Publication Errors

Harvey B-G, Strulovici-Barel V, Kaner RJ, Sanders A, Vincent TL, Mezey JG, Crystal RG. Risk of COPD with obstruction in active smokers with normal spirometry and reduced diffusion capacity. Eur Respir J 2015; 46: 1589-97.

This paper misleads the reader about the relationship between gas transfer (TLco) and risk of developing COPD in smokers.
The authors hid within an on-line supplement the way they chose the two groups of subjects for their study. One group had TLco above 80% predicted (see my section under 'Issues' on 'What is Abnormal?' as to why this is a misleading threshold). Their other group had TLco below a lower 95% confidence limit. They showed that this second group tended to develop COPD over time.

The misleading error was then to state that a TLco below 80% predicted was related to developing COPD. This ignores the fact that a very large number of subjects will have a TLco below 80% predicted but above their lower 95% confidence limit. The outcome of this large number of people was not investigated. This was a fatal flaw in their analysis and completely invalidates their conclusions.

Sadly this error was compounded by an Editorial about this paper from David Mannino and Barry Make (Eur Respir J 2015; 46: 1535-7) who did not spot this serious flaw in the paper.

In my opinion this paper should be withdrawn.