Epidemiology of hyperthyroidism in Iran: a systematic review and meta-analysis

Hyperthyroidism is a systemic disorder that causes severe morbidity and is even fatal. Several studies have been performed in Iran to determine the epidemiologic properties of hyperthyroidism; however, they did not use a systematic approach or meta-analysis to evaluate the results. Therefore, this systematic review and meta-analysis aimed to evaluate the epidemiologic data on hyperthyroidism in Iran.

In order to find all relevant papers published by October 2017, we searched both international (Web of Science, Scopus, PubMed, Embase, and Cochrane library) and Persian databases (Scientific Information Database, Magiran, and Barekat Knowledge Network System). Meta-analysis was performed using metaprop random effects analysis for prevalence and metaprop fix effect analysis for incidence by Stata statistical software. I² was used for the demonstration of heterogeneity.

Of 7667 published papers or conference proceeding, 7448 studies were removed after eliminating duplicates and reviewing titles/abstracts. Finally, after reviewing 219 full texts, 18 papers met the inclusion and exclusion criteria. The pooled prevalence of total, overt, and subclinical hyperthyroidism in general population were 2.43% (95% CI: 0.23-4.63%), 0.69% (95% CI: 0.21-1.18%), and 1.52% (95% CI: 0.14-2.89%), respectively. The pooled annual incidence of total hyperthyroidism was 2.2 (95% CI: 1.1-3.3) per 1000 population: 0.8 (0.1-1.4) and 1.3 (0.4-2.2) per 1000 population for overt and subclinical hyperthyroidism, respectively.

This is the first systematic review and meta-analysis, which investigated the epidemiology of hyperthyroidism in Iran. It seems that the prevalence and incidence of hyperthyroidism among the general population in Iran is similar to that in other parts of the world.