Urban-Rural Differences in Bone Mineral Density and its Association with Reproductive and Menstrual Factors Among Older Women

Genetic Prediction of Osteoporosis by Anti-Müllerian Hormone Levels and Reproductive Factors in Women: A Mendelian Randomization Study

Previous observational studies have suggested that anti-Müllerian hormone (AMH) and reproductive factors are linked to reduced bone mineral density (BMD) and an increased risk of osteoporosis (OP) in women. However, related studies are limited, and these traditional observational studies may be subject to residual confounders and reverse causation, while also lacking a more comprehensive observation of various reproductive factors. Univariate and multivariate two-sample Mendelian randomization analyses were conducted to determine the causal associations of AMH levels and six reproductive factors with BMD and OP, using the random-effects inverse-variance weighted method. Heterogeneity was assessed using Cochran's Q-statistic, and sensitivity analyses were performed to identify causal correlations. Age at menarche (AAM) was negatively associated with total body BMD (TB-BMD) in females aged 45-60 and over 60 years, as well as with heel bone mineral density (eBMD). Conversely, age at natural menopause (ANM) was positively associated with TB-BMD in the same age ranges and with eBMD. ANM was only causally associated with self-reported OP and showed no significant correlation with definitively diagnosed OP. Neither AMH level nor other reproductive factors were significantly associated with a genetic predisposition to BMD at any age and OP. Later AAM and earlier ANM are significantly genetically causally associated with decreased BMD but not with OP. AMH levels, length of menstrual cycle, age at first birth, age at last birth, and number of live births, in terms of genetic backgrounds, are not causally related to BMD or OP.

Green space, genetic susceptibility, and risk of osteoporosis:a cohort study from the UK Biobank

OBJECTIVE

This study aimed to investigate the effect of residential exposure to green space on the incident osteoporosis and further explore the modification effect of genetic susceptibility.

METHODS

Participants from the UK Biobank were followed from 2006 to 2010 (baseline) to December 31st, 2022. Using land use coverage, we evaluated exposure to residential surrounding green space, natural environment, and domestic gardens. We used the Cox regression to examine the association between the residential environment and incident osteoporosis. The interactive effects between polygenic risk score (PRS) of osteoporosis and residential environments on incident osteoporosis were investigated.

RESULTS

This study included 292,662 participants. Over a median follow-up period of 13.65 years, we documented 9177 incidents of osteoporosis. Per interquartile (IQR) increase in greenness and natural environment at a 300 m buffer was associated with a 4% lower risk of incident osteoporosis [HR = 0.96 (95% CI: 0.93, 0.99)] and [HR = 0.96 (95% CI: 0.93, 0.98)], respectively. We did not identify any interactive effects between genetic risk and residential environment on incident osteoporosis.

CONCLUSIONS

This study found that public greenness and natural environments could reduce the risk of incident osteoporosis regardless of genetic predisposition. Developing sustainable and publicly accessible natural environments might benefit populations' bone health.

Development and validation of a predictive model of abnormal uterine bleeding associated with ovulatory dysfunction: a case-control study

BACKGROUND

Abnormal uterine bleeding associated with ovulatory dysfunction (AUB-O) is a typical gynecological disease that can affect women of various ages. Being able to identify women at risk of AUB-O could allow physicians to take timely action. This study aimed to identify the influencing factors of AUB-O in Chinese women, and then develop and validate a predictive model.

METHODS

In this multicenter case-control study, 391 women with AUB-O and 838 controls who came from nine hospitals in Zhejiang province were recruited between April 2019 and January 2022. All the participants completed a structured questionnaire including general characteristics, lifestyle and habits, menstrual and reproductive history, and previous diseases. The predictive model was developed on a group of 822 women and validated on a group of 407 women. Logistic regression was adopted to investigate the influencing factors and develop the model, and validation was then performed.

RESULTS

The independent predictive factors of AUB-O were age (OR 1.073, 95% CI 1.046-1.102, P < 0.001), body mass index (OR 1.081, 95% CI 1.016-1.151, P = 0.015), systolic blood pressure (OR 1.016, 95% CI 1.002-1.029, P = 0.023), residence (OR 2.451, 95% CI 1.727-3.478, P < 0.001), plant-based diet (OR 2.306, 95% CI 1.415-3.759, P < 0.001), fruits eating (OR 1.887, 95% CI 1.282-2.776, P = 0.001), daily sleep duration (OR 0.819; 95% CI 0.708-0.946, P = 0.007), multiparous (parity = 1, OR 0.424, 95% CI 0.239-0.752, P = 0.003; parity > 1, OR 0.450, 95% CI 0.247-0.822, P = 0.009), and history of ovarian cyst (OR 1.880, 95% CI 1.305-2.710, P < 0.001). The predictive ability (area under the curve) in the development group was 0.77 (95% CI 0.74-0.81), while in the validation group it was 0.73 (95% CI 0.67-0.79). The calibration curve was in high coincidence with the standard curve in the development group, and similar to the validation group. A tool for AUB-O risk calculation was created.

CONCLUSIONS

Nine influencing factors and a predictive model were proposed in this study, which could identify women who are at high risk of developing AUB-O. This finding highlights the importance of early screening and the lifelong management of ovulatory disorders for women.

Association between age at menarche and bone mineral density in postmenopausal women

BACKGROUND

Age at menarche (AAM) directly affects female estrogen levels, which play a vital role in bone metabolism. The exact relationship between bone mineral density (BMD) and AAM remains controversial. Thus, this study aimed to determine the association between AAM and lumbar spine (LS) BMD in postmenopausal women.

