The use of oral contraceptives before or at the time of symptom onset in women with inflammatory polyarthritis appears to confer long-term benefits in functional outcome.
In the largest-ever prospective study of the relationship between oral contraceptives and disease outcome, data from the Norfolk (U.K.) Arthritis Register showed that OC use prior to symptom onset was associated with a 35% reduction in median Health Assessment Questionnaire (HAQ) scores at 5 years of follow-up, compared with women who hadn't taken OCs beforehand.
Moreover, the benefit of taking OCs around the time of symptom onset was even greater. Women on OCs at symptom onset had a 21% lower median HAQ score at 5 years, after adjustment for age, parity, and other potential confounders, than women who weren't taking OCs at symptom onset but had previously done so.
OC use during follow-up was also associated with lower HAQ scores, but this finding reached significance only for the subset of women with moderate or severe functional disability at their previous assessment.
The study involved 523 users and 140 nonusers of OCs prior to onset of inflammatory polyarthritis, along with 73 OC users and 192 nonusers at symptom onset, and 95 users and 170 nonusers during follow-up, which lasted a median of 4.9 years. The median score on the HAQ, a validated measure of functional ability, was 1.0 on a 0-3 scale at symptom onset, indicative of moderate disability, Dr. Deborah P.M. Symmons and her coworkers reported in Arthritis & Rheumatism (2011;63:2183-91).
Although the Norfolk Arthritis Register is open to patients with inflammatory polyarthritis, it has previously been established that 75% of enrollees meet American College of Rheumatology diagnostic criteria for rheumatoid arthritis within 5 years of symptom onset.
The investigators offered two potential mechanisms to explain the observed relationship between OC use and disease outcome. One possibility is that the hormonal environment fostered by OCs results in an increase in heat-shock proteins, resulting in an immunotolerant state that reduces rheumatoid arthritis symptoms. Another potential mechanism is that the artificial luteal phase induced by combined estrogen/progesterone OCs tempers rheumatoid arthritis symptoms; this is consistent with an earlier report by other investigators that rheumatoid arthritis symptoms in 14 women were significantly reduced just after ovulation, wrote Dr. Symmons, a professor of rheumatology and musculoskeletal epidemiology at the University of Manchester (England), and her colleagues.
The Norfolk Arthritis Register is funded by Arthritis Research UK. Dr. Symmons and her coinvestigators reported having no financial conflicts.