less responsive than a disease-specific instrument when evaluating specific pathologies. In patients with adult spinal deformity, we compared the performance of COMI-back with the widely accepted SRS-22 questionnaire.
  
  
  
  At baseline and 12 months after non-operative (N = 121) and surgical (N = 83) treatment, patients (175 F, 29 M) completed the following: COMI-back, SRS-22, Oswestry Disability Index (ODI) and SF-36 PCS. At 12 months' follow-up, patients also indicated on a 15-point Global Rating of Change Scale (GRCS) how their back problem had changed relative to 1 year ago. Construct validity for the COMI-back was assessed by the correlation between its scores and those of the comparator instruments; responsiveness was assessed with receiver operating characteristics (ROC) analysis of COMI-back change scores versus the criterion 'treatment success' (dichotomized GRCS).
  
  
  
  Baseline values for the COMI-back showed significant (p < 0.0001) correlations with SRS-22 (r = -0.85), ODI (r = 0.83), and SF-36 PCS (r = -0.82) scores; significantly worse scores for all measures were recorded in the surgical group. The correlation between the change scores (baseline to 12 months) for COMI and SRS-22 was 0.74, and between each of these change scores and the external criterion of treatment success were: COMI-back, r = 0.58; SRS-22, r = -0.58 (each p < 0.0001). The ROC areas under the curve for the COMI-back and SRS-22 change scores were 0.79 and 0.82, respectively.
  
  
  
  Both baseline and change scores for the COMI-back correlated strongly with those of the SRS-22, and differed significantly in surgical and non-operative patients, suggesting good construct validity. With the "change in the back problem" serving as external criterion, COMI-back showed similar external responsiveness to SRS-22. The COMI-back was well able to detect important change. Coupled with its brevity, which minimizes patient burden, these favourable psychometric properties suggest the COMI-back is a suitable instrument for use in registries and can serve as a valid instrument in clinical studies emerging from such data pools.
authors.affiliation: Spine Center Division, Department of Research and Development, Schulthess Klinik, Lengghalde 2, 8008, Zurich, Switzerland. anne.mannion@kws.ch.
authors.forename: A F
authors.initials: AF
authors.lastname: Mannion
authors.affiliation: Spine Research Unit, Vall d'Hebron Institute of Research, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Vila-Casademunt
authors.affiliation: Spine Research Unit, Vall d'Hebron Institute of Research, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Domingo-Sàbat
authors.affiliation: Spine Center Division, Department of Research and Development, Schulthess Klinik, Lengghalde 2, 8008, Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Wunderlin
authors.affiliation: Spine Surgery Unit, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Pellisé
authors.affiliation: Spine Surgery Unit, Hospital Vall d'Hebron, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Bago
authors.affiliation: Spine Surgery Unit, Ankara Spine Center, Ankara, Turkey.
authors.forename: E
authors.initials: E
authors.lastname: Acaroglu
authors.affiliation: Spine Surgery Unit, Acibadem Maslak Hospital, Istanbul, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: Alanay
authors.affiliation: Spine Surgery Unit, Hospital Universitario La Paz, Madrid, Spain.
authors.forename: F S
authors.initials: FS
authors.lastname: Pérez-Grueso
authors.affiliation: Spine Surgery Unit, Pellegrin Hospital, Bordeaux University Hospital, Bordeaux, France.
authors.forename: I
authors.initials: I
authors.lastname: Obeid
authors.affiliation: Spine Center Division, Department of Research and Development, Schulthess Klinik, Lengghalde 2, 8008, Zurich, Switzerland.
authors.forename: F S
authors.initials: FS
authors.lastname: Kleinstück
mesh_terms: D000328:Adult; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D011788:Quality of Life; D012372:ROC Curve; D013121:Spinal Curvatures / Q000453:epidemiology / Q000503:physiopathology / Q000601:surgery; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
keywords: Adult deformity; Core outcome measures; Non-operative treatment; SRS-22; Surgery