Comparison of the CAT-QoL and PedsQL^TM instruments in measuring quality of life in amblyopia treatment: preliminary results

ABSTRACT

Background/Aims: The Child Amblyopia Treatment Questionnaire (CAT-QoL) is a patient-reported outcome measure (PROM), designed to assess the impact of amblyopia treatment. The aim of this study was to compare the psychometric properties of two PROMs; the CAT-QoL instrument and Pediatric Quality of Life Inventory (PedsQL^TM), a generic pediatric PROM. This work was part of a wider project to develop a condition-specific PROM for children with amblyopia.

Methods: Three hundred and forty-two participants were recruited in a UK multi-center study. Quality of life data was collected using the CAT-QoL and the PedsQL^TM instruments. The psychometric performance of the CAT-QoL and PedsQL^TM were examined in terms of acceptability, reliability, and validity.

Results: Both instruments demonstrated good reliability (CAT-QoL Cronbach’s α = 0.793; PedsQL^TM α = 0.872). The convergent validity of the CAT-QoL and PedsQL^TM instruments was tested by comparing the instruments to each other. There was a moderate correlation between the PedsQL^TM and the CAT-QoL scores, and this relationship was statistically significant (r_s = −0.517, p < .000). No statistical significance was found between the level of amblyopia severity and the mean PedsQL^TM score (p = .420).

Conclusion: It was possible to assess the impact of amblyopia treatment using the CAT-QoL and PedsQL^TM instruments. The preliminary findings from this are not conclusive, and it is not possible to advocate the use of one questionnaire over another based upon psychometric performance demonstrated here. This may be due to the sample population, as there were limited numbers of participants with severe amblyopia. Both the CAT-QoL and PedsQL^TM instruments were noted to have some issues with ceiling effects at an individual item level. The CAT-QoL and PedsQL^TM were reliable (as determined by Cronbach’s alpha). The PedsQL^TM instrument was not able to discriminate between amblyopia severity groups (discriminant validity). Further research is required to formally assess the psychometric properties of the CAT-QoL questionnaire.

KEYWORDS:

• Amblyopia
• Quality of life
• Questionnaire
• Treatment

Acknowledgments

Data for this study was collected at the following sites: Bradford Teaching Hospitals NHS Foundation Trust; Doncaster and Bassetlaw NHS Foundation Trust; Harrogate and District NHS Foundation Trust; Maidstone and Tunbridge Wells NHS Trust; Medway NHS Foundation Trust; Sandwell and West Birmingham Hospitals NHS Trust; Sheffield Children’s NHS Foundation Trust; Sheffield Teaching Hospitals NHS Foundation Trust; The Mid Yorkshire Hospitals NHS Trust. The author gratefully acknowledges the support from orthoptists and clinicians at each of the collaborating sites.

This work is produced by the author under the terms of Personal Development Award research training fellowship issued by the NIHR. The views expressed in this publication are those of the author(s) and not necessarily those of the NHS, The National Institute for Health Research or the Department of Health.

Declaration of Interest

The authors report no conflict of interest.

Additional information

Funding

This work was supported by the National Institute for Health Research [PAS2/RDA/02/012].