Background/Purpose: Physical function and performance are top priorities to individuals with systemic lupus erythematosus (SLE). Suboptimal physical function and performance are associated with disability, loss of independence, and mortality, but disparities in physical function and performance remain poorly understood. We leveraged data from two large population-based cohorts to compare self-reported physical function and measured physical performance across two U.S. populations of individuals with SLE.

Methods: Approaches to Positive, Patient-centered Experiences of Aging with Lupus (APPEAL) participants were recruited from the Georgians Organized Against Lupus (GOAL) cohort for a one-time study visit (10/2019–5/2022). California Lupus Epidemiology Study (CLUES) participants were from the third wave of ongoing data collection (1/2018–9/2019). Participants were included in this analysis if they had complete data for both the Short Physical Performance Battery (SPPB; score range: 0–12) and PROMIS Physical Function 10a/10b (CLUES/APPEAL; T-scores for both). Additional variables included age, sex, race/ethnicity, BMI, measures of SLE activity [Systemic Lupus Activity Questionnaire (SLAQ)] and damage [Brief Index of Lupus Damage (BILD)], disease duration, and depression (CLUES: Patient Health Questionnaire (PHQ)-8; APPEAL: PROMIS Depression Short Form 8b). Demographic and clinical characteristics were examined by cohort. The associations of cohort membership with physical function and physical performance were estimated using multivariable linear regression.

Results: Mean age was similar in APPEAL (N&#3f446) and CLUES (N&#3f173; 46 vs 45 years) and both cohorts were predominantly female (APPEAL 92% vs. CLUES 90%; Table 1). However, the APPEAL cohort was primarily Black (81%), whereas CLUES included a higher proportion of Asian (41%), White (28%), and Hispanic (23%) participants. Lupus disease activity and damage were higher among APPEAL participants (SLAQ: 9 vs. 14; BILD: 3 vs. 2). Self-reported physical function was lower among APPEAL compared to CLUES participants, with mean T scores of 41.5 and 47.9, respectively, as was measured physical performance (Figure 1), with 60% having an SPPB score < 10 (vs. 46% in CLUES). After adjustment for age and sex, physical function T-scores were 0.64 SD (6.4 points) lower among APPEAL compared to CLUES participants (Table 2). This association, however, was no longer statistically significant after adjustment for clinical factors. Further adjustment for race did not substantively change the association between cohort membership and physical function. Similar relationships were observed for SPPB scores (Table 2).

Conclusion: Despite similar age and sex distributions, participants in the APPEAL cohort had significantly lower physical function and performance compared to those in the CLUES cohort. Importantly, these differences were largely explained by clinical characteristics, particularly disease activity, and not by differences in race/ethnicity between the cohorts. Because SLE activity is potentially reversible, targeted interventions to reduce disease activity may help mitigate disparities in physical function and performance.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/physical-function-and-performance-in-sle-a-comparison-of-two-population-based-cohorts/