Context: Since the introduction of screening for congenital hypothyroidism (CH) in 1974, the optimal laboratory strategy has been the subject of debate.
Objective: To assess the clinical effectiveness and cost-effectiveness of various types of thyroxine (T(4))-based strategies to screen for CH.
Design, setting, and participants: In the Netherlands, since January 1, 1995, a primary T(4) determination with supplemental thyroid-stimulating hormone (TSH) and T(4)-binding globulin (TBG) measurements has been used. Results were calculated from cumulative findings for 1181079 children screened between January 1, 1995, and December 31, 2000.
Main outcome measures: Rates of detection of patients with CH of thyroidal origin (CH-T) or CH of central origin (CH-C), false-positive rates, laboratory costs, and costs of initial diagnostic evaluations.
Results: All known infants (n = 393) with CH-T and 92% (n = 66) of infants with CH-C were detected on the basis of low T(4) levels, TSH elevation, and/or low T(4)/TBG ratios. If the decision to refer had been based solely on TSH elevation, then 94% of patients with CH-T and none of the patients with CH-C would have been detected. If low T(4) levels (<or=-3.0 SD) and TSH elevation had been used as the criteria for referral, then the rates of detection would have been 96% for CH-T and 31% for CH-C. The false-positive rates for the 3 approaches were 0.5, 3.3, and 4.7 cases per case detected, respectively. The introduction of the T(4)/TBG ratio into a program using a primary T(4) with supplemental TSH approach generates an extra cost of 11206 dollars per additional case detected. The average costs to detect 1 patient are comparable for the 3 approaches. In addition, our data revealed a substantially greater prevalence of CH-C than reported previously (1 case per 16404 children, compared with earlier estimates of 1 case per 26000 infants to 1 case per 29000 infants).
Conclusions: The T(4) plus TSH plus TBG approach is a recommendable strategy for neonatal CH screening. It offers outstanding detection of patients with CH-C, in addition to those with CH-T, with acceptable costs.