Not using age specific values invalidates study

BMJ 1995;311:1371 (18 November)

Letters

Not using age specific values invalidates study

EDITOR,--J Fletcher and colleagues' paper does little to helppurchasing authorities when they have to decide which screeningprogramme and screening policy to choose when introducing screeningfor Down's syndrome.¹ While the methodology used in the paperis valuable when used correctly, the authors were wrong to applythe overall sensitivity and specificity of serum testing obtainedfrom whole population data rather than using age specific values.They argue that "this was done to reduce complexity." As a consequenceof their not making allowance for the fact that in older women(those over 30) the sensitivity and specificity change dramaticallywith age, the results of their analysis are invalidated.

Making allowance for the changing sensitivity and specificitywith age is quite simple, and several authors have publishedboth theoretical and actual detection rates and false positiverates by broad age bands.² ³ ⁴ The table gives the results forFletcher and colleagues' . . . [Full text of this article]

Add to CiteULike CiteULike Add to Complore Complore Add to Connotea Connotea Add to Del.icio.us Del.icio.us Add to Digg Digg Add to Reddit Reddit Add to StumbleUpon StumbleUpon Add to Technorati Technorati What's this?

Relevant Article

Using decision analysis to compare policies for antenatal screening for Down's syndrome: J Fletcher, N R Hicks, J D S Kay, and P A Boyd
BMJ 1995 311: 351-356. [Abstract] [Full Text]