Cost-effectiveness analysis of universal hypothyroidism screening in the general population aged 30–65 years in Spain

Abstract

Aims Hypothyroidism is an endocrine disorder that often begins in a subclinical form but can lead to non-specific symptoms and cardiovascular problems. Its prevalence is higher among women, and a significant proportion of cases remain undiagnosed. While previous studies assessed screening in specific populations (e.g. pregnant women, older adults), this study evaluates the cost-effectiveness of population-wide screening in adults aged 30–65 from the Spanish National Health System (NHS) perspective. Materials and methods A cost-effectiveness Markov model was developed, simulating seven health states: subclinical hypothyroidism (undiagnosed and controlled), overt hypothyroidism (undiagnosed and controlled), euthyroid state, cardiovascular event, and death. Two strategies were compared: population-based screening versus no screening. Model inputs-transition probabilities, prevalence, costs, utilities, and screening effectiveness-were obtained from published literature. A panel of four clinical experts validated the model structure and assumptions. Lifetime costs and quality-adjusted life-years (QALYs) were estimated, and the incremental cost-effectiveness ratio (ICER) was calculated. Probabilistic, sensitivity, and scenario analyses were conducted. Results Population-based screening for hypothyroidism in individuals aged 30–65 resulted in an incremental cost of €34.7 million and 6,037 QALYs gained over 35 years, yielding an ICER of €5,745/QALY, significantly below the Spanish willingness-to-pay threshold (€21,000/QALY). Screening also resulted in 33,215 additional diagnoses of subclinical hypothyroidism and 6,870 fewer cases of overt hypothyroidism. It was cost-effective in 99% of probabilistic simulations and under all tested screening intervals (1–5 years). Limitations and conclusions Key limitations include the use of constant transition probabilities and some inputs from international sources. Nonetheless, expert validation supports the model’s relevance. The analysis adopts a conservative approach, excluding potential additional benefits like hyperthyroidism detection or integration with routine bloodwork, which could improve cost-effectiveness. Overall, hypothyroidism screening is a cost-effective strategy for the Spanish NHS, improving early detection, preventing progression, and enhancing quality of life in a frequently underdiagnosed population.