An Investigation of the Association between Metabolic Syndrome and Osteoporosis Based on Chinese Health Examination Data

Objective Because of the limited number of studies and small sample sizes, whether metabolic syndrome (MS) leads to the occurrence and progression of osteoporosis and the possible underlying mechanisms require further investigation. This study aimed to investigate the association between MS and osteoporosis, along with its influencing factors. Methods This observational cross-sectional study included 139,470 individuals aged >= 18 years who underwent health examinations from September 2014 to March 2022. Based on bone mineral density (BMD) screening results, the participants were categorized into a suspected osteoporosis or nonosteoporosis group (control). Participants were further divided into those who met 0 MS criteria, 1 MS criterion, 2 MS criteria, and >= 3 MS criteria (MS group). Participants who had undergone health examinations at least twice formed the follow-up cohort; a self-matched analysis was performed on those with follow-up periods >= 5 years and unchanged MS grouping. Results Several examination indicators in the suspected osteoporosis group showed statistically significant differences compared with the control group. The proportion of suspected osteoporosis in the MS group was significantly increased compared with that in the 0 MS criteria group (odds ratio [OR]: 1.215, Z = 29.11, P < 0.001, 95% confidence interval: 1.199-1.231). After adjusting for age, sex, smoking, and alcohol consumption, the 2 MS criteria group and MS group still had OR values > 1 (P < 0.001). In the follow-up cohort, the proportion of suspected osteoporosis increased gradually with an increase in the number of MS criteria met at baseline and during each follow-up visit (P < 0.05), with the highest proportion observed in the MS group. However, the proportion of suspected osteoporosis did not increase significantly over time in the different MS groups (P > 0.05). In the follow-up cohort, the proportion of individuals transitioning from normal BMD to suspected osteoporosis was higher in the MS group after >= 5 years of follow-up compared with the group meeting 0 MS criteria (0.08% versus 1.15%, chi(2) = 10.76, P = 0.001). There was no significant difference in BMD values for the 0 MS criteria group after 5 years (P > 0.05), whereas the other three groups experienced a significant decrease in BMD values after 5 years (P < 0.05). Conclusion MS is an independent risk factor for osteoporosis, and the effect of risk factors related to MS on osteoporosis may exceed that of aging alone. The specific mechanisms warrant further investigation.