Differences Observed Among Ethnic Groups for PROMIS Physical Function Short Form in RA

An X-Ray of rheumatoid arthritis
An X-Ray of rheumatoid arthritis
Overall, the PROMIS Physical Function Short Form has good measurement properties and is both practical and acceptable for implementation in routine clinical practice.

The Patient Reported Outcome Measurement Information System (PROMIS) Physical Function Short Form 10a (PF10a) is practical and acceptable for use in rheumatoid arthritis (RA) in clinical practice, but it has some limitations across racial and ethnic groups that should be investigated, according to results published in Arthritis Care & Research.

The PROMIS-PF10a is a 10-item questionnaire that assesses current self-reported physical function, with higher scores representing better physical function.

The study included data from electronic health records on all patients with RA seen in a university-based rheumatology clinic between 2013 and 2017. The researchers evaluated the PF10a’s use, floor/ceiling effects, and construct validity across categories of language preferences, insurance, and race or ethnicity. They evaluated the responsiveness of the PROMIS-PF10a to longitudinal changes in the Clinical Disease Activity Index (CDAI) across population subgroups using standardized response means and linear mixed-effects models.

The cross-sectional analysis of validity included 595 participants who had at least 1 set of complete data, including a pain score, PROMIS-PF10a score, CDAI score, serum C-reactive protein, and erythrocyte sedimentation rate. The longitudinal responsiveness analyses included 341 participants, all of whom had at least 2 complete data sets.

The results indicated that the PROMIS-PF10a had acceptable floor and ceiling effects. Overall, it was implemented successfully.

The researchers found that PF10a scores were strongly correlated (r≤-0.60) with participant global assessment of RA activity across all groups except Chinese speakers (r=-0.52) and patients insured by Medicaid (r=-0.53). They found that PROMIS-PF10a scores had strong correlations with pain in all groups except Chinese speakers (r=-0.52) and African Americans (r=-0.53).

The results indicated that correlations between PROMIS-PF10a and clinical outcomes were moderate (-0.3≥ r >-0.6) in most groups except among Chinese speakers and Hispanics; both of these groups showed weak correlations (r>-0.3).

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Using a linear mixed effects regression, the researchers found that both clinical improvements and deteriorations were associated with changes in PROMIS-PF10a scores over time (P <0.001), which suggests that PROMIS-PF10a is responsive to changes in clinical disease activity. However, the PROMIS-PF10a was less sensitive to clinical improvements among participants insured by Medicaid or who were Spanish speakers.

“Consistent with prior research, PF10a has strong measurement properties and is responsive to longitudinal changes in disease activity among whites, English speakers, and privately insured patients,” the researchers wrote. “However, our study highlights important differences across racial/ethnic groups and those with limited English proficiency.”

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Izadi Z, Katz PP, Schmajuk G, et al. Effects of language, insurance and race/ethnicity on measurement properties of the PROMIS Physical Function Short Form 10a in rheumatoid arthritis [published online August 12, 2018]. Arthritis Care Res (Hoboken). doi:10.1002/acr.23723