Trends and Components of Thyroid Status Evaluation in Commercially Insured Adults in the United States, 2006-2020

Abstract Context Thyroid-stimulating hormone (TSH) is one of the most ordered laboratory tests. Objective Determine trends of TSH testing rates and components of thyroid function testing. Methods This was a retrospective analysis of adults 18-64 years old without evidence of thyroid disease with at least 365 days of continuous enrollment between 2006 and 2020 in the IBM MarketScan Claims Database. The main outcome measures were trends of TSH tests/1000 eligible patient-months stratified by age, sex, and region and composition of thyroid function testing. Results Among 67 353 280 patients meeting eligibility criteria, we identified 25 606 518 TSH tests and 15 138 211 patients with ≥1 TSH test. Patients contributing an episode of TSH testing were most commonly 45-54 years old (29.8%) and female (63.6%). TSH testing rates remained consistent throughout the study period with 11.4 and 11.7 TSH tests/1000 person-months in the first and last study months, respectively (mean 12.2 TSH tests/1000 person-months). TSH testing rates dropped sharply in the spring of 2020 (4.2 TSH tests/1000 person-months). Females showed a nearly 2-fold higher rate of TSH testing than males (16.1 TSH tests/1000 person-months vs 8.6 TSH tests/1000 person-months). TSH testing rates increased with age (8.2 TSH tests/1000 person-months among individuals 18-34 years old vs 15.4 TSH tests/1000 person-months among individuals 55-64 years old). No difference in TSH testing rates was noted between regions. Thyroid function testing episodes included only TSH in most cases (70.8%). Conclusion TSH testing rates among commercially insured individuals without known thyroid disease appears stable over time, with higher frequency in females and with increasing age.