Correlation between bone mineral density and bone metabolic markers in postmenopausal women with osteoporotic fractures at different C-terminal telopeptide of type 1 collagen levels: a retrospective analysis study

Objective: This study aimed to analyze the correlation between bone mineral density (BMD) and bone resorption markers in postmenopausal women with osteoporosis fractures and identify risk factors for second fractures. Methods: This retrospective analysis of 1,239 older women with fractures with a median age of 70 years who attended Shanghai General Hospital from January 2007 to December 2016, included a first fracture group (1,008 cases) and a second fractures group (231 cases). The risk factors for fractures were analyzed by comparing these groups on clinical characteristics, BMD, and bone metabolism markers stratified by quartiles of serum C-terminal telopeptide of type 1 collagen (CTX). Binary logistic regression analysis was used to identify risk factors for second fractures. Results: In the whole sample, BMD was negatively correlated with age and serum osteocalcin and positively correlated with body mass index (BMI). In women with first fractures, those in the highest quartile of serum CTX had the lowest spine and hip BMD. Second fractures were significantly associated with BMI, lower spine and hip BMD, and higher serum osteocalcin but not CTX. Binary logistic regression analysis showed that high BMI (odds ratio [OR], 1.08 [95% CI, 1.03-1.14]; P = 0.001), low lumbar BMD (OR, 0.24 [95% CI, 0.07-0.82]; P = 0.023), low total hip BMD (OR, 0.05 [95% CI, 0.00-0.88]; P = 0.041), and lack of antiosteoporosis treatment (OR, 2.71 [95% CI, 2.71-4.08]; P < 0.001) were independent risk factors for second fractures. Conclusions: In older women with fractures, BMD was significantly lower in women with second fractures than in those with first fractures. Higher levels of serum CTX and osteocalcin, which indicates increased bone resorption, were negatively correlated with BMD. In women with a first fracture, serum CTX higher than 605 pg/mL was negatively correlated with BMD, whereas no correlation was found between different CTX and BMD in women with second fractures. High BMI and low BMD as well as not receiving antiosteoporosis treatment were independent risk factors for second fractures.