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North American natives’ rheumatoid arthritis risk tied to pregnancy traits
Reproductive characteristics of North American native women had a significant effect on their risk for developing rheumatoid arthritis, according to study results.
Canadian researchers reviewed reproductive history questionnaires from 168 North American native (NAN) women with rheumatoid arthritis (RA) and 400 NAN women without RA, including relatives of the RA cohort and unrelated NAN participants.
Christine A. Peschken
NAN patients from several tribal groups have some of the highest rates of RA in the world, the researchers noted, including disease onset at a young age.
“We hope to gain a better understanding of the factors, genetic and environmental, leading to the development of RA, in order to improve outcomes,” researcher Christine A. Peschken, MD, MSc, FRCPC, assistant professor in the departments of medicine and community health services at University of Manitoba in Winnipeg, told Healio.com.
RA patients (mean age at disease onset, 37 years; mean disease duration, 12 years) and controls shared similarities in age, education, epitope frequency, number of pregnancies, age at first pregnancy, smoking and breastfeeding history. Using multivariate analysis, the risk for developing RA was lower for women who gave birth at least six times compared with women who had one to two births (OR=0.43; 95% CI, 0.21-0.87) and for women who gave birth for the first time after age 20 compared with women who delivered children for the first time at or before age 17 (OR=0.33; 95% CI, 0.16-0.66). The first postpartum year indicated the highest risk for developing RA compared with ensuing years (OR=3.8; 95% CI, 1.45-9.93).
“This population is very unique; clinicians not familiar with [it] may be surprised at the concentration of multiple known risk factors, such as the shared epitope,” Peschken said. “Perhaps surprising is the demonstration of apparently competing risks of the hormonal changes of pregnancy and the hormonal changes of the postpartum period; one protective, the other increasing risk. The caveat is that the population is unique, and the results may not be generalizable to others.”