(398) Potential drug-drug interactions and opioid use among Medicare members with fibromyalgia and newly initiated on pregabalin or duloxetine

Abstract

This study examined the prevalence of potential drug-drug interactions (pDDIs), the impact of pDDIs on healthcare utilization and costs, and post-index use of opioid analgesics among fibromyalgia (FM) Medicare members newly initiated on pregabalin (PGB) or duloxetine (DLX). Members included those with a PGB or DLX prescription claim between 07/01/2008-06/30/2012 (index event), ≥1 inpatient or ≥2 outpatient medical claims with FM diagnosis between 01/01/2008-12/31/2012, and ≥12 months pre-index and ≥6 post-index enrollment. Propensity score matching (nearest neighbor approach) was used to help balance the PGB and DLX cohorts on baseline demographic and comorbidity characteristics. pDDIs were defined based on Micromedex 2.0 software and were identified by prescription claims. Six month post-index healthcare utilization and costs were measured by medical and pharmacy claims. Continuous and categorical comparisons were conducted using Wilcoxon rank sum tests and chi-square tests, respectively. No significant differences in baseline demographics or comorbidities were found between matched PGB (n=794) and DLX members (n=794). pDDI prevalence was significantly greater (p<0.0001) among DLX members (71.9%) than among PGB members (4.0%). There were no significant differences in all-cause healthcare utilization or costs between PGB members with and without a pDDI. By contrast, DLX members with a pDDI had higher median all-cause costs ($4,719 versus $3,519; p<0.0001) and median number of outpatient visits/member (14.0 versus 12.0; p=0.0009) in comparison to DLX members without a pDDI. Over 12% of potential DLX interactions involved anticoagulants (n=268). There was a trend toward a difference between PGB and DLX members in their respective pre-versus-post differences in use of long-acting opioids (1.6% and 3.4%, respectively; p=0.077). The significantly higher prevalence of pDDIs and potential cost impact found in FM DLX users, relative to PGB, underscore the importance of considering DDIs when selecting a treatment. This study was funded by Pfizer Inc and Humana Inc. This study examined the prevalence of potential drug-drug interactions (pDDIs), the impact of pDDIs on healthcare utilization and costs, and post-index use of opioid analgesics among fibromyalgia (FM) Medicare members newly initiated on pregabalin (PGB) or duloxetine (DLX). Members included those with a PGB or DLX prescription claim between 07/01/2008-06/30/2012 (index event), ≥1 inpatient or ≥2 outpatient medical claims with FM diagnosis between 01/01/2008-12/31/2012, and ≥12 months pre-index and ≥6 post-index enrollment. Propensity score matching (nearest neighbor approach) was used to help balance the PGB and DLX cohorts on baseline demographic and comorbidity characteristics. pDDIs were defined based on Micromedex 2.0 software and were identified by prescription claims. Six month post-index healthcare utilization and costs were measured by medical and pharmacy claims. Continuous and categorical comparisons were conducted using Wilcoxon rank sum tests and chi-square tests, respectively. No significant differences in baseline demographics or comorbidities were found between matched PGB (n=794) and DLX members (n=794). pDDI prevalence was significantly greater (p<0.0001) among DLX members (71.9%) than among PGB members (4.0%). There were no significant differences in all-cause healthcare utilization or costs between PGB members with and without a pDDI. By contrast, DLX members with a pDDI had higher median all-cause costs ($4,719 versus $3,519; p<0.0001) and median number of outpatient visits/member (14.0 versus 12.0; p=0.0009) in comparison to DLX members without a pDDI. Over 12% of potential DLX interactions involved anticoagulants (n=268). There was a trend toward a difference between PGB and DLX members in their respective pre-versus-post differences in use of long-acting opioids (1.6% and 3.4%, respectively; p=0.077). The significantly higher prevalence of pDDIs and potential cost impact found in FM DLX users, relative to PGB, underscore the importance of considering DDIs when selecting a treatment. This study was funded by Pfizer Inc and Humana Inc.