Figure 1

Decision tree: Expansion of newborn screening to include MCADD vs. current newborn screening. The square represents a decision node, circles chance nodes, and triangles terminal nodes. The branch of the decision node “MCADD screening” is compared to “No MCADD screening” which is the current situation. Probabilities, costs, and QALY are calculated at each terminal node according to the parameters described in Table 1. To evaluate the concurrent cost-effectiveness of switching to MS/MS for PKU screening, the cost of the current technology to screen for PKU was subtracted from the cost of the MCADD screening test as described in the text.