METHODS

Our data were based on the National Health and Nutrition Examination Survey (NHANES) 2011-2018. AAM was divided into three categories including ≤ 12, 13-15, and ≥ 16 years, and the ≤ 12 years old category was used as the reference group. To examine the association between AAM and LS BMD, we used three weighted linear regression models, Model 1 (without adjustment), Model 2 (with adjustment for age, race, and body mass index [BMI]), and Model 3 (with adjustment for all covariates).

RESULTS

This study included 1195 postmenopausal women aged 40-59 years. In the unadjusted model, a menarche age of ≥ 16 years compared with a menarche age of ≤ 12 years was associated with lower LS BMD (β = - 0.083, 95% CI - 0.117, - 0.048, P < 0.001). After adjusting for potential confounding factors, there was still a negative correlation in model 2 (β = - 0.078, 95% CI - 0.113, - 0.042, P < 0.001) and model 3 (β = - 0.065, 95% CI - 0.096, - 0.033, P < 0.001). Moreover, this significant relationship persisted after excluding participants who used female hormones (β = - 0.053, 95% CI - 0.089, - 0.016, P = 0.006).

CONCLUSION

Our study found that postmenopausal women with a menarche age of ≥ 16 years had significantly lower LS BMD than that had by those with a menarche age of ≤ 12 years. As a result of this study, postmenopausal women with a late menarche age may have a higher risk of lumbar osteoporotic fractures and need better bone health care.

Vitamin D Status and Bone Health in Postmenopausal Women Working in Greenhouses

Objectives

Greenhouse workers synthesize less vitamin D because ultraviolet light is blocked by the vinyl that covers the greenhouses. This study aimed to investigate the vitamin D status and bone health of postmenopausal women working in greenhouses.

Methods

This observational study enrolled women living in urban (n = 70, group 1) and rural areas (n = 91, group 2) and those working in greenhouses (n = 112, group 3). Serum levels of total and bioavailable 25-hydroxy-vitamin D [25(OH)D] and vitamin D binding protein were measured. T-scores of the lumbar spine and femur neck were measured by dual-energy X-ray absorptionetry.

Results

Heights were shorter in group 2 and group 3 than in group 1. Bioavailable 25(OH)D levels were higher and T-scores of the spine and femur were lower in both group 2 and 3 than in group 1. T-scores of the femur in group 3 were lower than those in group 2. The linear regression analysis showed that levels of bioavailable 25(OH)D significantly correlated with the spine T-scores but not with the femur T-scores. The prevalence of spinal osteoporosis was higher in both groups 2 and 3 compared to group 1. Group 3 demonstrated greater femur osteoporosis compared to groups 1 and 2.

Conclusions

Vitamin D plays an important role in spinal bone health. Moreover, working conditions are likely to play an important role in femur bone health. Therefore, appropriate working conditions and nutrition are paramount to improve bone health in postmenopausal women working in greenhouses.

Influence of Residence Area and Basic Livelihood Conditions on the Prevalence and Diagnosis Experience of Osteoporosis in Postmenopausal Women Aged over 50 Years: Evaluation Using Korea National Health and Nutrition Examination Survey Data

Patients with osteoporosis are asymptomatic and are at risk for fractures. Therefore, early detection and interventions are important. We found that a population with a low socioeconomic status living in rural areas was reported to have a high osteoporosis prevalence but a relatively low diagnosis rate. Research on the disparity of osteoporosis prevalence and treatment from the socioeconomic perspective was conducted. This study aimed to investigate the influence of residence area and basic livelihood conditions on osteoporosis prevalence and diagnosis in postmenopausal women aged over 50 years. The cross-sectional data of 1477 postmenopausal women aged over 50 years obtained from the Korea National Health and Nutrition Examination Survey V-2 were analyzed. Univariate analyses were performed to calculate the prevalence and diagnosis rate according to risk factor categories. A multivariate logistic regression analysis was performed to identify the influence of residence area and basic livelihood conditions after controlling for other factors. The osteoporosis prevalence in basic livelihood beneficiaries (53.7%) and rural area residents (41.9%) was higher than that in non-beneficiaries (33.1%) and urban area residents (31.8%). There was no significant difference in the diagnosis rates in relation to the basic livelihood conditions or residence areas. The adjusted odds ratio for the prevalence among the beneficiaries living in rural areas was 2.08 (95% confidence interval: 1.06-4.10). However, the odds ratio for diagnosis was not significantly different. Earlier screening examination policies for osteoporosis in postmenopausal women with a low socioeconomic status living in rural areas are needed.

MYLK and PTGS1 Genetic Variations Associated with Osteoporosis and Benign Breast Tumors in Korean Women

Osteoporosis, characterized by reduced bone mass and increased bone fragility, is a disease prevalent in women. Likewise, breast cancer is a multifactorial disease and considered the major cause of mortality in premenopausal and postmenopausal women worldwide. Our data demonstrated the association of the MYLK gene and PTGS1 gene variants with osteoporosis and benign breast tumor risk and the impact of ovariectomy on osteoporosis in Korean women. We performed a genome-wide association study (GWAS) of women with osteoporosis and benign breast tumors. There were 60 single nucleotide polymorphisms (SNPs) and 12 SNPs in the MYLK and PTGS1 genes, associated with benign breast tumors and osteoporosis. Our study showed that women with homozygous MYLK rs12163585 major alleles had an increased risk of osteoporosis following ovariectomy compared to those with minor alleles. Women carrying the minor PTGS1 rs1213265 allele and not treated via ovariectomy carried a higher risk of osteoporosis than those who underwent ovariectomy with a homozygous genotype at the major alleles. Our results suggest that both the MYLK and PTGS1 genes are genetic factors associated with the phenotypes, and these associations appear to be modulated by ovariectomy.