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Lookup NU author(s): Dr Salman Razvi, Dr Rosie Dew, Dr Scott Wilkes
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Background Subclinical hypothyroidism is diagnosed when serum thyroid stimulating hormone levels are higher whilst free thyroxine levels remain within their respective reference ranges. These reference ranges are uniformly applied in all adults, despite serum thyroid stimulating hormone levels naturally increasing with age. Research has found that mildly elevated thyroid stimulating hormone levels may be associated with some benefits in ageing patients, including reduced mortality and better cardiorespiratory fitness. Levothyroxine is typically prescribed to patients with hypothyroidism, but no conclusive evidence exists on whether levothyroxine therapy is beneficial or detrimental in older subclinical hypothyroid patients. Despite this, prescriptions for levothyroxine are increasing year-on-year. This study aims to determine if receiving levothyroxine affects the cardiovascular and bone health outcomes of subclinical patients in primary care aged 50 years and over. Methods This project includes a retrospective cohort analysis and a target trial emulation study using electronic patient records collected between 2006 and 2021 and recorded in The Health Improvement Network database. The primary outcome of this study is to compare the cardiovascular outcomes of subclinical hypothyroid patients aged over 50 years treated with levothyroxine compared to those untreated. Secondary outcomes are bone health and all-cause mortality outcomes. Descriptive and inferential statistics will both be employed to analyse the data. Secondary analysis will explore confounding factors, including age, sex, smoking status, body mass index, co-morbidities, and levothyroxine dosage. Discussion There needs to be a greater understanding of the potential risks of the current treatment for older patients with subclinical hypothyroidism in a primary care setting. We will investigate the clinical importance of this issue and whether older subclinical hypothyroid patients have poorer outcomes when treated. Clarifying this concern may help address the healthcare resource implications of ageing patients being misclassified as having mild hypothyroidism, as these patients are more likely to repeat their blood tests. This could reduce prescription wastage and improve patient outcomes and quality of life in the ageing population.
Author(s): Holley M, Razvi S, Dew R, Maxwell I, Wilkes S
Publication type: Article
Publication status: Published
Journal: Thyroid Research
Year: 2023
Volume: 16
Online publication date: 13/11/2023
Acceptance date: 16/10/2023
Date deposited: 18/10/2023
ISSN (electronic): 1756-6614
Publisher: BioMed Central Ltd.
URL: https://doi.org/10.1186/s13044-023-00186-0
DOI: 10.1186/s13044-023-00186-0
Data Access Statement: The data that supports the finding of this study are available from THIN a wholly owned subsidiary of Cegedim SA who own the proprietary rights in THIN data. Restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with the permission of THIN. The datasets used during the feasibility study are available from the corresponding author on reasonable request.
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