Who Gets Rheumatoid Arthritis & Why?
Approximately 1% of people worldwide have rheumatoid arthritis, with no specific geographic concentration. RA affects all races almost uniformly, with only Native American populations experiencing a higher prevalence rate (5-6%).
The majority of RA sufferers are 40-60 years of age, with prevalence of the disease increasing with age. More women get rheumatoid arthritis than men (3:1 or greater); more men tend to get rheumatoid arthritis at older ages.
Despite extensive research by the medical scientific community, the cause of RA is unknown. A number of factors are thought to play a role, including genetic and environmental:
- Multiple genes have been identified as possible culprits, but because there is insufficient correlation between the presence of these genes and actual occurrences of rheumatoid arthritis, other factors must also be responsible for triggering the disease
- Bacteria and viruses are thought to be involved, but the search for conclusive evidence of these so-called ‘infectious agents’ in initiating rheumatoid arthritis in any group (genetically pre-disposed or not) has been unsuccessful to date.
- Smoking is the only known modifiablerisk factor in the development of rheumatoid arthritis.
Studies have shown that people with siblings who suffer from RA will have a slightly higher chance of themselves developing RA (especially with identical twins), reinforcing the likelihood of a genetic link.
Because of the huge number of genes that must be considered and tested, it is very difficult to explain the ultimate genetic source, corresponding factors, and mechanisms of the disease.