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Validation and reliability of the Cardiff Visual Ability Questionnaire for Children using Rasch analysis in a Turkish population
  1. Zuhal Özen Tunay1,
  2. Deniz Çalişkan2,
  3. Derya Öztuna3,
  4. Aysun İdil4
  1. 1Eye Clinic, Zekai Tahir Burak Women's and Children's Health Education and Research Hospital, Ankara, Turkey
  2. 2Public Health Department, Ankara University, Ankara, Turkey
  3. 3Biostatistics Department, Ankara University, Ankara, Turkey
  4. 4Public Health Department, Low Vision Rehabilitation Center, Ankara University, Ankara, Turkey
  1. Correspondence to Dr Zuhal Özen Tunay, Göz Hastalıkları Polikliniği, Zekai Tahir Burak Kadın Sağlığı Eğitim ve Araştırma Hastanesi, Talatpaşa Bulvarı, Altındağ, Ankara 06230, Turkey; zuhaltunay{at}gmail.com

Abstract

Aim To develop a Turkish version of the 25-item Cardiff Visual Ability Questionnaire for Children (CVAQC) and to evaluate the validity and reliability of the questionnaire.

Methods The study involved two main phases. The first phase involved a cross-cultural adaptation of the CVAQC from English into Turkish. The second phase involved the completion of the Turkish version of the CVAQC by 150 partially sighted children (6–18 years old) and validity and reliability checks. Extent and construct validity were investigated using Rasch analysis and reliability by internal consistency and person separation index (PSI).

Results An adequate conceptual equivalence was achieved following the linguistic adaptation process. The dataset for validation comprised 150 participants, 88 (58.7%) of whom were male. Evidence of disordered thresholds was found for one item (item 17). This item was recorded by collapsing two categories and ordered thresholds were evident. All items of the CVAQC were found to fit the Rasch model (χ² (df)=59.90 (2), p=0.159). The internal construct validity was good (mean item fit (SD) −0.054 (1.132), person fit (SD) −0.629 (2.079)) indicating a single underlying construct. The reliability was good with Cronbach's α of 0.91 and PSI of 0.94. Differential item functioning (DIF) was tested for age, sex, diagnosis, degree of visual impairment, and comorbidity. Evidence of DIF was found on age for one item (item 10, reading the board at school).

Conclusions The Turkish version of the CVAQC is a valid, reliable, and unidimensional questionnaire for partially sighted children aged 6–18 years.

Trial registration number Ankara University Ethics Committees registry number 06-177-12.

  • Clinical Trial
  • Vision
  • Rehabilitation
  • Child health (paediatrics)
  • Low vision aid

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