Arthritis therapy may impact rates of unplanned pregnancy

Exposure to anti-tumor necrosis factor (anti-TNF) drugs for rheumatoid arthritis (RA) rather than methotrexate may be associated with increased rates of induced abortion, according to the results of a nested case-control study by Canadian researchers. The findings, say the investigators, point to a need for contraceptive counseling for women being treated for RA to lower the likelihood of unplanned pregnancy.

Published in Arthritis Care and Research, the analysis was based on information from Quebec’s physician billing and hospitalization databases from 1996 to 2008. Women aged 15 to 45 with RA were identified, with cases defined as those who had an induced abortion and 5,855 controls being women with RA who had not undergone the procedure. Each case was matched to a control for age, calendar time, and cohort entry. Exposure was defined as having filled one prescription for methotrexate 16 weeks or less before the index date.

The researchers identified 112 women with RA who had induced abortions. Nearly 11% of cases and 22% of controls were exposed to methotrexate. The rate of induced abortions was lower in those exposed to methotrexate (RR 0.74; 95% CI 0.25, 0.89) than in those who received an anti-TNF agent. In multivariate analysis, a trend was seen toward an increased rate of induced abortions in those who had taken the anti-TNF agents (RR 2.07; 95% CI 0.81, 5.27).

“These findings,” said lead author Evelyne Vinet, MD, “highlight the importance of research on reducing the number of unplanned pregnancies in women with RA taking MTX or TNF inhibitors. Further examination of counseling practices and contraceptive use is warranted to further reduce the need for abortions in women with RA.”