Benefits and Harms of a Prevention Program for Iodine Deficiency Disorders: Predictions of the Decision-Analytic EUthyroid Model.

Background: Iodine deficiency is one of the most prevalent causes of intellectual disability and can lead to impaired thyroid function and other iodine deficiency disorders (IDDs). Despite progress made on eradicating iodine deficiency in the last decades in Europe, IDDs are still prevalent. Currently, evidence-based information on the benefit/harm balance of IDD prevention in Europe is lacking. We developed a decision-analytic model and conducted a public health decision analysis for the long-term net benefit of a mandatory IDD prevention program for the German population with moderate iodine deficiency, as a case example for a European country. Methods: We developed a decision-analytic Markov model simulating the incidence and consequences of IDDs in the absence or presence of a mandatory IDD prevention program (iodine fortification of salt) in an open population with current demographic characteristics in Germany and with moderate ID. We collected data on the prevalence, incidence, mortality, and quality of life from European studies for all health states of the model. Our primary net-benefit outcome was quality-adjusted life years (QALYs) predicted over a period of 120 years. In addition, we calculated incremental life years and disease events over time. We performed a systematic and comprehensive uncertainty assessment using multiple deterministic one-way sensitivity analyses. Results: In the base-case analysis, the IDD prevention program is more beneficial than no prevention, both in terms of QALYs and life years. Health gains predicted for the open cohort over a time horizon of 120 years for the German population (82.2 million inhabitants) were 33 million QALYs and 5 million life years. Nevertheless, prevention is not beneficial for all individuals since it causes additional hyperthyroidism (2.7 million additional cases). Results for QALY gains were stable in sensitivity analyses. Conclusions: IDD prevention via mandatory iodine fortification of salt increases quality-adjusted life expectancy in a European population with moderate ID, and is therefore beneficial on a population level. However, further ethical aspects should be considered before implementing a mandatory IDD prevention program. Costs for IDD prevention and treatment should be determined to evaluate the cost effectiveness of IDD prevention.