Endocrine Abstracts

Introduction: Between 5-10% of patients with hypothyroidism treated with levothyroxine (T4) continue to experience profound symptoms, despite achieving free T4/thyroid stimulating hormone concentrations within reference range. Liothyronine is sometimes added to levothyroxine, but its use is controversial due to uncertainties in clinical/cost effectiveness.

Methods: An economic model was developed to estimate the incremental cost per quality-adjusted life year (QALY) gained from the perspective of the NHS in the UK. Health utilities were obtained from a survey of symptomatic hypothyroid patients. EQ-5D-5L profiles were converted to EQ-5D-5L index values (utilities, a preference-weighted measure of patients’ health evaluation) based on the UK EQ-5D-5L/3L cross walk value set. A survey of clinicians provided estimates of healthcare resource use/treatment efficacy.

Results: 37% of people responding to the survey reported severe problems in performing usual activities of everyday living. 22% reported severe anxiety/depression symptoms. Mean utility was 0.53 (the UK population norm for the EQ-5D-3L, for the age category of 45-54 years is 0.85) (SD 0.25), decreasing to 0.80 (0.26) for category 55-64 years. The mean (SD, minimum, maximum) EQ-VAS score was 49.3 (17.2, 5.0, 90.0)(100 indicates optimal health). The model indicated that at £11,881/QALY gained, the incremental cost effectiveness ratio fell below the cost-effectiveness threshold of £20,000/QALY operating in the NHS, and was stable to modelling assumptions. The probability of liothyronine/levothyroxine combination therapy being cost effective at this threshold was 0.56. The estimated value of eliminating the uncertainty surrounding the decision problem (£3.64m per year in UK) significantly exceeds the plausible costs of a clinical trial.

Conclusions: Liothyronine/levothyroxine combination therapy may represent a cost-effective treatment option for patients remaining symptomatic with levothyroxine alone. A definitive clinical trial is necessary to confirm clinical effectiveness, and would be justified given the value of the information gained far exceeds the cost.