title: Potential drug-drug and drug-condition interactions among fibromyalgia patients initiating pregabalin or duloxetine: prevalence and health care expenditure impact.
abstract: OBJECTIVE
  To quantify the prevalence of potential drug-drug/drug-condition interactions (DDI/DCI) among fibromyalgia patients initiating pregabalin or duloxetine, and to determine the impact of potential DDI/DCI on health care expenditures.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  U.S. clinical practice, as reflected within a large administrative claims database.
  
  
  METHODS
  Fibromyalgia patients newly initiating pregabalin or duloxetine between July 1, 2008 and October 1, 2010 (initiation date = index).
  
  
  METHODS
  Potential DDI measured using clinical software that identifies co-prescription of medications that potentially interact with pregabalin or duloxetine. Potential DCI, drawn from the contraindications and warnings and precautions sections of pregabalin and duloxetine prescribing information, measured using administrative claims-based algorithms. All-cause health care expenditures measured throughout a 6-month postindex period. Analyses included univariate, bivariate, and multivariable statistical approaches.
  
  
  RESULTS
  Seven thousand seven hundred fifty-one pregabalin and 7,785 duloxetine initiators were selected for study: mean age 49 years, 88% female. Only 1.4% of pregabalin initiators had ≥1 potential pregabalin DCI; none had potential pregabalin DDI. In contrast, 67% of duloxetine initiators had potential duloxetine DDI/DCI, driven mostly by potential duloxetine DDI (62% of duloxetine initiators). Compared between pregabalin and duloxetine initiators, differences in the prevalence of potential DDI/DCI were statistically significant (P < 0.001). Multivariable analyses indicated that, among duloxetine initiators, those with potential duloxetine DDI/DCI had postinitiation health care expenditures that were $670 higher (P < 0.001) than those without potential duloxetine DDI/DCI. Among pregabalin initiators, potential pregabalin DDI/DCI were not associated with health care expenditures.
  
  
  CONCLUSIONS
  Among fibromyalgia patients initiating pregabalin or duloxetine, potential duloxetine DDI could be highly prevalent. Among duloxetine initiators, potential duloxetine DDI/DCI were significantly associated with increased health care expenditures.
authors.affiliation: Truven Health Analytics, Bethesda, Maryland, USA.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Johnston
authors.forename: Margarita
authors.initials: M
authors.lastname: Udall
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Cappelleri
authors.forename: Barbara H
authors.initials: BH
authors.lastname: Johnson
authors.forename: George
authors.initials: G
authors.lastname: Shrady
authors.forename: Bong-Chul
authors.initials: BC
authors.lastname: Chu
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Silverman
mesh_terms: D000328:Adult; D000700:Analgesics / Q000191:economics / Q000627:therapeutic use*; D015331:Cohort Studies; D004347:Drug Interactions; D000068736:Duloxetine Hydrochloride; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy*; D005102:Health Expenditures; D006801:Humans; D008297:Male; D008875:Middle Aged; D000069583:Pregabalin; D015995:Prevalence; D012189:Retrospective Studies; D013876:Thiophenes / Q000191:economics / Q000627:therapeutic use*; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives* / Q000191:economics / Q000627:therapeutic use
chemical_list: D000700:Analgesics; D013876:Thiophenes; D000069583:Pregabalin; D005680:gamma-Aminobutyric Acid; D000068736:Duloxetine Hydrochloride
keywords: Comorbidity; Drug Interactions; Fibromyalgia; Health Expenditures