BackgroundUK guidance on the assessment and management of thyroid disease was set out in NICE guideline NG145 in 2019 and is expected to result in an increase in radioactive iodine (RAI) being offered as a first-line definitive treatment for hyperthyroidism.MethodologyIn this work we analyse longitudinal UK Biobank data to assess all-cause mortality and comorbidity risks associated with the main treatment modalities for 793 participants with hyperthyroidism, specifically antithyroid drugs (ATDs), RAI and thyroidectomy.ResultsParticipants treated with RAI showed reduced all-cause mortality compared with those treated with ATD alone (time to event ratio: 1.8, 95% CI: 0.9-3.6), albeit the result did not reach statistical significance, as did those treated by thyroidectomy (time ratio: 2.0, 95% CI: 1.1-3.9). For treated patients, odds ratios were generally elevated for osteoporosis, cardiovascular events and atrial fibrillation, but again did not reach statistical significance except for those patients treated by ATDs, with an odds ratio for atrial fibrillation of 2.2 (95% CI: 1.2-4.1) versus controls.ConclusionOur findings were consistent with those previously reported in the literature and do not reveal any evidence from the UK Biobank to contradict the safety of RAI being offered as a first-line treatment. The data are also suggestive, however, that treatments do not fully eliminate risks of complications related to hyperthyroidism. This reinforces the need for both clear communication where there may be risks of complications such as osteoporosis as well as clinical support for patients even after definitive treatment.