title: Use of fluroquinolone and risk of Achilles tendon rupture: a population-based cohort study.
abstract: OBJECTIVE
  Several case-control studies have reported that the use of fluoroquinolone increases the risk of rupture of the Achilles tendon. Our aim was to estimate this risk by means of a population-based cohort approach.
  
  
  METHODS
  Data on Achilles tendon ruptures and fluoroquinolone use were retrieved from three population-based databases that include information on residents of Funen County (population: 470,000) in primary and secondary care during the period 1991-1999. A study cohort of all 28,262 first-time users of fluoroquinolone and all incident cases of Achilles tendon ruptures were identified.
  
  
  METHODS
  The incidence rate of Achilles tendon ruptures among users and non-users of fluoroquinolones and the standardised incidence rate ratio associating fluoroquinolon use with Achilles tendon rupture were the main outcome measures.
  
  
  RESULTS
  Between 1991 and 2002 the incidence of Achilles tendon rupture increased from 22.1 to 32.6/100,000 person-years. Between 1991 and 1999 the incidence of fluoroquinolone users was 722/100,000 person-years, with no apparent trend over time. Within 90 days of their first use of fluoroquinolone, five individuals had a rupture of the Achilles tendon; the expected number was 1.6, yielding an age- and sex-standardised incidence ratio of 3.1 [(95% confidence interval (95%CI): 1.0-7.3). The 90-day cumulative incidence of Achilles tendon ruptures among fluoroquinolone users was 17.7/100,000 (95%CI: 5.7-41.3), which is an increase of 12.0/100,000 (95%CI: 0.0-35.6) compared to the background population.
  
  
  CONCLUSIONS
  Fluoroquinolone use triples the risk of Achilles tendon rupture, but the incidence among users is low.
authors.affiliation: Department of Infectious Medicine, Odense University Hospital, 5000, Odense C, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Sode
authors.forename: Niels
authors.initials: N
authors.lastname: Obel
authors.forename: Jesper
authors.initials: J
authors.lastname: Hallas
authors.forename: Annmarie
authors.initials: A
authors.lastname: Lassen
mesh_terms: D000125:Achilles Tendon / Q000293:injuries; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000009:adverse effects*; D002648:Child; D015331:Cohort Studies; D019992:Databases as Topic; D003718:Denmark; D005260:Female; D024841:Fluoroquinolones / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012421:Rupture / Q000139:chemically induced / Q000453:epidemiology; D012737:Sex Factors; D013708:Tendon Injuries / Q000139:chemically induced* / Q000453:epidemiology
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones