Association between the serum cotinine and trabecular bone score in the adult population: A cross-sectional study

INTRODUCTION Trabecular bone score (TBS) is gaining attention as a novel approach for evaluating bone quality, as it provides insights into skeletal microarchitecture. We aimed to investigate the possible relationship between serum cotinine and TBS in the US population. METHODS This cross-sectional study utilized data from the 2005-2008 National Health and Nutrition Examination Survey (NHANES). A total of 6961 adults aged >= 20 years with complete data on TBS and serum cotinine were included. Serum cotinine levels were measured using isotope-dilution high-performance liquid chromatography coupled with tandem mass spectrometry. TBS was derived from lumbar spine DXA images using the Med-Imap SA TBS Calculator. Weighted multivariable linear regression analyses were conducted, adjusting for age, sex, race, BMI, poverty income ratio (PIR), total spine bone mineral density (TSBMD), smoking status, C-reactive protein (CRP), total protein, blood urea nitrogen, serum creatinine, serum uric acid, serum calcium, alkaline phosphatase, and serum phosphorus. Subgroup analyses were stratified by sex, race, BMI, and PIR. RESULTS A total of 6961 individuals were included in the analysis, with a mean (+/- SE) age of 45.20 +/- 0.39 years, comprising 49.21% males and 50.79% females. The serum level of cotinine was negatively associated with TBS in the fully adjusted model. Specifically, for each unit increase in the log2-cotinine score, there was a corresponding 0.01 unit decrease in TBS ((3=-0.01; 95% CI:-0.02 --0.01, p=0.002). Participants in the highest tertile of serum cotinine had a significantly lower TBS compared to those in the lowest tertile ((3=-0.01; 95% CI:-0.02 --0.01, p=0.002). Subgroup analysis revealed a significant negative association between serum cotinine and TBS in females ((3=-0.021; 95% CI:-0.03 --0.01), but not in males. No significant associations were found when stratified by race, BMI, and PIR. CONCLUSIONS Serum cotinine was negatively associated with TBS in US adults. Further large-scale prospective studies are still needed to explore the associative relationship of cotinine in TBS.