Risk factors of congenital hypothyroidism using propensity score: a matched case-control study.

BACKGROUND The aim of this study was to investigate the relationship between congenital hypothyroidism and several variables using two different adjustment methods. METHODS This matched case-control study was conducted in Hamadan Province, the west of Iran, in 2012 enrolling neonates born between 2005 and 2011 and covered by screening program for congenital hypothyroidism. The neonates with TSH titer more than 10 mU/l or T4 titer less than 6.4 μg/dl were considered as cases. Each case was individually matched for birth place and year with four neonates with normal TSH and T4 titers as controls. The data were analyzed using two different approaches including propensity score and multiple conditional logistic regression model. RESULTS Of 1313 enrolled neonates, 277 (159 girls) were cases and 1036 (531 girls) were controls. The most important prognostic factors which had significant effect on congenital hypothyroidism included twin, birth season, maturity, jaundice at birth, birth weight, age at pregnancy, maternal anemia and goiter, gestational age, delivery type, father's education and smoking status, and consanguinity. The associations reported by logistic regression were stronger that of than propensity score analysis in most items, although the differences were not statistically significant. CONCLUSIONS We addressed the effect of numerous potential risk factors on congenital hypothyroiditis and the impact of these factors on the disease occurrence. However, future prospective studies are needed to test these findings and hypothesis and to investigate the true effect of these potential risk factors on congenital hypothyroiditis.