Impact of potential pregabalin or duloxetine drug–drug interactions on health care costs and utilization among Medicare members with fibromyalgia

Abstract

Purpose

To examine the impact of newly initiated pregabalin or duloxetine treatment on fibromyalgia (FM) patients’ encounters with potential drug–drug interactions (DDIs), the health care cost and utilization consequences of those interactions, and the impact of treatment on opioid utilization.

Patients and methods

Subjects included those with an FM diagnosis, a pregabalin or duloxetine prescription claim (index event), ≥1 inpatient or ≥2 outpatient medical claims, and ≥12 months preindex and ≥6 postindex enrollment. Propensity score matching was used to help balance the pregabalin and duloxetine cohorts on baseline demographics and comorbidities. Potential DDIs were defined based on Micromedex 2.0 software and were identified by prescription claims.

Results

No significant differences in baseline characteristics were found between matched pregabalin (n=794) and duloxetine cohorts (n=794). Potential DDI prevalence was significantly greater (P<0.0001) among duloxetine subjects (71.9%) than among pregabalin subjects (4.0%). There were no significant differences in all-cause health care utilization or costs between pregabalin subjects with and without a potential DDI. By contrast, duloxetine subjects with a potential DDI had higher mean all-cause costs ($9,373 versus $7,228; P<0.0001) and higher mean number of outpatient visits/member (16.0 versus 13.0; P=0.0009) in comparison to duloxetine subjects without a potential DDI. There was a trend toward a statistically significant difference between pregabalin and duloxetine subjects in their respective pre- versus post-differences in use of ≥1 long-acting opioids (1.6% and 3.4%, respectively; P=0.077).

Conclusion

The significantly higher prevalence of potential DDIs and potential cost impact found in FM duloxetine subjects, relative to pregabalin subjects, underscore the importance of considering DDIs when selecting a treatment.

Keywords:

• Cymbalta
• morphine equivalents
• Lyrica

Acknowledgments

The authors wish to thank Mary Costantino at Comprehensive Health Insights Inc. for assistance with preparation of this manuscript. This research was conceived, funded, and carried out collaboratively by Humana Inc., Pfizer Inc., and Competitive Health Analytics Inc. The research concept was approved by the Joint Research Governance Committee of the Humana–Pfizer Research Collaboration, comprised of Humana Inc. and Pfizer Inc. employees, and plans to publish results were made known prior to commencing the study.

Disclosure

JJE and BTS are employees of Competitive Health Analytics Inc., a wholly owned subsidiary of Humana Inc. CRB is an employee of Humana Inc. BTS is a stockholder of Humana Inc. Competitive Health Analytics Inc. received funding support from Pfizer Inc. in connection with conducting this study and for the development of this article. ABS, JCC, and BP are employees and stockholders of Pfizer Inc. At the time that this research was conducted, LLTE was an employee of Competitive Health Analytics Inc. The authors report no further conflicts of interest with this work.