Abstract

Background: Thyroid dysfunction is widespread amongst the older generation, with older females at the highest risk. There is sufficient evidence to suggest that thyroid-stimulating hormone levels naturally increase with age. However, subclinical hypothyroidism diagnosis is made irrespective of age, meaning that older patients are more likely to be prescribed levothyroxine inappropriately. This systematic review and meta-analysis aimed to synthesise previous studies looking at cardiovascular and bone health outcomes of elderly subclinical hypothyroid patients treated with LT4 compared to those untreated.
Methods: PubMed, Embase, Cochrane Library, MEDLINE and Web of Science databases were searched from inception until March 13, 2023. Studies that evaluated the number of cardiovascular and bone health events of patients with subclinical hypothyroidism over 50 years old were selected.
Results: Seven selected articles totalled 5,887 participants, ranging from 185 to 2,034 participants. Six studies reported cardiovascular health outcomes; three studies reported bone health outcomes. A pooled analysis shows no association between adverse cardiovascular effects and levothyroxine use in patients with subclinical hypothyroidism over 65 years of age (pooled odds ratio 0.99; 95% confidence interval 0.86 – 1.15, I2 = 0%). Similarly, there was no association between adverse bone health outcomes and LT4 use in patients with SCH over 65 (pooled OR 0.99; 95% confidence interval 0.52 – 1.88, I2 = 0%).
Conclusions: This systematic review found no association between levothyroxine use and cardiovascular and bone health outcomes in subclinical hypothyroid patients over 65. However, this systematic review did reveal a paucity of studies on this topic, particularly on patients aged between 50 and 65.
Funding: This research is funded by a grant from the National Institute of Health Research Applied Research Collaboration for the North East and North Cumbria.
Registration: PROSPERO number CRD42022308006.