Abstract
Clinicians and patients want to know if therapy is working early in their course of treatment. We found that early changes in bone turnover markers at 6 months were associated with long-term changes in bone mineral density but not trabecular bone score at 12 and 24 months. PURPOSE: We sought to examine the association between shorter-term changes in markers of bone turnover and longer-term changes in bone mineral density (BMD) and microstructure in a cohort of frail elderly women with multiple comorbid conditions including osteoporosis. METHODS: We performed a secondary analysis of a 2-year zoledronic acid trial for osteoporosis in 155 women residents of long-term care communities (mean age 86.9 years). We examined the association of the 6-month change in serum C-terminal crosslinking telopeptide of type I collagen (CTX) and serum intact procollagen type I N propeptide (PINP) with the 12- and 24-month changes in BMD at the spine and hip and the trabecular bone score (TBS), an indirect measure of bone microstructure. RESULTS: For every 0.2-ng/ml 6-month CTX decrease, the corresponding increase in spine BMD at 12 and 24 months was 0.2% (p = 0.7210) and 1.1% (p = 0.0396), respectively; total hip BMD 1.1% (p = 0.0279) and 0.9% (p = 0.0716); and femoral neck BMD 1.7% (p = 0.0079) and 0.9% (p = 0.1698). Similarly, for every 20-ng/ml 6-month PINP decrease, the corresponding increase in spine BMD at 12 and 24 months was 0.9% (p = 0.0286) and 1.4% (p = 0.0012), respectively; total hip BMD 1.4% (p = 0.0005) and 1.4% (p = 0.0006); and femoral neck BMD 2.3% (p < 0.0001) and 2.0% (p < 0.0001). Bone marker changes were not consistently associated with TBS changes. CONCLUSION: Shorter-term 6-month changes in bone turnover markers are associated with the long-term changes in BMD over 1-2 years in the spine and hip but not with TBS.