The effect of hormone therapy (HT) on the risk of developing rheumatoid arthritis (RA) after menopause has been uncertain, but now a study from Sweden suggests that HT may decrease the risk for one subset of the disease:RA positive for antibodies to citrullinated peptides (ACPA).
The study, by researchers at the Karolinska Institute, was presented at the recent annual meeting of the American College of Rheumatology (ACR) in San Diego.
The investigators studied 380 incident RA cases between 2006 and 2009 among postmenopausal women (ages 50-70) from the Swedish population-based case-control study called EIRA (Epidemiological Investigation of RA).
They matched women with RA by age and residence with 780 randomly selected controls. Both groups answered a questionnaire about HT use within the past year or previously.
Among the RA cases 239, or 63%, tested positive for ACPA antibodies.
Current HT users had only half the prevalence of ACPA-positive RA compared with never-users ()R range 0.3-0.8, confidence interval 95%. The research team found no association for ACPA-negative RA among current or past users.
“Compared with ACPA-negative, ACPA-positive RA is a more severe form of the disease,” principal investigator Orellana, who is a PhD candidate at Karolinska, pointed out in an interview. “So our research suggests hormones may actually protect women from a worse form of RA, which is good news.”
But why? The mechanism is not yet known.The researchers note that their data add “further evidence to the notion that RA consists of two different entities with partly different etiology.”