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Comparative Study
. 2020 Sep 1;3(9):e2017645.
doi: 10.1001/jamanetworkopen.2020.17645.

Comparative Effectiveness of Generic vs Brand-Name Levothyroxine in Achieving Normal Thyrotropin Levels

Juan P Brito  1 , Joseph S Ross  2   3   4 , Lindsey Sangaralingham  5 , Sarah K Dutcher  6 , David J Graham  6 , Zhong Wang  7 , Yute Wu  8 , Xiaoxi Yao  5   9 , Robert C Smallridge  10 , Victor Bernet  10 , Nilay D Shah  5   9   11 , Kasia J Lipska  4   12
Affiliations
Comparative Study

Comparative Effectiveness of Generic vs Brand-Name Levothyroxine in Achieving Normal Thyrotropin Levels

Juan P Brito et al. JAMA Netw Open. .

Abstract

Importance: Whether the use of generic vs brand levothyroxine affects thyrotropin levels remains unclear.

Objective: To compare the effectiveness of generic vs brand levothyroxine in achieving and maintaining normal thyrotropin levels among new users.

Design, setting, and participants: This retrospective, 1:1 propensity score-matched longitudinal cohort study used the OptumLabs Data Warehouse administrative claims database linked to laboratory results from commercially insured and Medicare Advantage enrollees throughout the United States. Eligible patients were adults (aged ≥18 years) with thyrotropin levels ranging from 4.5 to 19.9 mIU/L who initiated use of generic or brand-name levothyroxine from January 1, 2008, to October 1, 2017. Data were analyzed from August 13, 2018, to October 25, 2019.

Exposure: Patients received generic or brand-name levothyroxine.

Main outcomes and measures: Proportion of patients with normal vs markedly abnormal thyrotropin levels (<0.1 or >10 mIU/L) within 3 months and with stable thyrotropin levels within 3 months after the thyrotropin value fell into the normal range.

Results: A total of 17 598 patients were included (69.0% female; 74.0% White; mean [SD] age, 55.1 [16.0] years), of whom 15 299 filled generic and 2299 filled brand-name levothyroxine prescriptions during the study period. Among 4570 propensity score-matched patients (mean [SD] age, 50.3 [13.8] years; 3457 [75.6%] female; 3510 [76.8%] White), the proportion with normal thyrotropin levels within 3 months of filling levothyroxine prescriptions was similar for patients who received generic vs brand-name levothyroxine (1722 [75.4%; 95% CI, 71.9%-79.0%] vs 1757 [76.9%; 95% CI, 73.4%-80.6%]; P = .23), as was the proportion with markedly abnormal levels (94 [4.1%; 95% CI, 3.4%-5.0%] vs 88 [3.9%; 95% CI, 3.1%-4.7%]; P = .65). Among 1034 propensity score-matched patients who achieved a normal thyrotropin value within 3 months of initiation of levothyroxine, the proportion maintaining subsequent normal thyrotropin levels during the next 3 months was similar for patients receiving generic vs brand-name levothyroxine (427 [82.6%] vs 433 [83.8%]; P = .62).

Conclusions and relevance: Initiation of generic vs brand-name levothyroxine formulations was associated with similar rates of normal and stable thyrotropin levels. These results suggest that generic levothyroxine as initial therapy for mild thyroid dysfunction is as effective as brand-name levothyroxine.

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Conflict of interest statement

Conflict of Interest Disclosures: Dr Brito reported receiving support from the Karl-Erivan Haub Family Career Development Award in Cancer Research at Mayo Clinic in Rochester and grants from the US Food and Drug Administration (FDA) during the conduct of the study. Dr Ross reported receiving grants from the FDA during the conduct of the study and research support through Yale University from Johnson & Johnson, Medtronic, Inc, the FDA (grant U01FD004585), the Blue Cross Blue Shield Association, Centers for Medicare & Medicaid Services (CMS) (grant HHSM-500-2013-13018I), the Agency for Healthcare Research and Quality (AHRQ) (grant R01HS022882), the National Heart, Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH) (grant R01HS025164), the Laura and John Arnold Foundation, and Medical Device Innovation Consortium outside the submitted work. Ms Sangaralingham reported receiving grants from the FDA during the conduct of the study. Dr Smallridge reported receiving support from the Alfred D. and Audrey M. Petersen Professorship in Cancer Research. Dr Shah reported receiving research support through Mayo Clinic from the Centers of Medicare and Medicaid Innovation, AHRQ (grants R01HS025164, R01HS025402, R03HS025517, and U19HS024075), the NHLBI of the NIH (grants R56HL130496 and R01HL131535), the National Science Foundation, and the Patient Centered Outcomes Research Institute to develop a Clinical Data Research Network. Dr Lipska reported receiving support from CMS and the National Institute on Aging and the American Federation of Aging Research through Paul Beeson Career Development Award K23AG048359. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Study Population
aThe study population was limited to those 18 years or older with coverage 365 days before and 90 days after prescription date, prescriptions starting after 2008, prescriptions for levothyroxine, and thyrotropin measurements at baseline and 3 months. bPatients with thyroid cancer, hypopituitarism, thyroiditis, or hyperthyroidism, who were pregnant or nonadherent, or who switched formulations were excluded.
Figure 2.
Figure 2.. Study Outcomes
See this image and copyright information in PMC

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