An analysis of data from two large prospective cohorts indicate that a healthier lifestyle is associated with a lower risk of developing rheumatoid arthritis (RA). Jill Hahn, ScD, MS, a postdoctoral research fellow at the Harvard T.H. Chan School of Public Health, Boston, and colleagues conclude from this finding that a substantial proportion of RA may be preventable by a healthy lifestyle. They published their findings online Jan. 18 in Arthritis Care & Research.1
Dr. Hahn
Study Details
The team used a healthy lifestyle index with five modifiable, healthy lifestyle practices:
- Not smoking cigarettes;
- Maintaining normal weight (i.e., not being overweight or obese);
- Getting regular physical activity;
- Drinking alcohol only in moderation; and
- Following a healthy diet, low in saturated fats and carbohydrates.
Whereas past studies have demonstrated that not following each of these healthy lifestyle behaviors was individually associated with an increased risk of developing RA, the current study examined the factors in a continuing scale known as the Healthy Lifestyle Index Score (HLIS).2 Previous research has shown that adherence to such lifestyle guidelines contributes to health and protects against cancer and cardiovascular diseases.3–5
The Results
Hahn et al. analyzed cohorts that had detailed lifestyle data and lengthy follow-up. The 107,092 women in the Nurses’ Health Study (NHS, 1986–2016) and Nurses’ Health Study 2 (1991–2017) had a mean age of 43.7 years and a mean follow-up of 24 years per participant. The investigators identified 1,219 women with RA (776 seropositive and 443 seronegative). The condition had developed over 4,467,751 person-years. They found that women with the healthiest HLIS (i.e., 5) tended to be younger (mean = 41.1 years old) and live in U.S. census tracts with higher median household incomes (i.e., $51,887 median annual household income). Healthier women who were postmenopausal also tended to use hormones more than women with the least healthy HLIS score (i.e., 0). The least healthy women had a mean age of 46.7 years and a median annual household income of $41,959.
The team found that a higher (i.e., healthier) HLIS was associated with a lower overall, seropositive and seronegative RA risk (hazard ratio [HR] 0.86, 95% confidence interval [CI] 0.82–0.90; HR 0.85, 95% CI 0.80–0.91; HR 0.87, 95% 0.80–0.94, respectively). This association remained true even after adjusting for potential confounders, such as age, median family income parity, breastfeeding and hormone use.
The investigators then performed sensitivity analyses by lagging the physical activity exposure variable by four years behind the RA outcome assessment window. They did this to test the possibility that preclinical RA was causing less physical activity or an increase in body mass index (BMI). The findings did not change, and the researchers concluded from this finding that their analysis was not identifying reverse causation.
The researchers found that women with five healthy lifestyle factors had the lowest risk of developing RA and that the population-attributable risk (i.e, the incidence of RA in the population that would be eliminated if exposure were eliminated) for adhering to four or more of the five lifestyle factors was 34%, with the population-attributable risk for each individual factor ranging from 1% for physical activity to 17.3% for healthy BMI.
The investigators concluded from this that a substantial proportion of RA may be preventable by following a healthy lifestyle, and they emphasize in their paper the importance of this message for not only individuals at risk for RA by virtue of family history, but also the general population. That message includes the implication that even if a patient has reduced their risk of developing RA in in one category, such as not smoking, a patient has several other opportunities to further lower that risk.
“Healthy lifestyle behaviors are good for the prevention of many different diseases, and now RA is one of them,” says senior author Karen H. Costenbader, MD, MPH, a rheumatologist at Brigham and Women’s Hospital, Boston. “RA and chronic autoimmune diseases are traditionally thought of as mainly genetic diseases, and there is not much you can do about that. As it turns out, RA, like many chronic diseases, is related to environmental exposures and health behaviors.”
She describes this as a “paradigm shift in thinking about RA as a preventable disease.”
Implications for RA Outcomes
While acknowledging that the study does not specifically address outcomes, Dr. Costenbader notes that because “healthy lifestyle behaviors are strongly related to the risk of RA, it makes sense they [may also be] associated with outcomes from RA.”
Lara C. Pullen, PhD, is a medical writer based in the Chicago area.
References
- Hahn J, Malpeis S, Choi MY, et al. Association of healthy lifestyle behaviors and the risk of developing rheumatoid arthritis among women. Arthritis Care Res (Hoboken). 2022 Jan 18. Online ahead of print.
- Zaccardelli A, Friedlander HM, Ford JA, et al. Potential of lifestyle changes for reducing the risk of developing rheumatoid arthritis: is an ounce of prevention worth a pound of cure? Clin Ther. 2019 Jul;41(7):1323–1345.
- Stampfer MJ, Hu FB, Manson JE, et al. Primary prevention of coronary heart disease in women through diet and lifestyle. N Engl J Med. 2000 Jul 6;343(1):16–22.
- Chiuve SE, Rexrode KM, Spiegelman D, et al. Primary prevention of stroke by healthy lifestyle. Circulation. 2008 Aug 26;118(9):947–954. Epub 2008 Aug 12.
- Li Y, Schoufour J, Wang DD, et al. Healthy lifestyle and life expectancy free of cancer, cardiovascular disease, and type 2 diabetes: Prospective cohort study. BMJ. 2020 Jan 8;368:l6669.
