title: Effectiveness of risedronate and alendronate on nonvertebral fractures: an observational study through 2 years of therapy.
abstract: This observational study showed that after 2 years, both risedronate and alendronate lowered the risk of hip and nonvertebral fractures compared with patients filling in a single bisphosphonate prescription.
  
  
  BACKGROUND
  Post hoc analyses of the placebo-controlled trials suggested earlier effects for risedronate (6-12 months) than for alendronate (18-24 months). The present study extends our 1-year observational data that confirmed an earlier fracture reduction with risedronate and evaluated the absolute and relative effectiveness of alendronate and risedronate in clinical practice over 2 years.
  
  
  METHODS
  We observed three cohorts of women aged 65 years and older who initiated once-a-week dosing of bisphosphonate therapy; (1) patients adherent to alendronate (n = 21,615), (2) patients adherent to risedronate (n = 12,215), or (3) patients filling only a single bisphosphonate prescription (n = 5,390) as a referent population. Proportional hazard modeling compared the incidence of hip and nonvertebral fractures among the cohorts over 2 years after the initial prescription.
  
  
  RESULTS
  In this cohort, we previously showed at 12 months a significant reduction of hip and nonvertebral fractures with risedronate but not with alendronate. At the end of 2 years, the cumulative incidence of hip fractures in the referent cohort was 1.9 %, and incidence of nonvertebral fractures was 6.3 %. Relative to the referent, 6 months after initiating therapy and continuing through 2 years, both risedronate and alendronate cohorts had approximately a 45 % lower incidence of hip fractures and a 30 % lower incidence of nonvertebral fractures.
  
  
  CONCLUSIONS
  These observations suggest that both risedronate and alendronate are effective at reducing the risk of hip and nonvertebral fracture after 2 years of treatment and support the post hoc analyses of placebo-controlled trials indicating an earlier effect of risedronate.
authors.affiliation: Helen Hayes Hospital, 51-55 Route 9W, West Haverstraw, NY 10993, USA. lindsayr@helenhayeshosp.org
authors.forename: R
authors.initials: R
authors.lastname: Lindsay
authors.forename: N B
authors.initials: NB
authors.lastname: Watts
authors.forename: J L
authors.initials: JL
authors.lastname: Lange
authors.forename: P D
authors.initials: PD
authors.lastname: Delmas
authors.forename: S L
authors.initials: SL
authors.lastname: Silverman
mesh_terms: D000368:Aged; D019386:Alendronate / Q000008:administration & dosage / Q000627:therapeutic use*; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D004164:Diphosphonates / Q000008:administration & dosage / Q000627:therapeutic use; D004334:Drug Administration Schedule; D012968:Etidronic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000188:drug therapy / Q000453:epidemiology; D058866:Osteoporotic Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D000068296:Risedronic Acid; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D016903:Drug Monitoring
chemical_list: D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D000068296:Risedronic Acid; D012968:Etidronic Acid; D019386:Alendronate