Open AccessPotential Drug–Drug and Drug–Condition Interactions among Fibromyalgia Patients Initiating Pregabalin or Duloxetine: Prevalence and Health Care Expenditure Impact
Author(s) -
Johnston Stephen S.,
Udall Margarita,
Cappelleri Joseph C.,
Johnson Barbara H.,
Shrady George,
Chu BongChul,
Silverman Stuart L.
Publication year - 2014
Publication title -
pain medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.893
H-Index - 97
eISSN - 1526-4637
pISSN - 1526-2375
DOI - 10.1111/pme.12330
Subject(s) - duloxetine , pregabalin , fibromyalgia , medicine , drug , tramadol , health care , analgesic , psychiatry , alternative medicine , pathology , economics , economic growth
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. Design Retrospective cohort study. Setting U . S . clinical practice, as reflected within a large administrative claims database. Subjects Fibromyalgia patients newly initiating pregabalin or duloxetine between July 1, 2008 and October 1, 2010 (initiation date = index). Outcome Measures 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.