Validity and Reliability of the Persian version of Lawton Instrumental Activities of Daily Living Scale among patients with Dementia

The Lawton IADL (instrumental activities of daily living) Scale is considered as one of the widely used tools to assess activities of daily livings in patients with dementia, but its validity and reliability has never been assessed in Persian-speaking populations. The purpose of this study was to investigate the validity and reliability of this widely used scale among patients with Dementia. International quality of life assessment (IQOLA) protocol was used for translating the Lawton Scale. After forward and backward translation, the 8 item questionnaire including use of telephone, shopping, meal preparation, housework, laundry, transportation, medication management and money management was evaluated for content validity by five experts in this field. Inter-rater and test-retest reliability assessment with one week interval were conducted by two occupational therapists. Results are reported based on data of sixty patients with Dementia referring to Iranian Alzheimer’s Association. Experts’ agreements regarding the construct validity was very high in 6 items and moderate in 2 items. There was no significant difference in agreement among experts in all 8 items (p>.05). The correlations of test-retest with relative and absolute coefficients were high (r = 0.993 and SEM = 0.238), (CI: 0/988-0/996). Also, the correlation coefficients between the raters (r = 0.961) were significant, indicating the high reliability of this test. The correlation of questions with total score of the test was average (0.606>r>0.427). These results confirm that the Persian version of the Lawton IADL Scale has excellent reliability and validity. The Lawton scale is an applicable tool to assess the functional capacity of patients with dementia and can be used by professionals and researchers.