title: The Italian Catquest-9SF cataract questionnaire: translation, validation and application.
abstract: BACKGROUND
  To validate the Catquest-9SF questionnaire in Italian, assess the change in visual disability with cataract surgery and determine the correlation between pre-operative Catquest-9SF scores and Lens Opacities Classification System (LOCS) III cataract grading.
  
  
  METHODS
  Prospective, questionnaire validation study. The Catquest-9SF questionnaire was forward and back translated and completed by 209 Italian patients before and three months following cataract surgery. Rasch analysis was used to assess its psychometric properties.
  
  
  RESULTS
  The Italian Catquest-9SF demonstrated ordered response categories, unidimensionality (item fit statistics range: 0.73-1.34), adequate person separation (2.04), and no differential item functioning. Mistargeting was evident with a mean difference in item difficulty and person ability of 2.04 logits but improved with inclusion of pre-operative data only. There was a statistically significant (Friedman tests, p < 0.001) median improvement in visual disability of 1.92, 3.57, 1.44 and 2.94 logits in patients undergoing first eye surgery with and without ocular comorbidity, and second eye surgery with and without ocular comorbidity respectively. There was no statistically significant difference in the improvements among the four groups (Kruskal-Wallis H test, X (2) (3) = 5.445, p = 0.142). There was no correlation between Catquest-9SF scores and nuclear opalescence (r s = 0.049, p = 0.478), nuclear colour (r s = 0.008, p = 0.909), cortical (r s = 0.066, p = 0.341), and posterior subcapsular components (r s = 0.048, p = 0.494).
  
  
  CONCLUSIONS
  The Italian Catquest-9SF demonstrated good psychometric properties and is suitable for use in Italian speaking patients. There were similar improvements in visual disability in patients undergoing first or second eye surgery, with or without ocular comorbidity. There was no correlation between pre-operative Catquest-9SF scores and LOCS III cataract grading.
authors.affiliation: University Eye Clinic of Trieste, Ospedale Maggiore, Trieste, Italy ; Department of Ophthalmology, Singleton Hospital, ABM University Health Board, Swansea, SA2 8QA UK.
authors.forename: Eirini
authors.initials: E
authors.lastname: Skiadaresi
authors.affiliation: University Eye Clinic of Trieste, Ospedale Maggiore, Trieste, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Ravalico
authors.affiliation: University Eye Clinic of Trieste, Ospedale Maggiore, Trieste, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Polizzi
authors.affiliation: Department of Clinical Sciences, Ophthalmology, Faculty of Medicine, Lund University, Lund, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Lundström
authors.affiliation: Cornea & Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: González-Andrades
authors.affiliation: ABM University Health Board, Swansea, UK ; Flinders University, Bedford Park, Adelaide, South Australia Australia ; Wenzhou Medical University, Wenzhou, Zhejiang China.
authors.forename: Colm
authors.initials: C
authors.lastname: McAlinden
keywords: Cataract; Cataract surgery; Catquest-9SF; Patient-reported outcomes; Questionnaires; Rasch analysis