Long-Term Predictors of Physical Activity in Patients With RA

Regular physical activity can help improve symptoms of rheumatoid arthritis (RA) and prevent other diseases common in patients with RA, including cardiovascular disease; however, it can be difficult to know how physically active a patient is likely to be long term. A new study to be published in an upcoming issue of Arthritis Care & Research has shed additional light on this issue, identifying distinct trajectories of physical activity over 2 years and baseline predictors for each trajectory in a well-defined population with RA.¹

“We believe our study is the first to use longitudinal data to describe levels of physical activity over a long period of time in a large sample of patients with RA,” said Ingrid Demmelmaier, PhD, PT, Division of Physiotherapy, Karolinska Institute, Stockholm, Sweden, in an email interview with Rheumatology Advisor. “Although other studies have used various measures to examine physical activity in patients with RA, longitudinal trajectory analysis enabled us to identify predictors of patterns of physical activity over time, and we hope our findings will help clinicians better tailor their physical activity recommendations to their patients so that they can maintain higher levels of physical activity over time.”

Demmelmaier and colleagues’ study included 2752 persons aged 18 to 75 years who were independent in their activities of daily living and being treated for RA in Sweden. Using data collected from Swedish registers and questionnaires administered at baseline and at 14 and 26 months, the investigators identified 3 physical activity trajectories: stable high (n=272), where patients averaged 25 hours of physical activity per week; decreasing (n=564), where patients went from 22 hours to 8 hours of physical activity per week; and stable low (n=1916), where patients averaged 3 hours of physical activity per week.

“It is important to note that even those in the stable low category in our study exceeded the minimum recommendation of 150 minutes of exercise per week set by the American College of Sports Medicine and the American Heart Association,” said Demmelmaier. “International studies have shown significant differences in physical activity levels among RA patient populations, but because our study population appears to fall somewhere in the middle of extreme activity and inactivity, we believe our findings can be broadly applied and serve as a good base for clinical decision-making with regard to health-enhancing physical activities.”

When examining predictors for each trajectory, Demmelmaier and colleagues found that patients were more likely to be in the stable high trajectory than in the other trajectories if they were men and had established physical activity routines at baseline. Patients were also more likely to remain in the stable high trajectory and not move into the decreasing trajectory if they were younger and needed less social support for exercise. Finally, those in the stable high trajectory had fewer activity limitations and higher exercise self-efficacy than those in the stable low trajectory.

“We were really surprised by two findings: (1) that less social support for exercise was a predictor of being in the stable high group; and (2) that activity limitation was the only disease-related variable that predicted trajectory,” noted Demmelmaier. “We surmise the first finding may indicate that patients with an established exercise routine have formed a habit that does not require social support to be maintained, whereas the second finding highlights the need for clinicians to pay special attention to activity limitations in their patients with RA.”

Summary and Clinical Applicability

Demmelmaier and colleagues’ study indicates that female sex, older age, activity limitations, and the lack of an established physical activity routine at baseline can predict an inability to maintain high levels of physical activity over time. Keeping this information in mind, healthcare providers can better identify patients at risk of being more sedentary and tailor their interventions and physical activity recommendations accordingly.

Reference

1. Demmelmaier I, Dufour AB, Nordgren B, Opava CH. Trajectories of physical activity over two years in persons with rheumatoid arthritis. Arthritis Care Res (Hoboken). 2016 Jan 19. doi: 10.1002/acr.22799.