title: Psychometrican analysis and dimensional structure of the Brazilian version of melasma quality of life scale (MELASQoL-BP).
abstract: BACKGROUND
  Although asymptomatic, melasma inflicts significant impact on quality of life. MELASQoL is the main instrument used to assess quality of life associated with melasma, it has been validated in several languages, but its latent dimensional structure and psychometric properties haven´t been fully explored.
  
  
  OBJECTIVE
  To evaluate psychometric characteristics, information and dimensional structure of the Brazilian version of MELASQoL.
  
  
  METHODS
  Survey with patients with facial melasma through socio-demographic questionnaire, DLQI-BRA, MASI and MELASQoL-BP, exploratory and confirmatory factor analysis, internal consistency of MELASQoL and latent dimensions (Cronbach's alpha). The informativeness of the model and items were investigated by the Rasch model (ordinal data).
  
  
  RESULTS
  We evaluated 154 patients, 134 (87%) were female, mean age (± SD) of 39 (± 8) years, the onset of melasma at 27 (± 8) years, median (p25-p75) of MASI scores , DLQI and MELASQoL 8 (5-15) 2 (1-6) and 30 (17-44). The correlation (rho) of MELASQoL with DLQI and MASI were: 0.70 and 0.36. Exploratory factor analysis identified two latent dimensions: Q1-Q3 and Q4-Q10, which had significantly more adjusted factor structure than the one-dimensional model: Χ2 / gl = 2.03, CFI = 0.95, AGFI = 0.94, RMSEA = 0.08. Cronbach's coefficient for the one-dimensional model and the factors were: 0.95, 0.92 and 0.93. Rasch analysis demonstrated that the use of seven alternatives per item resulted in no increase in the model informativeness.
  
  
  CONCLUSIONS
  MELASQoL-BP showed good psychometric performance and a latent structure of two dimensions. We also identified an oversizing of item alternatives to characterize the aggregate information to each dimension.
authors: Universidade Estadual Paulista "Júlio de Mesquita Filho" (Unesp) - Botucatu (SP), Brazil.
authors: Camila Fernandes Pollo
authors: CF
authors: Maranzatto
authors: Universidade Estadual Paulista "Júlio de Mesquita Filho" (Unesp) - Botucatu (SP), Brazil.
authors: Hélio Amante
authors: HA
authors: Miot
authors: Universidade Estadual Paulista "Júlio de Mesquita Filho" (Unesp) - Botucatu (SP), Brazil.
authors: Luciane Donida Bartoli
authors: LD
authors: Miot
authors: Universidade Estadual Paulista "Júlio de Mesquita Filho" (Unesp) - Botucatu (SP), Brazil.
authors: Silmara
authors: S
authors: Meneguin
mesh_terms: D000328:Adult; D001938:Brazil; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008548:Melanosis / Q000523:psychology*; D008875:Middle Aged; D011594:Psychometrics; D011788:Quality of Life; D012016:Reference Values; D015203:Reproducibility of Results; D012959:Socioeconomic Factors; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires / Q000592:standards*; D013997:Time Factors