Women make up approximately 70% of rheumatoid arthritis incident cases across some major global markets.

Rheumatoid arthritis (RA) is an autoimmune disease characterised by systemic chronic inflammation of the joints, bone and cartilage erosion, and joint deformity. The body’s immune system attacks the synovial membrane (lining of the joints), leading to an inflammatory response.

The inflammation causes damage to the joint capsule and cartilage over time that cannot be reversed. RA is most commonly seen in patients aged between 40 and 60 but can begin at any age.

Arthritis in women: epidemiological analysis

GlobalData’s epidemiological analysis of RA found that the majority of the diagnosed incident cases in the eight major markets (8MM: the US, France, Germany, Italy, Spain, the UK, Japan and Australia) are women. It is not entirely clear why this skew towards women occurs.

Figure 1 presents the diagnosed incident cases of rheumatoid arthritis in the 8MM by sex, in those ages 18 years and older. In the 8MM as a whole, women make up approximately 255,000 cases while men make up only 118,000 cases, corresponding to a 68% to 32% split between the sexes. This trend of a higher proportion of cases in women is consistent throughout each of the markets.

8MM, sex-specific diagnosed incident cases of rheumatoid arthritis, ages greater than or equal to 18 years, 2017

Source: GlobalData
5EU = France, Germany, Italy, Spain and the UK. 7MM = 5EU, the US and Japan.

Understanding the skew towards women

Although it is not entirely clear why RA occurs more frequently in women, it is known that women tend to be more susceptible to autoimmune disorders than men. Some theories suggest that this skew towards women is due to sex hormones, genetic differences in immunity and genetic susceptibility.

Researchers have suggested that estrogen, progesterone and androgens influence the development of RA. Some researchers believe that women are at increased risk of developing RA because their immune systems tend to be more sophisticated than men’s.

Arthritis in women: inflammatory responses

Women naturally have stronger inflammatory responses than men when their immune systems are triggered and inflammation plays a key role in many autoimmune diseases, especially RA.

While this often results in superior immunity among women, it may also increase a woman’s risk of developing RA if something goes wrong. Current studies are looking into whether biological and lifestyle factor differences between men and women can explain the large difference in incident cases between the sexes