Item generation and content validation of domains with item pool for the individual with knee osteoarthritis: a mixed-method study

Abstract

INTRODUCTION: There are several scales to evaluate subjective perceptions and individual components in individuals with knee osteoarthritis (IKOA). Till date, no scale is available to measure the combined balance, mobility, ADL and QoL in IKOA based on the International Classification of Functioning, Disability and Health (ICF). OBJECTIVE: The purpose of the study was to generate items and domains related to problems faced by IKOA and to validate the content by experts. METHODS: The domains and items were generated through extensive literature search (ELS) to extract items related to symptoms, balance, mobility, ADL and QoL in IKOA based on the International Classification of Functioning, Disability and Health (ICF) and through in-depth direct interview (IDDI) from 13 IKOA and three experts. The content validation of domains and items generated were validated by 10 experts through online Delphi survey. Minimum item-level content validation index (I-CVI) of 0.80 was considered to validate the identified items and the overall scale-level content validation index (S-CVI) of 0.90 was fixed to validate the generated items to use in scale development process. RESULTS: 117 items generated by IDDI and ELS were grouped under 18 domains initially. Content validation by Delphi method resulted in reduction with 56 item pool being grouped under the 14 domains with SCVI is 0.93. CONCLUSION: The comprehensive impairment, activity limitation and participation restriction item pool for IKOA under the proposed domains, have been developed and content validated. These items are recommended for their use in development of new comprehensive knee osteoarthritis index scale (CKOAI).