Objective: to investigate the correlation between cardiometabolic index (CMI) and lumbar spine bone mineral density (LSBMD) in U.S. adults.
Methods: the study selected eligible participants from the National Health and Nutrition Examination Survey (NHANES) database from 2011 to 2018. After adjusting for age, gender, race/ethnicity, body mass index (BMI), liver function markers, kidney function markers, blood routine indicators, metabolic markers, and chronic disease status, a logistic regression model combined with a restricted cubic spline model, smooth curve fitting, and threshold effect analysis was used to examine the association between CMI and LSBMD. Subgroup analysis was performed to verify the robustness of the results.
Result: among the 3,885 participants, for each unit increase in CMI, LSBMD decreased by 0.011 g/cm². Additionally, a turning point was identified at CMI = 0.797. When CMI was below 0.797, LSBMD decreased as CMI increased, showing a strong negative correlation (β = -0.077, 95 % CI: -0.097 to -0.058, p < 0.001). However, beyond this threshold, the relationship between CMI and LSBMD was no longer significant. Subgroup analysis revealed that the negative correlation between CMI and BMD was consistent across most subgroups (such as gender, BMI, hypertension, and high cholesterol), but instability was observed in subgroups such as individuals aged 51-59, Mexican Americans, non-Hispanic Blacks, and those with diabetes.
Conclusion: there exists a non-linear inverse correlation with CMI and LSBMD, showing that CMI could be a potential contributing factor for decreased bone mineral density, with a more pronounced effect within a specific range.