Methods: We conducted telephone interviews from October 2004 to January 2006 on 2 populations in MA and PA: parents of children that had a false positive test result (n=73) and parents of children with normal test results (n=44). Preferences (values) for chronic conditions associated with metabolic disorders and for false positive test results were elicited using time trade-off (TTO) and willingness-to-pay (WTP) questions. Parents of children who had experienced a false positive test result (FP) were asked to value the false positive episode they experienced. Parents of children with normal test results (NT) were provided with a hypothetical description of a false positive test result. Differences between the 2 groups were evaluated using the Kolmogorov-Smirnov test.
Results: Parents of children with FPs were willing to trade 3.7 months (mean; 95% CI: 1.5, 6.9) to avoid a false positive test experience while parents of children with NTs were willing to trade 1.2 months (mean; 95%CI: 0.4, 2.8). Mean willingness to pay for the FP parent group was $159 (95% CI: 88, 237) and for the NT parent group was $544 (95% CI: 216, 1184). Median TTO and WTP amounts were zero for parents of children with FPs; parents of children with NTs had median values greater than zero (median TTO = 1 week; median WTP = $100). WTP values were significantly higher for parents of children with normal test results compared to parents of children that had experienced a false positive test result. Time trade-off amounts were not significantly different between the 2 groups.
Conclusions: Parents associate some reduction in quality of life with a false positive test result, but the magnitude and distribution of results suggests a high tolerance for false positives for many parents in our sample. Preferences for test outcomes associated with screening for metabolic disorders should be included in economic evaluations of expanded newborn screening programs.