title: A model of BMD changes after alendronate discontinuation to guide postalendronate BMD monitoring.
abstract: BACKGROUND
  Women stopping alendronate are commonly monitored with serial bone mineral density (BMD) measurements, yet no information exists on how frequently or for whom these measurements should be performed.
  
  
  OBJECTIVE
  The objective of the study was to develop a tool to guide post-alendronate BMD monitoring.
  
  
  METHODS
  A predictive model was constructed to estimate the time until a given percentage of women's BMD T-scores drop below a given threshold that indicates a management change (such as retreatment) would be considered. This model was then used to estimate the time it would take for groups of women defined by their baseline BMDs to drop below the given threshold.
  
  
  METHODS
  Data were derived from the Fracture Intervention Trial Long Term Extension (FLEX), the largest multicenter clinical trial of its type to date.
  
  
  METHODS
  Four hundred four women who had received an average of 5.1 years of alendronate during the Fracture Intervention Trial and were subsequently observed for 5 treatment-free years (on placebo) during the FLEX trial were used to estimate the change in BMD over time.
  
  
  RESULTS
  If a management change such as alendronate reinitiation would be considered when BMD T-score drops below -2.5, the model shows that women with total hip BMD greater than -1.9 T-scores at the time of alendronate discontinuation have less than a 20% probability that at follow-up, monitoring BMD will be below the threshold within 5 years. The model performed similarly, and results are provided over a range of management change thresholds from -1.75 to -3 T-scores.
  
  
  CONCLUSIONS
  Using the tool developed in this analysis, it is possible to estimate when BMD repeat measurement after alendronate discontinuation could potentially be useful. Measuring BMD within 5 years after alendronate discontinuation is unlikely to change management for women with total hip BMD 0.6 T-scores above a prespecified retreatment threshold within the range of -1.75 to -3 T-scores.
authors.affiliation: Department of General Internal Medicine (B.M.), San Francisco Veterans Affairs Medical Center, San Francisco, California 94121; Department of Medicine (B.M., D.C.B.), Division of Endocrinology (B.M.), Department of Epidemiology and Biostatistics (E.V., A.V.S., D.C.B., D.M.B.), University of California, San Francisco, San Francisco, California 94117; Academic Unit of Bone Metabolism (R.E.), Department of Human Metabolism, University of Sheffield, Sheffield S10 2JF, United Kingdom; Division of Epidemiology and Community Health (K.E.), Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455; Center for Chronic Disease Outcomes Research (K.E.), Veterans Affairs Health Care System, Minneapolis, Minnesota 55417; and Division of Epidemiology, Department of Family and Preventive Medicine (E.B.-C.), University of California, San Diego, San Diego, California 92093.
authors.forename: Brian
authors.initials: B
authors.lastname: McNabb
authors.forename: Eric
authors.initials: E
authors.lastname: Vittinghoff
authors.forename: Richard
authors.initials: R
authors.lastname: Eastell
authors.forename: Ann V
authors.initials: AV
authors.lastname: Schwartz
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Bauer
authors.forename: Kristine
authors.initials: K
authors.lastname: Ensrud
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Barrett-Connor
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Black
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000494:pharmacology / Q000627:therapeutic use*; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000000981:diagnostic imaging / Q000188:drug therapy*; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000517:prevention & control*; D010384:Pelvic Bones / Q000000981:diagnostic imaging; D011859:Radiography; D028761:Withholding Treatment
chemical_list: D050071:Bone Density Conservation Agents; D019386:Alendronate