The economic impact of switching from Synthroid for the treatment of hypothyroidism.

AIMS: To compare hypothyroidism-related costs for patients who continuously used Synthroid and patients who switched from Synthroid to alternative therapies.

MATERIALS AND METHODS: Truven's Health Analytics MarketScan Commercial Claims and Encounters database from January 1, 2007 to June 30, 2014 was queried for US adults diagnosed with hypothyroidism who initiated Synthroid and adhered to such therapy for at least 6 months. Propensity score matching matched continuous users of Synthroid to patients who switched from Synthroid to alternative levothyroxine agents. Kruskal-Wallis tests assessed differences between the matched cohorts in several categories of costs, including disease-related drug costs, non-drug medical costs, and total direct medical costs.

RESULTS: There were 10,159 individuals included in the study, with 7,991 continuous users of Synthroid and 2,168 switchers. After matching (n = 2,052 for each cohort), continuous use of Synthroid was associated with significantly lower hypothyroidism-related non-drug medical costs ($595 vs $1,023; p = .003) and reduced hypothyroidism-related total medical costs ($757 vs $1,132; p = .010), despite being associated with significantly higher drug costs ($161 vs $109; p < .001). Hypothyroidism-related total medical costs rose as the number of switches of hypothyroidism treatment increased, with continuous users having significantly lower hypothyroidism-related total medical costs ($757) compared with patients who switched twice ($1,179; p = .001) or three or more times ($1,268; p = .004).

LIMITATIONS: The analyses focused on continuously insured patients who were adherent to Synthroid for at least 6 months and results may not be generalizable. The reliance on claims data does not allow for clinical examination of hypothyroidism or inclusion of some factors that may be associated with outcomes. The analyses assume that all prescriptions filled are taken as prescribed.

CONCLUSIONS: Results indicate that there are significant direct economic healthcare costs associated with switching from Synthroid to alternative levothyroxine therapies, and that these costs increase as patients switch therapies more frequently.