title: Psychometric properties of the stagnation scale in medication overuse headache patients.
abstract: BACKGROUND
  Medication-overuse headache (MOH) is often comorbid with emotional disturbances, contributing to poorer outcomes. The aims of the present study were to assess the psychometric properties of the Stagnation Scale in a sample of MOH patients, and to compare two factor models: a three-factor model reported in previous studies and a proposed bi-factor model.
  
  
  METHODS
  Consecutive adult outpatients (N = 310) admitted to the Regional Referral Headache Centre of the Sant'Andrea Hospital in Rome (Italy) were administered the Stagnation Scale and two questionnaires measuring depression and perceived disability.
  
  
  RESULTS
  The original three-factor model demonstrated an adequate fit to the data (χ(2)(101) = 238.70; p < 0.001; Root Mean Square Error of Approximation [RMSEA] = 0.07; 90% CI of RMSEA = 0.06 / 0.08; Comparative Fit Index [CFI] = 0.98; Weighted Root Mean Square Residual [WRMR] = 0.75). However, the bi-factor model had a comparable or even better fit, with a RMSEA of 0.05 (90% CI: 0.04 / 0.07), providing strong evidence for an absolute fit to the data (χ(2)(88) = 161.43; p < 0.001; RMSEA = 0.05; 90% CI of RMSEA = 0.04 / 0.07; CFI = 0.99; WRMR = 0.56). The stagnation general factor and all the group factors correlated significantly and positively with convergent measures.
  
  
  CONCLUSIONS
  There is support for the use of the Stagnation Scale in MOH patients, with the goal of better understanding the role of psychological factors in the evolution and course of the disorder.
authors.affiliation: Department of Neurosciences, Mental Health and Sensory Organs, Suicide Prevention Center, Sant'Andrea Hospital, Sapienza University of Rome, Rome, Italy, innamorati.marco@libero.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Innamorati
authors.forename: Maurizio
authors.initials: M
authors.lastname: Pompili
authors.forename: Denise
authors.initials: D
authors.lastname: Erbuto
authors.forename: Federica
authors.initials: F
authors.lastname: Ricci
authors.forename: Monica
authors.initials: M
authors.lastname: Migliorati
authors.forename: Dorian A
authors.initials: DA
authors.lastname: Lamis
authors.forename: Mario
authors.initials: M
authors.lastname: Amore
authors.forename: Paolo
authors.initials: P
authors.lastname: Girardi
authors.forename: Paolo
authors.initials: P
authors.lastname: Martelletti
mesh_terms: D000328:Adult; D003863:Depression / Q000175:diagnosis; D004185:Disability Evaluation; D005260:Female; D051271:Headache Disorders, Secondary / Q000139:chemically induced / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011594:Psychometrics / Q000295:instrumentation*; D012384:Rome; D011795:Surveys and Questionnaires / Q000592:standards*