Bone Turnover Markers and Bone Mineral Density to Predict Osteoporotic Fractures in Older Women: A Retrospective Comparative Study.

Objective: To investigate the clinical significance of the detection of bone mineral density (BMD) and bone turnover markers (BTM) in older women with osteoporosis, and to compare their predictive power for osteoporotic fractures (OF).

Methods: In this retrospective study, 96 patients with OF and 107 patients with osteoporosis who were hospitalized in the Department of Orthopedics at the First Affiliated Hospital of Chengdu Medical College were examined from October 2017 to February 2019. All selected patients were divided into either the fracture group (96 cases, 47.3%) or the non-fracture group (107 cases, 52.7%). BMD was measured by dual-energy X-ray absorptiometry (DXA). BTM were detected by electrochemical luminescence: aminoterminal propeptide of type I procollagen (PINP), β-cross-linked C-telopeptide of type I collagen (β-CTX), and molecular fragment of osteocalcin N terminal (N-MID). Bone metabolism-related indicators were detected, including alkaline phosphatase (ALP), calcium (Ca), and phosphorus (P). Independent-samples t-tests were used to compare the measurement data between the two groups, one-way ANOVA to compare the gaps between groups, and binary logistic regression to analyze the correlation of BMD and BTM with OF.

Results: There were no significant differences in age, weight, height, body mass index, age, and time of menopause between the two groups. There were a total of 71 cases (35.0%) in group A (60-70 years), 80 cases (39.4%) in group B (71-80 years), and 52 cases (25.6%) in group C (81-90 years). The fracture group was compared with the non-fracture group for BMD in the lumbar (0.75 ± 0.05 vs 0.88 ± 0.13, 0.75 ± 0.16 vs 0.87 ± 0.09, 0.74 ± 0.21 vs 0.87 ± 0.12 g/cm ; P < 0.05), BMD in the hip (0.62 ± 0.16 vs 0.74 ± 0.14, 0.61 ± 0.15 vs 0.73 ± 0.0, 0.58 ± 0.13 vs 0.73 ± 0.08 g/cm ; P < 0.05), PINP (83.7 ± 5.7 vs 74.8 ± 5.0, 80.7 ± 4.1 vs 72.1 ± 5.1, 81.2 ± 7.0 vs 68.7 ± 6.3 ng/mL, P < 0.05), and β-CTX (829.7 ± 91.5 vs 798.8 ± 52.2, 848.1 ± 71.2 vs 812.4 ± 79.0, 867.3 ± 53.1 vs 849.1 ± 67.2 pg./mL, P < 0.05). N-MID (19.0 ± 6.7 vs 21.3 ± 9.7, 16.2 ± 7.0 vs 18.0 ± 5.3 ng/mL, P < 0.05) in the fracture cases was lower than in the non-fracture cases for groups B and C, and there was statistical significance. Among the fracture cases, PINP in group A was higher than in group B and C, and β-CTX in group C was higher than in group A and B (P < 0.05). There was no significant difference in the ALP, P, and Ca between the two groups (P > 0.05). Binary logistic regression analysis showed that for BMD in the lumbar and hip, β-CTX and OF were significantly correlated (respectively, odds ratio [OR] = -4.182, 95% confidence interval [CI] 1.672-3.448; OR = 6.929, 95% CI 2.586-12.106; OR = 7.572, 95% CI 1.441-3.059), and the differences were statistically significant. PINP and N-MID were correlated with OF (respectively, OR = 4.213, 95% CI 0.978-1.005; OR = 2.510, 95% CI 1.070-1.134, P > 0.05), the difference was not statistically significant.

Conclusion: Osteoporotic older women, with lower bone density and higher β-CTX, are more likely to incur OF. β-CTX is better than BMD at predicting OF and can help in its management and in implementing interventions in high-risk populations.