Duloxetone treatment patterns and healthcare costs among fibromyalgia patients with medicare supplemental insurance

Abstract

This study examined how treatment patterns and healthcare costs differed by duloxetine maximum titrated dosage among elderly fibromyalgia patients. Patients aged 65+ with Medicare supplemental insurance who initiated duloxetine in 2006 were examined using medical and pharmacy claims data. Initiation was defined as no duloxetine coverage over the prior 90 days, with the first initiation date as the index date. All patients included had continuous 12 months enrollment prior to and following the index date and at least 30 days of duloxetine supply in the 12-month post-index period. Individuals with a diagnosis of diabetic peripheral neuropathic pain or depression during the 12-month pre-index period were excluded. Duloxetine patients were grouped into three cohorts based on maximum dosage: <60mg, 60mg, and >60mg. Duloxetine adherence (measured by medication possession ratio ≥0.8), average daily dose (ADD), and index dose were examined. The association between maximum dosage and healthcare costs was assessed via regression models. A total of 566 duloxetine patients were included, with 160, 341 and 65 in the <60mg, 60mg, and >60mg cohorts, respectively. On average, patients in the <60mg, 60mg, and >60mg cohorts were on maximum dosage for 112, 177, and 100 days and took 17, 26, and 113 days to reach their maximum dosage, respectively. Duloxetine patients with lower maximum dosage had worse adherence (17% vs. 36% vs. 51%), lower index dose (29.5mg vs. 53.8mg vs. 67.9mg), and lower ADD (29.6mg vs. 56.3mg vs. 80.1mg). Adjusting for differences in demographics and comorbidities, patients in the <60mg cohort had lower total healthcare costs (-$3,954, p<0.05) than patients in 60mg cohort, primarily due to inpatient costs (-$5,256, p<0.05). Among elderly fibromyalgia patients initiated on duloxetine in 2006, those with lower duloxetine maximum dosage had worse adherence, lower index dosage and ADD, and lower healthcare costs. (Funding provided by Eli Lilly and Company.)