title: Interest of biochemical markers of bone turnover for long-term prediction of new vertebral fracture in postmenopausal osteoporotic women.
abstract: OBJECTIVE
  To analyse the interest of baseline levels and short-term (3-months) changes in serum osteocalcin (BGP), serum bone-specific alkaline phosphatase (BALP) and urinary C-telopeptide of type I collagen/creatinine ratio (U-CTX) to predict 3-years changes in bone mineral density (BMD) and spinal deformity index (SDI) in postmenopausal osteoporotic women.
  
  
  METHODS
  Data were derived from a cohort of 603 osteoporotic women corresponding to the placebo arm of a 3-years prospective, double-blind study.
  
  
  RESULTS
  Baseline values of BALP, BGP and U-CTX were negatively and significantly correlated with baseline spinal BMD. Significant correlations were also observed between the changes in BMD observed after 36 months at the spine and baseline BALP (r=0.20, P=0.0001), BGP (r=0.09, P=0.05) and U-CTX (r=-0.11, P=0.02). At 3 years, 71 women (15.9%) showed an increase in their SDI, corresponding to the occurrence of at least one new vertebral deformity. Baseline values of the four bone turnover markers (BTM) were not significantly related to the occurrence of new vertebral deformities. However, when considering the changes in the BTM observed after 3-months of follow-up, BGP (P=0.003) and U-CTX (P=0.047) were identified as significant predictors of an increase of SDI. The associated odds ratios (95% confidence interval (CI)) were 10.922 (2.218-53.78) for unit changes of log BGP and 1.369 (1.003-1.867) for unit changes of logU-CTX. The relative risk (RR) (IC 95%) of having a new vertebral fracture over 36 months was 0.31 (0.15-0.65) when being in the lowest quartile of 3-months changes in BGP as compared with the highest.
  
  
  CONCLUSIONS
  We conclude that two sequential measurements of BGP and U-CTX performed at 3-months intervals could be of interest to identify postmenopausal osteoporotic women with the highest risk to present new vertebral deformities.
authors.affiliation: WHO Collaborating Center for Public Health Aspect of Osteoarticular Disorders, Liege, Belgium.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bruyere
authors.forename: Julien
authors.initials: J
authors.lastname: Collette
authors.forename: Pierre
authors.initials: P
authors.lastname: Delmas
authors.forename: Alain
authors.initials: A
authors.lastname: Rouillon
authors.forename: Christian
authors.initials: C
authors.lastname: Roux
authors.forename: Laurence
authors.initials: L
authors.lastname: Seidel
authors.forename: Florent
authors.initials: F
authors.lastname: Richy
authors.forename: Jean Yves
authors.initials: JY
authors.lastname: Reginster
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000469:Alkaline Phosphatase / Q000097:blood; D015415:Biomarkers / Q000032:analysis*; D015519:Bone Density; D016723:Bone Remodeling; D003094:Collagen / Q000652:urine; D024042:Collagen Type I; D003404:Creatinine / Q000652:urine; D005260:Female; D005598:Fractures, Spontaneous / Q000209:etiology*; D006801:Humans; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000378:metabolism*; D010455:Peptides / Q000652:urine; D012307:Risk Factors; D016103:Spinal Fractures / Q000209:etiology*
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D003094:Collagen; D003404:Creatinine; D000469:Alkaline Phosphatase