Objective We leveraged data from two population-based SLE cohorts Approaches to Positive, Patient-centered Experiences of Aging with Lupus (APPEAL) and California Lupus Epidemiology Study (CLUES) to provide estimates of, and identify factors associated with, perceived and objective physical function and their discordance. Methods Perceived physical function PROMIS Physical Function 12a/10a (APPEAL/CLUES; T-scores, mean = 50 and SD = 10) and objective physical function Short Physical Performance Battery (SPPB; score range: 0–12); higher scores=better function for both scores were examined by cohort and characteristics. We assessed factors associated with discordance between scores (2 quartiles different) using multinomial logistic regression. Results APPEAL (N=446; 81.4% Black) vs. CLUES (N=173; 41.0% Asian, 27.7%, White 23.1%) participants had lower perceived (T-scores, 41.5 vs. 47.9) and objective (SPPB scores, 9.0 vs. 9.4) physical function; there was no difference after adjustment for disease activity and cumulative disease damage. Factors associated with lower perceived and objective physical function across cohorts included oldest vs. youngest age (T-scores: 40.8 vs. 47.4; SPPB scores: 8.9 vs. 9.6), Black vs. White race (40.8 vs. 45.6; 8.9 vs. 9.7), and higher vs. lower disease activity (38.1 vs. 48.4; 8.7 vs. 9.6). Overall, 22.3% of participants had discordant scores; older age and higher disease activity were independently associated with lower risk of overestimating (objective<perceived score) physical function. Conclusion Our results show that perceived and objective physical function can vary considerably between SLE populations and by characteristics. Perceived physical function may not always reflect objective physical function in SLE populations.
Plantinga et al. (Thu,) studied this question.