Risk Factors

Environmental, genetic and hormonal factors having an association with the immune system’s attack on body joints have been speculated as potential risk factors for RA.³⁸ Since specific causative agents have yet to be identified, suppressed immune systems, and infections serve as contributing factors in some individuals. Inflammation affecting organ systems contributes to systemic manifestations.⁵⁸ Evidence is mounting around infectious agents, such as bacteria or viruses triggering RA conditions in susceptible individuals.⁵⁸ The Human Herpes Virus 6 (HHV-6) and Epstein-Barr virus (EBV) have been confirmed in epidemiological studies to have potential associations.⁵¹ RA is familial with a 2-3% prevalence rate for first-degree relatives, and a genetic disease component with identical twins is approximately at 15-20%.⁶² Genetic components demonstrating positive RA factors have been associated with disease severity and may interact with a well-defined environmental factor such as cigarette smoking.^58,63 In fact, smokers are four times more likely to exhibit RA conditions than non-smokers.⁶³

Individuals with autoimmune disorders suffer from the inability to recognize foreign invaders from their body’s own. Clusters of genetic markers, HLA-DR4/DR1 occur in 90% of those with RA, allowing susceptibility through genetic factors and infectious episodes triggering autoimmune responses.^63,64

Research has suggested complex interactions exist between RA and estrogen and female sex hormones as influencing risks. The onset of RA is rare during pregnancy, can often return post-delivery, and is more common among nulliparous women. Oral contraceptive use seems to reduce the risk of developing rheumatoid arthritis (RA) by 13%, according to a Swedish population-based case-control study. Nulliparity, frequency of oral contraception use, and breast-feeding may all influence the epidemiology of RA. Breastfeeding has been associated with a decreased risk of RA, and a long duration of breastfeeding appears to have the strongest association. However, some studies have found an increased RA risk.⁶⁵