Do patient-reported outcome measures cover personal factors important to people with rheumatoid arthritis? A mixed methods design using the International Classification of Functioning, Disability and Health as frame of reference.

Background: Personal factors (PFs) are internal factors that determine functioning and the individuals' experience of disability. Their coverage by patient-reported outcome measures (PROMs) has not been examined in rheumatoid arthritis (RA) so far. The aims of this study were to identify PFs important in the life stories of people with RA and to determine their coverage by PROMs used in RA.

Methods: The qualitative data of people with RA was explored to identify PFs. Additionally a systematic literature search was conducted to find PROMs used in RA. PROMs items were linked to the components, domains and categories of the International Classification of Functioning, Disability and Health (ICF) to determine the coverage of important PFs by PROMs.

Results: Twelve PFs were found to be important in the life stories of people with RA. The PFs coping and reflecting about one's life in an optimistic way were covered most frequently, each by 14 of the 42 explored PROMs, while job satisfaction was not covered at all. The London Coping with Rheumatoid Arthritis Questionnaire, General Self-Efficacy Scale, Arthritis Self-Efficacy Scale, Rheumatoid Arthritis Self-Efficacy Questionnaire and Revised Ways of Coping Inventory covered most PFs. Nineteen PROMs did not cover any of the PFs.

Conclusion: Several PFs were identified as important in the life stories of people with RA, but only 55% of the PROMS covered some of these PFs. When evaluating PFs important to people with RA, health professionals should be alert on which PROMs can be used to assess which PFs.