title: Item reduction and psychometric validation of the Oily Skin Self Assessment Scale (OSSAS) and the Oily Skin Impact Scale (OSIS).
abstract: BACKGROUND
  Developed using focus groups, the Oily Skin Self Assessment Scale (OSSAS) and Oily Skin Impact Scale (OSIS) are patient-reported outcome measures of oily facial skin.
  
  
  OBJECTIVE
  The aim of this study was to finalize the item-scale structure of the instruments and perform psychometric validation in adults with self-reported oily facial skin.
  
  
  METHODS
  The OSSAS and OSIS were administered to 202 adult subjects with oily facial skin in the United States. A subgroup of 152 subjects returned, 4 to 10 days later, for test–retest reliability evaluation.
  
  
  RESULTS
  Of the 202 participants, 72.8% were female; 64.4% had self-reported nonsevere acne. Item reduction resulted in a 14-item OSSAS with Sensation (five items), Tactile (four items) and Visual (four items) domains, a single blotting item, and an overall oiliness item. The OSIS was reduced to two three-item domains assessing Annoyance and Self-Image. Confirmatory factor analysis supported the construct validity of the final item-scale structures. The OSSAS and OSIS scales had acceptable item convergent validity (item-scale correlations >0.40) and floor and ceiling effects (<20%). Cronbach's alpha coefficients ranged from 0.83 to 0.89 for the OSSAS and 0.82 to 0.87 for the OSIS, demonstrating excellent internal consistency. The a priori test–retest reliability criterion (intraclass correlation [ICC] ≥0.7) was met for one of the three OSSAS domains and one of the two OSIS domains. OSSAS and OSIS domains distinguished among groups that differed in patient-reported facial oily skin severity (P < 0.0001), and bother associated with oily skin (P < 0.0001).
  
  
  CONCLUSIONS
  The OSSAS and OSIS versions tested in this study have been found to have strong psychometric properties in this patient sample (adults with self-reported oily facial skin), as assessments of self-reported oily facial skin severity and its emotional impact, respectively.
authors.affiliation: Mapi Values, Bollington, UK. rob.arbuckle@mapivalues.com
authors.forename: Robert
authors.initials: R
authors.lastname: Arbuckle
authors.forename: Marci
authors.initials: M
authors.lastname: Clark
authors.forename: Jane
authors.initials: J
authors.lastname: Harness
authors.forename: Nicola
authors.initials: N
authors.lastname: Bonner
authors.forename: Jane
authors.initials: J
authors.lastname: Scott
authors.forename: Zoe
authors.initials: Z
authors.lastname: Draelos
authors.forename: Ronald
authors.initials: R
authors.lastname: Rizer
authors.forename: Yating
authors.initials: Y
authors.lastname: Yeh
authors.forename: Kati
authors.initials: K
authors.lastname: Copley-Merriman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001828:Body Image; D017281:Cost of Illness; D003430:Cross-Sectional Studies; D005145:Face; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000379:methods; D011788:Quality of Life / Q000523:psychology; D015203:Reproducibility of Results; D012629:Sebum; D012871:Skin Diseases / Q000523:psychology*; D011795:Surveys and Questionnaires / Q000592:standards; D055815:Young Adult