Assessing Activity Limitations Caused by Rheumatoid Arthritis to Inform Appropriate Selection of Patient-Reported Outcomes Measures

OBJECTIVES: To comprehensively identify activity limitations (AL), including but not limited to impairments in physical function, experienced by people with rheumatoid arthritis (RA) and identify Patient-Reported Outcomes Measurement Information System (PROMIS) short form (SF) scales that can measure these limitations.

METHODS: A cross-sectional, web-based survey was conducted among adults with RA who were members of PatientSpot (PS) (formerly ArthritisPower), an online patient-powered research network (registry). PROMIS Upper Extremity (UE) SF7a, and Physical Function (PF) SF8b were used to assess AL caused by RA. An open-ended question asking what other AL respondents experienced was also included. The AL in the text response and PROMIS SF scale items were deductively coded using the International Classification of Functioning, Disability, and Health (ICF) based on an established linking rule.

RESULTS: Eighty-five out of 98 respondents answered the open-ended question. The AL domains reported by these respondents included “Mobility,” “Self-care,” “Domestic life,” “General tasks and demands,” “Interpersonal interactions and relationships,” “Major life areas: Work and employment,” and “Community, social and civic life: Recreation and leisure” under the category of activities and participation in ICF. UE SF7a and PF SF8b captured the first three of these domains, while the other domains could be captured by Fatigue SF7a and Ability to Participate in Social Roles and Activities (PSS) SF4a. Moreover, PF SF10a covered more AL than using both UE SF7a plus the PF SF8b.

CONCLUSIONS: People with RA reported several domains of AL that are not covered by the PROMIS UE SF7b and PF SF8b. PF SF10a may be a more effective and efficient scale than using both UE SF7a and PF SF8b to measure AL among RA patients. Fatigue SF7a and PSS SF4a also should be considered in future RA clinical trials and observational studies to examine important domains of AL caused by RA that may help guide treatment decisions.