The validation of the Hong Kong Chinese Version of the Lawton Instrumental Activities of Daily Living scale for institutionalized elderly persons

The Lawton Instrumental Activities of Daily Living (IADL) scale is the assessment tool most commonly used by occupational therapists in Hong Kong. However, there has been no cross-cultural validation study of the Lawton IADL-Chinese Version (IADL-CV) scale as applied to Hong Kong's older adults. This was the first study of content validity, construct validity, and reliability of the Lawton IADL-CV. A total of 155 institutionalized older adults were recruited from three different hostels and one care-and-attention home by using a convenience sampling method. Expert panel review and pilot testing on the subjects established the linguistic and content validity of the Hong Kong Chinese version. The content of the scale, the scoring criteria, translation, and level of rating scale were examined. It was shown that all nine IADL items apart from "handyman work" were culturally relevant (more than 78% agreement). Nine items altogether had good representation in assessing the IADL ability of Hong Kong older adults (73% agreement). The scoring criteria were refined with reference to the local culture. Both panel review and the related psychometric properties supported the change of the level of rating scale from a three-point to a four-point scale. The inter-rater and test-retest reliability estimated by intraclass correlation coefficient (ICC) gave a value of 0.99 and 0.90, respectively. The Cronbach's alpha estimating the internal consistency was 0.86. In the study of the construct validity, the factor analysis and known-groups methods were used. The construct validity was examined by factor analysis of the Lawton IADL scores of 111 hostel subjects. The result showed that one factor was extracted from the nine items of the Lawton IADL-CV scale. The known-groups method was performed using the Lawton IADL-CV to separate 146 institutionalized subjects into their corresponding living institutions: hostel or care-and-attention home. An overall prediction ability of 78% was achieved so as to correctly discriminate between residents in the hostel and care-and-attention home. In conclusion, the Lawton IADL-CV scale is a valid and reliable instrument to assess the older adults' IADL ability to live independently in the community.