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Cited by 17Thyroid Disorders and TreatmentsThyroid and Parathyroid SurgeryPharmaceutical Practices and Patient Outcomes

Prevalence and factors associated with chronic use of levothyroxine: A cohort study

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Janett-Pellegri, Camilla, Wildisen, Lea, Feller, Martin, Del Giovane, Cinzia, Moutzouri, Elisavet, Grolimund, Oliver, Walter, Patrick, Waeber, Gérard +3 more·2021·PLOS ONE
DOI 10.1371/journal.pone.0261160PMC PMC8687586
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Abstract

Importance: Levothyroxine prescriptions are rising worldwide. However, there are few data on factors associated with chronic use. Objective: To assess the prevalence of chronic levothyroxine use, its rank among other chronic drugs and factors associated with chronic use. To assess the proportion of users outside the therapeutic range of thyroid-stimulating hormone (TSH). Design: Cohort study (CoLaus|PsyCoLaus) with recruitment from 2003 to 2006. Follow-ups occurred 5 and 10 years after baseline. Participants: A random sample of Lausanne (Switzerland) inhabitants aged 35–75 years. Main outcomes: We evaluated the prevalence of chronic levothyroxine use and we then ranked it among the other most used chronic drugs. The ranking was compared to data from health insurance across the country. We assessed the association between each factor and chronic levothyroxine use in multivariable logistic regression models. The proportion of chronic levothyroxine users outside the usual TSH therapeutic range was assessed. Results: 4,334 participants were included in the analysis (mean±SD age 62.8±10.4 years, 54.9% women). 166 (3.8%) participants were chronic levothyroxine users. Levothyroxine was the second most prescribed chronic drug after aspirin in the cohort (8.2%) and the third most prescribed when using Swiss-wide insurance data. In multivariable analysis, chronic levothyroxine use was associated with increasing age [odds ratio 1.03, 95% confidence interval 1.01–1.05 per 1-year increase]; female sex [11.87 (5.24–26.89)]; BMI [1.06 (1.02–1.09) per 1-kg/m2 increase]; number of concomitant drugs [1.22 (1.16–1.29) per 1-drug increase]; and family history of thyroid pathologies [2.18 (1.37–3.48)]. Among chronic levothyroxine users with thyroid hormones assessment (n = 157), 42 (27%) were outside the TSH therapeutic range (17% overtreated and 10% undertreated). Conclusions: In this population-based study, levothyroxine ranked second among chronic drugs. Age, female sex, BMI, number of drugs and family history of thyroid pathologies were associated with chronic levothyroxine use. More than one in four chronic users were over- or undertreated.

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  • Nine studies over nearly 30 years across five different countries show that only 50%-70% of patients prescribed levothyroxine maintain serum TSH within reference range.

    “nine studies over nearly 30 years across five different countries show that only 50% -70% of patients prescribed levothyroxine maintain serum TSH within reference range. 20,30 -34”

    From Use of liothyronine (T3) in hypothyroidism: Joint British Thyroid Association/Society for endocrinology consensus statement (2023) · cites this paper as [32]

    The Discussion (‘Proportion of levothyroxine users within the therapeutic range’; page unavailable) reports substantial overtreatment in other studies, including 41% among older US patients. But this paper does not establish that nine studies spanning nearly 30 years and five countries found 50%–70% within range. Its own finding is that 27% of chronic users were outside the therapeutic range—approximately 73% within it. (LLM, conf=0.84)

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  • Levothyroxine has a narrow therapeutic index, and both under-treatment (TSH above reference range) and over-treatment (TSH below reference range) are common, with cross-sectional studies consistently showing that 30%-50% of patients on levothyroxine have TSH values outside of the laboratory reference range.

    “Levothyroxine has a narrow therapeutic index, however, and both under -treatment (TSH above the reference range) and over -treatment (TSH below the reference range) are common, with cross -sectional studies consistently showing that 30% -50% of patients on levothyroxine have TSH values outside of the laboratory reference range. 20,30 -34,65”

    From Use of liothyronine (T3) in hypothyroidism: Joint British Thyroid Association/Society for endocrinology consensus statement (2023) · cites this paper as [32]

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Research works printed but not linked: 1

  1. [30]M A. Medicines Use and Spending in the U.S.: A Review of 2016 and Outlook to 2021 2017 [cited 2018 March, 19]. https://www.iqvia.com/-/media/iqvia/pdfs/institute-reports/medicines-use-and-spending-in-the-us.pdf?&_=1552986119356.

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Authors
Janett-Pellegri, C., Wildisen, L., Feller, M., Del Giovane, C., Moutzouri, E., Grolimund, O., Walter, P., Waeber, G., Marques-Vidal, P., Vollenweider, P., & Rodondi, N.
Affiliations
  • University of Bern (CH)
  • Centre Hospitalier Universitaire Vaudois (CH)
Corresponding author
Rodondi, Nicolas
ORCID
Venue
PLOS ONE
Publisher
Public Library of Science (PLoS)
Published
2021-12-20
Volume
16
Issue
12
Pages
e0261160
ISSN
1932-6203 (ISSN-L)
DOI
10.1371/journal.pone.0261160
PMC
PMC8687586
OpenAlex
W4200281330
Cited by
17
References
37
Citations by year
2026: 4 · 2025: 5 · 2024: 3 · 2023: 5
FWCI
1.49
Type
journal article
Language
en
Open access
Licence
Locations
  • PLoS ONE (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
  • Bern Open Repository and Information System (University of Bern) (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • IRIS (submittedVersion, cc-by)
  • IRIS UNIMORE (University of Modena and Reggio Emilia) (submittedVersion, cc-by)
  • SERVAL (Université de Lausanne) (submittedVersion, cc-by)
  • Open Access CRIS of the University of Bern
Funders
  • Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (SNSF 320030-172676, SNSF 32003B-173092, 3200B0–105993, 3200B0-118308, 33CSCO-122661, 33CS30-139468, 33CS30-148401, 32473B-182210)
  • Université de Lausanne
  • SASIS
  • santésuisse
  • GlaxoSmithKline
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Thyroid Disorders and Treatments
  • Health Sciences › Medicine › Surgery › Thyroid and Parathyroid Surgery
  • Health Sciences › Medicine › Geriatrics and Gerontology › Pharmaceutical Practices and Patient Outcomes
Keywords
levothyroxine, chronic drug use, thyroid hormone replacement, thyroid-stimulating hormone, overtreatment, undertreatment, prevalence, risk factors, body mass index, polypharmacy, family history of thyroid disease, prescribing patterns, aspirin comparison, older adults, women
MeSH terms
Adult, Aged, Diabetes Mellitus, Drug Utilization, Female, Humans, Hypertension, Male, Middle Aged, Thyroid Gland, Thyroxine, Cohort Studies

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