Incidence and Prevalence of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease associated with chronic inflammation of the joints. In 2008, the New York Times published a review on the incidence of rheumatoid arthritis among women. The report emphasized that after four decades of decline of arthritis in the US, the disease is currently on the rise, thus becoming an imminent health concern. From 1955-1994, the prevalence of arthritis among women was declining, 36 per 100,000 population compared to the current prevalence of 54 persons per 100,000 population (Parker-Pope, 2008). However, the disease prevalence in men remains about 29/100,000 (Parker-Pope, 2008). Among the US population, RA condition increased from 0.85% to 0.95%, (Parker-Pope, 2008), an increase of 11.8% in new cases. The risk factors for the RA condition is multifactorial, but some of the known risk factors are smoking, caffeine, diet, infection, sex hormone, reproductive factors, and BMI (≥30kg/m²) or obesity (Parker-Pope, 2008).

Crowson et al., (2013) conducted a controlled study among patients with arthritis from Minnesota County. The inclusion criteria for the study included individuals aged 18 years or older. Those who fulfilled the 1987 American College of Rheumatology classification criteria for RA between Jan 1st, 1980 to Dec21st 2007 (Crowson et al., 2013). The authors suggested that the recent rise in the prevalence and incidence of RA are associated with extrinsic factors because genetic factors do not change quickly in the population. Hence, the risk factor targeted in the study was obesity (Crowson et al., 2013). The evidence presented to support the theory was that, in recent years, obesity incidence and prevalence have been dramatically increased in the population (Crowson et al., 2013). The study included 813 patients in the experimental group (individuals with RA) and 813 individuals in the control group (individuals without RA) (Crowson et al., 2013).

Obesity rate between the experimental group and the control group was 40% vs. 36% respectively; P= 0.052 (Crowson et al., 2013). In 1985, the estimated incidence of RA among women in the absence of obesity was 45.4/100,000 populations, and in 2007, the incidence of RA was 49.8/100,000 (Crowson et al., 2013). In other words, the increase in RA incidence in the absence of obesity is 4.4/100,000 in time (Crowson et al., 2013). Also, the authors assessed the incidence of the condition among women with obesity. In 1985, the prevalence of the disease among obese women was 46.6/100,000 (Crowson et al., 2013). The age-adjusted RA incidence among obese women in 2007 was 55.8/100,000 (Crowson et al., 2013). Thus, the increase in RA incidence among obese women from 1985 to 2007 was 9.2/100,000. Therefore, among women, the risk attributed to obesity is 4.8/100,000 (9.2 minus 4.4), which is a 109% increase in the incidence of RA among women from 1985 to 2007.

No doubt, RA risk factors are multifactorial. Obesity, vitamin D deficiency, adipocytokines, autoimmune disease (via Vitamin D deficiency), and sex hormone variation (the increase of estrogen and androgen level in obese individuals) are intricately linked to RA; and also, are associated with the development of Psoriatic’ arthritis (Crowson et al., 2013). Furthermore, Crowson et al. (2013) suggested that if the continual increase in the prevalence of obesity or obesity epidemic are not controlled and managed; the incidence and prevalence of RA will continue to rise substantially.


Crowson,C., Matteson, E., Davis III, J., & Gabriel, S. (2013). Contribution of obesity to the rise in incidence of rheumatoid arthritis. Retrieved from doi/10.1002 /acr.21660/full

Parker-Pope, T. (2008). Rheumatoid arthritis rising in women. Retrieved from http://well.blogs.