title: The Effects on the Femoral Cortex of a 24 Month Treatment Compared to an 18 Month Treatment with Teriparatide: A Multi-Trial Retrospective Analysis.
abstract: BACKGROUND
  Teriparatide (TPTD) is an anabolic agent indicated for the treatment of severely osteoporotic patients who are at high risk of fragility fractures. The originally approved duration of TPTD treatment in several regions, including Europe, was 18 months. However, studies of areal bone mineral density (aBMD) showed additional benefit when treatment is continued beyond 18 months, and the drug is currently licenced for 24 months. Improvements in cortical structure at the proximal femur have already been shown in patients given TPTD for 24 months using quantitative computed tomography (QCT). Here, we investigate whether cortical and endocortical trabecular changes differ between an 18- and 24-month treatment.
  
  
  METHODS
  Since an 18- versus 24-month TPTD study using QCT has not been conducted, we studied combined QCT data from four previous clinical trials. Combined femoral QCT data from three 18-month TPTD studies ('18-month group') were compared with data from a fourth 24-month trial ('24-month group'). Cortical parameters were measured over the entire proximal femur which allowed for a comparison of the mean changes as well as a visual comparison of the colour maps of changes after 18 and 24 months TPTD.
  
  
  RESULTS
  For both the combined 18-month group and the 24-month group, overall cortical thickness and endocortical trabecular density increased, while overall cortical bone mineral density decreased. While the changes in the 24-month group were of greater magnitude compared to the 18-month group, the differences were only significant for the endocortical trabecular density (ECTD), corrected for age, weight, femoral neck T-score, total hip T-score and the baseline mean ECTD.
  
  
  CONCLUSIONS
  Although the combination of data from different clinical trials is not optimal, these data support the concept that the duration of TPTD in the 18-24 month phase is of clinical relevance when considering improvement in hip structure.
authors: University of Cambridge, Department of Engineering, Trumpington Street, Cambridge, CB2 1PZ, United Kingdom.
authors: Tristan
authors: T
authors: Whitmarsh
authors: University of Cambridge, Department of Engineering, Trumpington Street, Cambridge, CB2 1PZ, United Kingdom.
authors: Graham M
authors: GM
authors: Treece
authors: University of Cambridge, Department of Engineering, Trumpington Street, Cambridge, CB2 1PZ, United Kingdom.
authors: Andrew H
authors: AH
authors: Gee
authors: University of Cambridge, Department of Medicine, Addenbrooke's Hospital, Cambridge, CB2 0QQ, United Kingdom.
authors: Kenneth E S
authors: KE
authors: Poole
mesh_terms: D000368:Aged; D015519:Bone Density / Q000187:drug effects; D005260:Female; D005269:Femur / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology; D019379:Teriparatide / Q000494:pharmacology* / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D019379:Teriparatide