title: The effect of obesity on antibiotic treatment failure: a historical cohort study.
abstract: OBJECTIVE
  Obesity, a major health issue, is also an important risk factor for infections. Evidence demonstrates that excess weight affects the disposition of antibiotics but little work has been done to explore if this results in antibiotic treatment failure (ATF). ATF has serious adverse health outcomes and may increase treatment resistance. Given that obese patients often have other health issues, it is important to determine if excess weight independently increases the likelihood of ATF.
  
  
  METHODS
  Consenting patients (N = 18 014), randomly sampled from Santé Québec Health surveys (1992, 1998), were linked with administrative health databases. Patients were within the normal, overweight, and obese weight categories aged 20-79 years old, receiving at least one course of antibiotic therapy from the survey date until December 2005. ATF was defined as any additional antibiotic prescriptions or hospitalizations for infections within the 30 days after initial therapy. Logistic regression was used to assess the impact of excess weight on ATF after adjusting for patient characteristics, comorbidities, history of antibiotic use, antibiotic resistance, and flu season.
  
  
  RESULTS
  Of the final sample size (N = 6 179), 39.0% were overweight and 21.4% were obese. The most frequently prescribed antibiotics were amoxicillin (16.0%), ciprofloxacin (9.2%), phenoxymethylpenicillin (8.8%), trimethroprim/sulfamethoxazole (8.6%), and clarithromycin (8.5%). ATF occurred in 828 (13.4%) of the 6 179 study patients. Obesity was a significant predictor of ATF (adjusted OR 1.26; 95% CI 1.03-1.52).
  
  
  CONCLUSIONS
  Obesity is a significant risk factor for ATF, and this association may be due to the current "one size fits all" dosing strategy, which warrants further investigation.
authors.affiliation: McGill University, Department of Family Medicine, Montreal, Quebec, Canada.
authors.forename: Cristina
authors.initials: C
authors.lastname: Longo
authors.forename: Gillian
authors.initials: G
authors.lastname: Bartlett
authors.forename: Brenda
authors.initials: B
authors.lastname: Macgibbon
authors.forename: Nancy
authors.initials: N
authors.lastname: Mayo
authors.forename: Ellen
authors.initials: E
authors.lastname: Rosenberg
authors.forename: Lyne
authors.initials: L
authors.lastname: Nadeau
authors.forename: Stella S
authors.initials: SS
authors.lastname: Daskalopoulou
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D001424:Bacterial Infections / Q000150:complications* / Q000188:drug therapy* / Q000453:epidemiology; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology; D017891:Pharmacoepidemiology; D012307:Risk Factors; D012959:Socioeconomic Factors; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents
keywords: antibiotics; infection; obesity; pharmacoepidemiology; treatment failure