Erratum

CORRECTION TO ARTICLE PUBLISHED IN JUNE 2007

It has been brought to our attention that there are two errors in our paper on setting truncation limits for marker values in medical screening (J Med Screen 2007;14:103–106). ¹

In the footnote to Table 1, the early mid-trimester age-specific risk of a Down's syndrome pregnancy for a 30-year-old woman was given as 1:1250. This should have been 1:720. Due to this the risk figures in the table are incorrect. The corrected Table 1 is reproduced here.

The second error was in the formula on page 104 used to calculate the point of risk reversal. The subscript A should be a U, as given in the text. The formula is corrected below:

Table 1

The observed and truncated risk for a 30-year-old woman according to the value of nuchal translucency (NT)

Observed likelihood			Truncated likelihood
NT value	Ratio	Risk	NT value	Ratio	Risk
3.0	125	1 in 7	2.5	28	1 in 27
0.5	0.12	1 in 6000	0.65	0.11	1 in 6550

The age-specific risk for a 30-year-old woman is about 1:720. The truncation limits for NT are 0.65–2.5 MoM

Neither error affects the conclusions in the paper.