Higher Step Count Lowers Risk of Developing RA by 45%

Dylan McGagh

Credit: Medical Independent

A higher daily step count was linked to a lower risk of developing rheumatoid arthritis (RA), according to a prospective cohort study presented at the 2024 European Congress of Rheumatology (EULAR).¹ The benefits of incremental increases (1000 steps per day) were particularly notable among specific subgroups of patients including females, older age groups, and patients with a higher body mass index (BMI).

“Existing evidence on the association between physical activity and RA remains conflicted due to a reliance on self-reported physical activity questionnaires, which are crude and prone to recall bias,” wrote a team of experts led by clinical research fellow within the Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences at Oxford University. “Wearable devices, such as accelerometers can continuously and more objectively measure physical activity level.”

To analyze the dose-response link between daily step count—measured by a wrist-worn accelerometer—and incident RA, investigators used data from the UK Biobank, in which subjects wore the device for 7 days. Participants with prevalent inflammatory arthritis, including RA, psoriatic arthritis (PsA), or ankylosing spondylitis, were excluded from the study.

Daily steps were calculated using a hybrid self-supervised machine learning step detection algorithm. Patients’ physical activity was defined as the median daily step count over the 7-day period, as a continuous measurement, per quarters of steps (< 6818, 6819—9055, 9056—11659, and > 11659 steps), and per a 1000-step increase.

The link between step count and developing RA was determined using Cox proportional hazards models that adjusted for sociodemographic and lifestyle determinants. The incident RA cases were identified using record linkage with inpatient data from hospitals.

Investigators used subgroup analyses to study the association per 1000 step increase and incident RA, which was stratified by BMI (< 25, 24—29.9, and > 30 kg/m²), sex, and age (40—49, 50—59, 60—69, and 70—79 years). Sensitivity analyses that removed any RA diagnosis within 2 and 4 years of the trial were performed.

A total of 91,069 patients with a median age of 62.3 (SD 7.8) years and a median follow-up time of 7.9 years were included in the study. Among participants, there were 629 incident RA cases, equaling 87.4 cases per 100,000 person years.

A higher median daily step count was linked to a lower risk of incident RA, which was inverse log-linear. Patients in the highest quarter (> 11659 daily steps) had a 45% lower risk of RA compared with patients in the lowest quarter (< 6818 daily steps) (hazard ratio [HR] .55, [95% confidence interval (CI) .44 — .68]). A lower risk of developing RA was also observed across the second (6818—9055 steps) (HR .77 [.65 — .95]) and third (9056—11659 steps) (HR .72 [.60 – .86]) quarters compared with the lowest quarter.

A 5% lower risk of developing RA was observed per each 1000-step increase per day (HR .95 [CI .93 — .97]). The sensitivity analyses did not significantly impact these results. In the subgroup analyses, a 1000 step increase was linked to a lower risk among subjects in the overweight and obese BMI categories, female participants, and those aged 50 — 79.
“Further studies are needed to explore the association between physical activity and incident RA in at-risk individuals,” investigators concluded.

References

1. ^{McGagh, D, Acquah A, Portas L, Zisou C, et al. Association Between Accelerometer-Measured Daily Step Count and Incident Rheumatoid Arthritis: A Prospective Cohort Study in the UK Biobank. Presented at: EULAR. Vienna, Austria. June 12 – 15, 2024.}