Trends in Iodine Deficiency Disorders from 1980 to 2010

Abstract

"<bold>Background:</bold>" Iodine is an essential mineral for normal thyroid function and its deficiency is estimated to affect 2 billion people worldwide. The assessment of iodine deficiency has seen measurable changes over time, shifting from goiter prevalence to urinary iodine deficiency in the early 2000s. This presents challenges to estimating iodine deficiency trends over time because data on UIC pre-2003 is limited and few studies have analyzed the relationship between UIC and goiter prevalence. Our study maximizes existing data sources on UIC and goiter using novel modeling techniques to describe trends in goiter and cretinism prevalence, and household iodized salt consumption. "<bold>Methods:</bold>" We used the WHO VMNIS database on goiter and UIC, and the UNICEF databases on consumption of household iodized salt to model trends of prevalence from 1980 to 2010. We estimated the relationship between UIC and goiter prevalence, and modeled goiter in DisMod 3, a Bayseian meta-regression tool used for modeling multiple disease outcomes. We also modeled cretinism in DisMod 3, and estimated trends in household iodized salt consumption using a spatio-temporal regression model. "<bold>Results:</bold>" We estimated a total of 180 million people with goiter in 2010, up from 139 million in 1990, indicating that global goiter prevalence has seen relatively little change over time, remaining at a global prevalence of 7.15%. We found modest reductions in prevalence by region, with decreases in Sub-Saharan Africa from 14.6% to 14.2% and South Asia from 10.1% to 8.8%. In contrast, the global trend of iodized salt consumption has made significant progress, particularly in China, where consumption rose from 73% to 97%, and Brazil, where consumption rose from 77% to 96% . Likewise, the global prevalence of cretinism has declined from 22 per 100,000 in 1990 to 3 per 100,000 in 2010, representing an annual rate of decline of 8.8%. "<bold>Conclusions:</bold>" Our findings show that significant progress has been made in the consumption of adequately iodized salt, aiding remarkable declines in cretinism prevalence. At the global level, goiter prevalence has remained stagnant, but measurable declines were found in countries with expanded iodized salt programs , such as India. These findings underscores the importance of implementing regulatory frameworks to monitor production and distribution of salt, to ensure that a population has access to high quality iodized salt.