Postmenopausal women taking menopausal hormone therapy (MHT) were significantly less likely to develop symptomatic knee osteoarthritis (OA) compared with those who did not take MHT, a nationwide cross-sectional observational study shows. But both the authors and an outside expert say the results should be viewed with caveats in mind.
“Participants receiving MHT had a significantly lower prevalence of symptomatic knee OA compared with those who did not receive MHT. However, this cross-sectional study precludes conclusions about causal relationships, so further prospective studies and intervention trials should be undertaken to establish a causal association between knee OA and MHT,” the researchers write.
Jae Hyun Jung, MD, PhD, from Korea University College of Medicine, Inchon-ro, Seongbuk-gu, and the Division of Rheumatology, Department of Internal Medicine, Korea University Guro Hospital, Gurodong-ro, Guro-gu, both in Seoul, South Korea; and colleagues report their findings in an article published online December 21 in Menopause.
The researchers analyzed data from 4766 postmenopausal women who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) between 2009 and 2012. They defined MHT as receiving regular hormone medication for at least 1 year and defined knee OA according to symptoms and radiographic findings.
The 441 women in the MHT group were 30% less likely to have OA compared with the 4325 women in the non-MHT group (odds ratio, 0.70; 95% confidence interval, 0.50 – 0.99), after adjusting for MHT duration, age, obesity, age of menarche and menopause, hypertension, diabetes mellitus, alcohol intake, smoking status, and socioeconomic status.
“[T]he P value according to MHT showed statistical significance, but the 95% [confidence interval] was close to 1.00. This suggests that reproducibility problems may arise if other participants are included in this survey,” the researchers explain. “However, the results were meaningful because the KNHANES participants represent the entire Korean population with minimum selection bias.”
Leonard Reeves, MD, a practicing family physician in Rome, Georgia, urges clinicians to exercise caution when interpreting these study results. “The [American Academy of Family Physicians (AAFP)] and [US Preventive Services Task Force (USPSTF)] recommend against hormone replacement therapy in postmenopausal women, as the harms of estrogen therapy outweigh the benefits. According to the USPSTF, although the use of hormone therapy to prevent chronic conditions in postmenopausal women is associated with some benefits, there are also well-documented harms,” Reeves told Medscape Medical News.
“This study was conducted in Korea, so the results may not translate to the US. There are many factors that differ between the two countries and populations. Additionally, the authors acknowledge that since the confidence interval approaches 1, the addition of more patients may diminish the observed effect. Therefore, it is important to not overestimate the impact of the study and carefully weigh the benefits and harms of treatment,” Reeves explained.
All general characteristics differed significantly between the MHT and non-MHT groups except hypertension, smoking status, and household income level. Age, body mass index, and the prevalence of diabetes “were significantly higher in the non-MHT group than in the MHT group,” the authors write.
Education level was higher in the group that received MHT compared with the group that did not. The MHT group was younger at menarche and older at menopause compared with the non-MHT group.
“Past and current users of hormone therapy had a lower prevalence of knee joint osteoarthritis, suggesting that hormone therapy may be protective against knee osteoarthritis,” JoAnn Pinkerton, MD, North American Menopause Society executive director, said in a news release. “This study suggests that estrogen taken at menopause may inhibit cartilage damage and reduce knee deterioration seen on x-rays.”
The authors and Reeves have disclosed no relevant financial relationships.
Menopause. Published online ahead of print December 21, 2018. Abstract