title: Reduction of urinary levels of N-telopeptide correlates with treatment compliance in women with postmenopausal osteoporosis receiving alendronate.
abstract: OBJECTIVE
  The aim of this study was to assess the factors associated with the effectiveness of treatment with alendronate (ALN) quantified by a reduction in urinary excretion of N-telopeptide (NTx).
  
  
  METHODS
  The study is an observational, prospective, multicenter trial, with a 6-month follow-up. Postmenopausal osteoporotic women (densitometric criteria), who initiated treatment with ALN (70 mg/weekly) without previous treatment with antiresorptive agents (12 month) and calcitonin (6 month), were included. The assessment of NTx levels (nmol bone collagen equivalents/mmol creatinine) in the urine was performed at baseline and after completion of follow-up. A logistic regression model included "achieving a reduction in urinary NTx of at least 30% (minimal clinically significant change [MCSC])" as a dichotomous dependent variable and the following as independent variables: baseline urinary NTx levels, treatment compliance, years since diagnosis of menopause, ALN treatment duration, and treatment with calcium and vitamin D. Treatment compliance was assessed as the percentage of days of medication prescribed as a function of the time between the beginning and end of treatment. Good compliance was defined as a percentage between 80% and 120%.
  
  
  RESULTS
  The variables that reached statistical significance were baseline urinary NTx values (odds ratio, 1.052; 95% CI, 1.025-1.079) and compliance (odds ratio, 3.9; 95% CI, 1.5-10.1). Therefore, the women with good treatment compliance were almost 4 times more likely to achieve an MCSC in NTx levels, and the raise in one unit of urinary NTx baseline values increased by 5% of the probability of achieving MCSC.
  
  
  CONCLUSIONS
  Treatment with ALN (70 mg/week) in women with postmenopausal osteoporosis effectively reduces the urinary excretion of the bone turnover biomarker NTx. The probability of achieving a clinically significant reduction is greater in those women with higher baseline levels of NTx and in women who comply with treatment.
authors.affiliation: Instituto Palacios, Madrid, Spain. jpalacios@institutopalacios.com
authors.forename: Santiago
authors.initials: S
authors.lastname: Palacios
authors.forename: José Luis
authors.initials: JL
authors.lastname: Neyro
authors.forename: Javier
authors.initials: J
authors.lastname: Ferrer
authors.forename: José
authors.initials: J
authors.lastname: Villero
authors.forename: Enrique
authors.initials: E
authors.lastname: Cañada
authors.forename: Esther
authors.initials: E
authors.lastname: Redondo
authors.forename: Ma Teresa
authors.initials: MT
authors.lastname: Caloto
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Nocea
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000627:therapeutic use*; D015519:Bone Density; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D024042:Collagen Type I / Q000652:urine*; D005260:Female; D006801:Humans; D055118:Medication Adherence; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy* / Q000652:urine; D010455:Peptides / Q000652:urine*; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D050071:Bone Density Conservation Agents; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D019386:Alendronate