Bone mineral density decreases less than expected after menopause

Bone mineral density at the femoral neck bone in postmenopausal women decreased by an average of 10% during a 25-year follow-up, according to a new study from the University of Eastern Finland. Being the world’s hitherto longest follow-up of changes in bone mineral density in postmenopausal women, the study shows that bone loss after menopause is significantly lower than has previously been assumed on the basis of earlier studies. Women with the highest bone mineral density at baseline had the highest bone loss percentage when compared to baseline.

The Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study began in 1989 with a health survey that was sent to all women aged 47–56 living in the Kuopio region, eastern Finland. A total of 14,200 women received the survey, and it has been repeated at five-year intervals. In addition, a randomised sample of 3,000 women have participated in bone mineral density measurements every five years. The study is still ongoing, with 30-year measurements currently under way.

Published in Journal of Bone and Mineral Research, the present findings are from the 25-year follow-up. The study included all OSTPRE study participants who had participated in all of the bone mineral density measurements during the 25-year follow-up.

Abstract

The aim of this study was to monitor long-term changes in bone mineral density (BMD) after menopause and factors affecting BMD. The study population consisted of a random sample of 3222 women from the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study, of which 62.1% were postmenopausal at the beginning of the study. This group of women underwent dual-energy X-ray absorptiometry (DXA) measurements at the femoral neck every 5 years from baseline (in 1989) up to 25-year follow-up. They also responded to risk-factor questionnaires at 5-year intervals. During the 25-year follow-up, the baseline cohort decreased to 686 women. The women were divided into quartiles based on their baseline BMD. Self-reported hormone replacement therapy (HRT) and corticosteroid use were divided into ever users and never users. Morbidity was assessed as the total number of self-reported diseases and BMD-affecting diseases. The mean 25-year BMD change was found to be −10.1%, p < 0.001. Higher baseline BMD was associated with higher bone loss rate; the reduction in the highest quartile BMD was 11.1% and in the lowest quartile 7.4% (p = 0.0031). Lower baseline body mass index (BMI) and a greater increase in BMI were found to protect against postmenopausal bone loss (p < 0.001). The lowest bone loss quartile included 15.2% more HRT users than the highest bone loss quartile (p = 0.004). The number of diseases/bone-affecting diseases, use of vitamin D/calcium supplementation, use of corticosteroids, smoking or alcohol use had no statistical significance for annual bone loss rate. This study presents hitherto the longest (25-year) BMD follow-up in postmenopausal women. The linear femoral neck bone loss of 10% was less than previously assumed. A 5-year BMD change appeared to predict long-term bone loss in postmenopausal women.

Reference

Anna Moilanen, Juho Kopra, Heikki Kröger, Reijo Sund, Toni Rikkonen, Joonas Sirola. Characteristics of Long‐Term Femoral Neck Bone Loss in Postmenopausal Women: A 25‐Year Follow‐Up. Journal of Bone and Mineral Research, 2021; DOI: 10.1002/jbmr.4444