Predictors of intellectual outcome in a cohort of Brazilian children with congenital hypothyroidism

OBJECTIVE To identify predictors of intellectual development in a cohort of children with permanent primary congenital hypothyroidism. DESIGN Cohort study with intellectual development as the outcome. PATIENTS AND MEASUREMENTS Thirty-one consecutive newborns with permanent primary congenital hypothyroidism diagnosed by a screening programme were recruited from the outpatient clinic of a district hospital and underwent psychometric evaluation with the Wechsler Intelligence Scales after a minimum follow-up of 4 years. RESULTS Eight of the 31 patients (25.8%) presented impaired intellectual development (full-scale intellectual quotient < 85), and one of them presented mental deficiency (full-scale intellectual quotient less than or equal to 69). The following were associated with worse prognosis: initial serum T4 levels less than or equal to 32.18 nmol/l, treatment beginning after 30 days of age, fewer than seven clinic visits during the first year of life, living in rural areas, nonintellectual parental occupation and little parental schooling. In a multiple regression analysis, only maternal schooling (B = 0.401; beta coefficient = 13.053, P = 0.063), number of clinic visits during the first year of life (B = 0.382; beta coefficient = 4.145, P = 0.047) and initial serum T4 (B = 0.287; beta coefficient = 1.336, P = 0.089) remained significantly associated with full-scale intelligence quotient scores. CONCLUSION Maternal schooling, number of visits during the first year of life and baseline T4 levels were the main predictors of cognitive outcome in this cohort of patients.