Concordance of mMRC and CAT when used for COPD classification according to GOLD 2011 Norbert Banik, Winicker Norimed Medical Research GmbH, Munich, Germany 16 July 2013 I read your article with big interest. It seems that we now have already a couple of indications that the two alternative classification systems suggeted by GOLD will need some revision - as you also concluded. I wanted to make you aware of a similar work which appeared online in ERJ already in December 2012 (http://erj.ersjournals.com/content/early/2012/12/19/09031936.00125612.abstract). Unfortunately it did not show up in print yet. I want to mention that CAT is a validated score and item-wise use is not intended. The correlation analyses you presented with regard to single CAT items and mMRC is thus lacking a methodological sound basis. Competing interests No conflicting interests.