Greater Self-Reported Disability Linked to Worse Disease Activity, Physical Function in Patients With Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) self-reporting greater disability, measured by the Health Assessment Questionnaire-Disability Index (HAQ-DI), had worse disease activity and pain, physical performance, and muscle strength at both baseline and over time, according to a study published in PLoS One.¹

“RA is a systemic chronic autoimmune disease that affects articular synovial tissue and can lead to joint damage and deformities,” investigators explained. “Often, RA patients also present with sarcopenia: decreased muscle strength and muscle mass with significant impact on physical performance. In addition to adverse changes to body composition, fat infiltration within the muscle is also observed in association with low physical function, low muscle strength and low physical activity.”

Two prospective cohorts comprised of patients with RA were evaluated to ascertain the association between disability and clinical features, muscle strength, and physical performance over time. HAQ-DI, a handgrip test, a chair stand test, Disease Activity Score in 28 Joints (DAS28), timed-up-and-go (TUG) test, and Short Physical Performance Battery (SPPB) were conducted at both baseline and follow-up. Clinical and demographic information, such as age, gender, treatment, disease duration, and presence of erosion was collected via medical records. Associations between individual constructs at baseline and over time were assessed using linear regression, Spearman correlation coefficients, T test for independent samples, and Mann-Whitney U test for independent samples.

In total, 205 adult patients (aged 18 to 70 years) with RA included, with 115 enrolled in the North American (University of Pennsylvania) cohort and 90 enrolled in the Brazilian (Universidade Federal do Rio Grande do Sul) cohort. The mean age was 56.2 years in combined cohorts, 53.0% were female in the North American group, and 86.7% were female in the Brazilian group.

At baseline, Brazilian men reported a better HAQ-DI when compared with North American men (1.8 [0.7–2.1] vs 0.6 [0.2–1.1], respectively; p < 0.001). However, Brazilian women had lower muscle strength when compared with North American women (14.7 ± 8.3 kg vs 19.8 ± 9.2 kg, respectively; p = 0.013). HAQ-DI was linked to the handgrip test, chair stand test, TUG, DAS28, and SPPB in both groups (p < 0.001).

A longitudinal analysis over time indicated that a worsening of HAQ-DI in patients was associated with a worsening of DAS28 and chair stand test. A worsening of handgrip was also linked to worsening HAQ-DI in both patient populations (p < 0.05). In the Brazilian patients, a worse TUG test was linked to worsening HAQ-DI and in North American patients, a worse SPPB was linked to worsening HAQ-DI (both p < 0.05).

Although the study was the first to prospectively evaluate a link between improvements in physical function and assessments of physical performance or muscle strengths, it also had some limitations. The lack of age- and sex-matched controls hindered results. Investigators note that by adding physical activity data over time, they may have been able to better understand the impact of exercise in this patient population. Further, a severely affected subgroup could not be studied due to the small number of patients reporting severe disability as measured by HAQ-DI.

“Changes in HAQ seem to be associated with changes in objectively assessed strength and physical function, suggesting HAQ captures the patient impact of sarcopenia-related disability,” investigators concluded.

Reference:

Santo RCDE, Baker JF, Dos Santos LP, et al. Changes in physical function over time in rheumatoid arthritis patients: A cohort study. PLoS One. 2023;18(1):e0280846. Published 2023 Jan 23. doi:10.1371/journal.pone.0280846