title: Risk of hip, subtrochanteric, and femoral shaft fractures among mid and long term users of alendronate: nationwide cohort and nested case-control study.
abstract: OBJECTIVE
  To determine the skeletal safety and efficacy of long term (≥10 years) alendronate use in patients with osteoporosis.
  
  
  METHODS
  Open register based cohort study containing two nested case control studies.
  
  
  METHODS
  Nationwide study of population of Denmark.
  
  
  METHODS
  61 990 men and women aged 50-94 at the start of treatment, who had not previously taken alendronate, 1996-2007.
  
  
  METHODS
  Treatment with alendronate.
  
  
  METHODS
  Incident fracture of the subtrochanteric femur or femoral shaft (ST/FS) or the hip. Non-fracture controls from the cohort were matched to fracture cases by sex, year of birth, and year of initiation of alendronate treatment. Conditional logistic regression models were fitted to calculate odds ratios with and without adjustment for comorbidity and comedications. Sensitivity analyses investigated subsequent treatment with other drugs for osteoporosis.
  
  
  RESULTS
  1428 participants sustained a ST/FS (incidence rate 3.4/1000 person years, 95% confidence interval 3.2 to 3.6), and 6784 sustained a hip fracture (16.2/1000 person years, 15.8 to 16.6). The risk of ST/FS was lower with high adherence to treatment with alendronate (medication possession ratio (MPR, a proxy for compliance) >80%) compared with poor adherence (MPR <50%; odds ratio 0.88, 0.77 to 0.99; P=0.05). Multivariable adjustment attenuated this association (adjusted odds ratio 0.88, 0.77 to 1.01; P=0.08). The risk was no higher in long term users (≥10 dose years; 0.70, 0.44 to 1.11; P=0.13) or in current compared with past users (0.91, 0.79 to 1.06; P=0.22). Similarly, MPR >80% was associated with a decreased risk of hip fracture (0.73, 0.68 to 0.78; P<0.001) as was longer term cumulative use for 5-10 dose years (0.74, 0.67 to 0.83; P<0.001) or ≥10 dose years (0.74, 0.56 to 0.97; P=0.03).
  
  
  CONCLUSIONS
  These findings support an acceptable balance between benefit and risk with treatment with alendronate in terms of fracture outcomes, even for over 10 years of continuous use.
authors.affiliation: Odense Patient Data Explorative Network, Department of Clinical Research, University of Southern Denmark, J.B. Winsløws Vej 9 A, 3. Sal, DK-5000, Odense, Denmark Department of Medicine, Holbæk Hospital, Smedelundsgade 60, 4300 Holbæk, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Abrahamsen
authors.affiliation: Department of Cardiology, Nephrology and Endocrinology, Hillerød Hospital, Dyrehavevej 29, 3400 Hillerød, Denmark, Pia Eiken Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark, Pia Eiken.
authors.forename: Pia
authors.initials: P
authors.lastname: Eiken
authors.affiliation: Oxford NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeltal Sciences (NDORMS), University of Oxford, Botnar Research Centre, Oxford OX3 7LD, UK Musculoskeletal Research Unit, IMIM-Parc de Salut Mar and RETICEF, Universitat Autònoma de Barcelona and Instituto Carlos III (FEDER Research Funds), Passeig Marítim 25-29, 08003 Barcelona, Spain, Daniel.prietoalhambra@ndorms.ox.ac.uk.
authors.forename: Daniel
authors.initials: D
authors.lastname: Prieto-Alhambra
authors.affiliation: Academic Unit of Bone Metabolism (AUBM), Northern General Hospital and University of Sheffield, Sheffield S5 7AU, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Eastell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000008:administration & dosage / Q000009:adverse effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000009:adverse effects; D016022:Case-Control Studies; D015331:Cohort Studies; D015897:Comorbidity; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005264:Femoral Fractures / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D015994:Incidence; D000069451:Long Term Adverse Effects / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010024:Osteoporosis / Q000188:drug therapy / Q000453:epidemiology; D018570:Risk Assessment
chemical_list: D050071:Bone Density Conservation Agents; D019386:Alendronate