Key result
Screening 1 million children for Long QT syndrome using a QTc cut-off of 0.50 seconds would identify only 61 of 200 affected cases, at an estimated cost of $2,222,000 per death avoided.
Why the study?
Do rate corrected QT interval and DNA analysis serve as effective screening tests for long QT syndrome in the general pediatric population?
Observational (n=250)
Do rate corrected QT interval and DNA analysis serve as effective screening tests for long QT syndrome in the general pediatric population?
Screening for long QT syndrome in the general pediatric population using ECG or DNA analysis is currently limited by low sensitivity and high costs.
May inform QTc thresholds for pediatric LQTS screening in genotyped families; leaves open prospective validation before clinical use.
OBJECTIVE: To evaluate two hypothetical screening strategies for identifying children with long QT syndrome (LQTS), a cause of sudden death in childhood. METHODS: Families with KVLQT1, HERG, or SCN5A genotypes provided electrocardiographic (ECG) data for this analysis. This is the first time such genotype-phenotype information has been available. Using the LQTS genotype, the distributions of QTc in affected and unaffected children were established and screening performance for various QTc cut off points were modelled. The detection rate for DNA mutation analysis was determined from published experience. RESULTS: The mean QTc (SD) was 0.484 seconds (0.031) in 117 affected children and 0.420 seconds (0.021) in 133 unaffected children. A QTc cut off of 0.50 seconds in a population of 1 million children would identify 61 of the 200 affected children, and 100 unaffected children. Estimates of testing costs for a screening programme in the newborn period would be $327 869/case detected and $2 222 000/death avoided. Although not presently available for routine use, DNA analysis could, theoretically, identify 100 of the 200 children with LQTS within the same population, along with an estimated 100 unaffected children. CONCLUSION: The only available screening test for LQTS is ECG measurement. If DNA technology becomes available for screening, unit costs must be very low to be competitive. There are multiple problems with screening for LQTS: only a minority of children will be detected, cost/death avoided is high, and pilot studies would need to be in place for 5-10 years to document efficacy.
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Allan et al. (2001) conducted an observational in Long QT syndrome (LQTS) (n=250). ECG measurement and DNA analysis was evaluated on Screening performance and detection rate. Screening 1 million children for Long QT syndrome using a QTc cut-off of 0.50 seconds would identify only 61 of 200 affected cases, at an estimated cost of $2,222,000 per death avoided.
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