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Endocrinologists more likely to prescribe brand-name thyroid hormone drugs

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February 1, 2019

Endocrinologists are more likely to prescribe brand-name thyroid hormone drugs vs. general practitioners, despite an overall increase in the dispensing of generic thyroid hormone therapies over 10 years, according to findings published in The Journal of Clinical Endocrinology & Metabolism.

In an analysis of data from three distinct beneficiary populations — adults covered by commercial insurers, Medicare Advantage and Medicare Part D — the researchers also noted that the trend of increased generic thyroid hormone prescriptions was driven primarily by declining brand-name levothyroxine prescribing in favor of increasing generic levothyroxine dispensing.

“Certain patient characteristics, including female sex, white race and greater household income, were consistently associated with higher rates of brand-name thyroid hormone prescribing,” Joseph S. Ross, MD, MHS, associate professor of medicine and public health at Yale University School of Medicine, and colleagues wrote. “One might consider these predictors of brand-name drug use to not be modifiable. However, these patient characteristics may be useful for purposes of targeting patient information and other educational interventions to achieve a higher proportion of generic drug dispensing and ensuring patients are using the lowest-cost available therapies when appropriate.”

In a retrospective, cross-sectional analysis, Ross and colleagues analyzed pharmacy claims data from OptumLabs Data Warehouse, a database that includes individuals with insurance coverage through commercial, Medicare Advantage and Medicare Part D health plans. The researchers analyzed data for any thyroid hormone drug filled by an adult patient between 2007 and 2016, including all single-agent drugs with levothyroxine, liothyronine, liotrix and desiccated thyroid extract.

The researchers identified 96,354,600 pharmacy fills for thyroid hormone drugs among 4,228,174 patients, suggesting that thyroid hormone prescriptions were filled by 6.8% of the beneficiary population at least once during the study period. Between 2007 and 2016, the annual number of thyroid hormone pharmacy fills increased 30.4% and the number of unique patients filling a prescription rose 64.7%.

Across all health plans, 80% of prescriptions were filled by women and 70% of fills were prescribed by general practitioners. Most drug fills were for generic levothyroxine (73.6%), followed by brand-name levothyroxine (23.4%). Generic thyroid hormone drug dispensing increased from 59.8% of all fills in 2007 to 84.9% in 2016, according to researchers. Medicare Advantage and Medicare Part D beneficiaries were more likely to fill prescriptions for generic thyroid drugs vs. those who were commercially insured.

For the three beneficiary populations, older adults were more likely to fill prescriptions for generic thyroid hormone drugs, whereas women and those receiving prescriptions from endocrinologists were more likely to fill prescriptions for brand-name drugs (P < .001 for all), according to researchers.

Researchers observed the largest effect estimate for the association between brand-name thyroid hormone treatment and having a prescriber specialty of endocrinology, both for the commercially insured cohort (OR = 3.28; 95% CI, 3.25-3.32) and the Medicare Advantage cohort (OR = 4.32; 95% CI, 4.21-4.44).

“In contrast, as compared to 2007, thyroid hormone treatment fills in each subsequent year through 2017 were less likely to be for brand-name therapies,” the researchers wrote. – by Regina Schaffer

Disclosures: Ross reports he has received research support through Yale University from the Agency for Healthcare Research and Quality, the Blue Cross Blue Shield Association, CMS, FDA, Johnson & Johnson, Medtronic and the NIH. Please see the study for all other authors’ relevant financial disclosures.

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