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Performance-based measure of hand, foot function sensitive to long-term changes in RA
Hand and foot function assessed with the signals of functional impairment instrument among patients with rheumatoid arthritis may complement self-reported and medical data, in the clinic and in research, according to data published in Arthritis Care & Research.
“The performance-based measures used vary considerably between countries, and in Sweden the instrument Signals of Functional Impairment (SOFI) has been included in some largescale longitudinal cohort studies,” Ann Bremander, PT, PhD, of Lund University, Sweden, and colleagues wrote. “This instrument rates performance tests according to range of movement in the hand, the upper extremity, and the lower extremity. ... Performance based measures are time consuming and expensive, and are often not included in larger prospective cohort studies and registry studies. However, their added value for understanding and prediction of disease outcome is important to study.”
To analyze physical function using the SOFI instrument over 8 years, the clinical variables associated with those changes, and to study change over time of the SOFI items, Bremander and colleagues evaluated a subset of patients with RA from the BARFOT (Better Anti-Rheumatic PharmacOTherapy) cohort. Patients with RA were recruited into the BARFOT study at diagnosis, between 1992 and 2006. Four of six BARFOT centers reported both SOFI summary and item scores. These data were included in the study. A total of 1,223 BARFOT participants were included in the researchers’ analysis.
Bremander and colleagues studied data from baseline and from years 1 to 8. Trained assessors used SOFI to evaluate physical function in participants, including measures of range of motion and exercises in the hand, the shoulder and arm, and the lower extremity. The SOFI scale ranges from a best of 0 to a worst of 44. The researchers used linear regression analysis to analyze the effects of baseline variables — including sociodemographic, disease activity, joint destruction and function — on change in SOFI scores.
According to the researchers, participants demonstrated a mean SOFI improvement of 2.7 (SD = 5.7; P < .001) in the first year. This improvement was associated with worse DAS28 and HAQ scores at baseline (r2 .11). Throughout the next 7 years, there was a mean deterioration in SOFI of 1.5 (SD = 4.9; P < .001). Finger flexion, pincer grip and toestanding were the most important items to measure, based on change scores, explaining 58% to 61% of the total SOFI score. These measures were also associated with radiographic changes at 8 years.
“Function assessed with SOFI improved during the first year in patients with early RA; it deteriorated slowly thereafter,” Bremander and colleagues wrote. “Finger flexion, pincer grip, and toe-standing showed the greatest changes over time, and were also associated with joint damage at eight years. We suggest that these three performance measures should be included in the clinical follow-up and in prospective research studies to complement patient-reported information.” – by Jason Laday
Disclosure: Bremander reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.