Long‐Term Physical Activity and Subsequent Risk for Rheumatoid Arthritis Among Women: A Prospective Cohort Study

Abstract

Objective To evaluate the effects of long‐term physical activity on subsequent risk of rheumatoid arthritis (RA) in a prospective cohort study. Methods This study investigated physical activity and RA risk among women from the Nurses' Health Study II (1989–2015). Physical activity exposures and covariates were prospectively obtained using biennial questionnaires. Two rheumatologists independently reviewed the medical records of women who self‐reported a new diagnosis of RA on biennial questionnaires and who screened positive for RA based on a supplemental survey. All incident RA cases met the 1987 American College of Rheumatology (ACR) or 2010 ACR/European League Against Rheumatism (EULAR) classification criteria for RA. The primary analysis investigated the long‐term cumulative average number of hours spent in recreational physical activity 2–8 years prior to the RA diagnosis, a time span chosen to reduce the potential for reverse causation bias, since early RA affects physical activity prior to diagnosis. Estimated Cox regression hazard ratios (HRs) with 95% confidence intervals (95% CIs) were used to assess the risk of RA serologic phenotypes (all, seropositive, or seronegative) in relation to physical activity categories. The analyses were adjusted for body mass index (BMI) at age 18 years and time‐varying potential confounders, and the mediating effect of updated BMI on the interaction between physical activity and RA risk was quantified. Results Among the 113,366 women analyzed, 506 incident RA cases (67.0% with seropositive RA) were identified during 2,428,573 person‐years of follow‐up. After adjustment for confounders, including smoking, dietary quality, and BMI at age 18 years, increasing cumulative average total hours of recreational physical activity was associated with a reduced risk of RA, as follows: HR 1.00 for <1 hour/week (reference), HR 1.00 (95% CI 0.78–1.29) for 1 to <2 hours/week, HR 0.92 (95% CI 0.72–1.17) for 2 to <4 hours/week, HR 0.84 (95% CI 0.63–1.12) for 4 to <7 hours/week, and HR 0.67 (95% CI 0.47–0.98) for ≥7 hours/week (P for trend = 0.02). The proportion of the effect between physical activity and RA mediated by updated BMI was 14.0% (P = 0.002) for all RA and 20.0% (P = 0.001) for seropositive RA. Conclusion Higher levels of physical activity were associated with reduced RA risk. These results add to the literature implicating metabolic factors in the pathogenesis of RA.

Adiposity and the risk of rheumatoid arthritis: a systematic review and meta-analysis of cohort studies

“…Because excess weight to a large degree is driven by diet and lifestyle factors 56 , it is possible that certain lifestyle-related risk factors (e.g. consumption of sugar-sweetened soft drinks and low physical activity) may contribute to the development of rheumatoid arthritis partly through an effect on adiposity 52 , 57 – 59 , and further studies are needed to clarify if this is the case.…”

“…Established or suspected risk factors for rheumatoid arthritis include age 7 , genetic predisposition (human leukocyte antigen (HLA)-DR4) 8 , smoking 9 , 10 , diet 10 – 12 , physical activity 13 , and obesity 14 – 24 . In addition, the global prevalence of rheumatoid arthritis has been reported to be approximately two times higher in women than in men 25 .…”

The importance of differences; On environment and its interactions with genes and immunity in the causation of rheumatoid arthritis

“…Only very few studies have been performed investigating effects of exercise on risk for RA development, and the largest one so far from our own groups failed to demonstrate any protective effects on disease incidence, but showed that individuals involved with regular exercise programmes before onset of RA had a significantly milder disease at onset as compared with individuals with a sedentary lifestyle [137]. In a recent study from the Nurses' Health Study, higher levels of physical activity were, however, associated with reduced RA risk [138].…”

The outcomes of bariatric surgery on rheumatoid arthritis disease activity: a prospective cohort study

“…Even so, the disease activity measurements were performed by different trained evaluators who were unaware of the specific therapeutic regimen to make the study more objective. Second, previous studies demonstrated that metabolic factors, including dietary intake and physical activity, were associated with the occurrence and disease activity [34][35][36] . However, as the setup of the parameters was mainly focused on the change in RA disease activity before and after treatment, data on these metabolic factors were not collected in this study.…”