Comparing common reasons for inpatient and outpatient visits between commercially-insured duloxetine or pregabalin initiators with fibromyalgia

Yang Zhao,¹ Peter Sun,² Mark Bernauer<sup>3

1</sup>Eli Lilly and Company, ²Kailo Research Group, ³OptumInsight, Indianapolis, IN, USA

Background: The purpose of this study was to examine the main reasons for inpatient or outpatient visits after initiating duloxetine or pregabalin.
Methods: Commercially insured patients with fibromyalgia and aged 18–64 years who initiated duloxetine or pregabalin in 2006 with 12-month continuous enrollment before and after initiation were identified. Duloxetine and pregabalin cohorts with similar demographics, pre-index clinical and economic characteristics, and pre-index treatment patterns were constructed via propensity scoring stratification. Reasons for inpatient admissions, physician office visits, outpatient hospital visits, emergency room visits, and primary or specialty care visits over the 12 months post-index period were examined and compared. Logistic regression was used to assess the contribution of duloxetine versus pregabalin initiation to the most common reasons for visits, controlling for cross-cohort differences.
Results: Per the study design, the duloxetine (n = 3711) and pregabalin (n = 4111) cohorts had similar demographics (mean age 51 years, 83% female) and health care costs over the 12-month pre-index period. Total health care costs during the 12-month post-index period were significantly lower for duloxetine patients than for pregabalin patients ($19,378 versus $27,045, P < 0.05). Eight of the 10 most common reasons for inpatient admissions and outpatient hospital (physician office, emergency room, primary or specialty care) visits were the same for both groups. Controlling for cross-cohort differences, duloxetine patients were less likely to be hospitalized due to an intervertebral disc disorder or major depressive disorder, to have a physician office visit due to nonspecific backache/other back/neck pain (NB/OB/NP) disorder, or to go to specialty care due to a soft tissue, NB/OP/NP, or intervertebral disc disorder. However, duloxetine patients were more likely to have a primary care visit due to a soft tissue disorder, essential hypertension, or other general symptoms.
Conclusion: Among similar commercially insured patients with fibromyalgia who initiated duloxetine or pregabalin, duloxetine patients had significantly lower health care costs over the 12-month post-index period. The leading reasons for inpatient or outpatient visits were also somewhat different.

Keywords: duloxetine, pregabalin, inpatient admissions, physician office visits, outpatient hospital visits, emergency room, primary care visits, specialty care visits