Differences between questionnaire- and interview-based measures of activities of daily living (ADL) ability and their association with observed ADL ability in women with rheumatoid arthritis, knee osteoarthritis, and fibromyalgia.

OBJECTIVES: Although self-report based on questionnaire is the common method to obtain information about activities of daily living (ADL) ability in rheumatic diseases, little is known about the relationship between measures of ADL ability based on questionnaire, interview, and observation. The present study examined whether measures of self-reported ADL ability based on questionnaire and interview yielded different results, determined whether the magnitude of the difference varied among women with rheumatoid arthritis (RA), knee osteoarthritis (OA), and fibromyalgia (FM), and investigated the relationships between self-reported and observed ADL ability.
METHOD: The 47 ADL tasks of the ADL taxonomy were used to evaluate self-reported ADL ability based on questionnaire (ADL-Q) and interview (ADL-I), and the Assessment of Motor and Process Skills (AMPS) was used to obtain measures of observed ADL ability.
RESULTS: Participants across diagnostic groups reported significantly more ADL ability based on the ADL-Q than on the ADL-I. Moderate correlations were found between the ADL-Q and ADL-I ability measures. Although low to moderate correlations were seen between measures based on the AMPS ADL motor scale and the ADL-Q and ADL-I, respectively, correlations between measures based on AMPS ADL process scale and ADL-Q and ADL-I were generally low. Overall, there was no difference in how the measures based on the two modes of self-report related to the observed ADL ability measures.
CONCLUSION: Measures of self-reported ADL ability based on either questionnaire or interview have limited relationship to each other or to observed performance of ADL tasks.