Just to be clear, here are at least two factual errors published in the recovery paper:
We changed our original protocol’s threshold score for being within a normal range on this measure from a score of >=85 to a lower score as that threshold would mean that approximately half the general working age population would fall outside the normal range. The mean (S.D.) scores for a demographically representative English adult population were 86.3 (22.5) for males and 81.8 (25.7) for females (Bowling et al. 1999). We derived a mean (S.D.) score of 84 (24) for the whole sample, giving a normal range of 60 or above for physical function.
FAIL. In the general working age population, the median (middle score) is 100 and the 1st quartile (25th percentile) is 90. A threshold of >=85 only excludes about 18% of the general working age population, and 8% of the working age population without long-term health problems, the population which 'recovered' participants should be compared to. White et al appeared to wrongly assume that the mean (average score) was about the same as the median.
So the stated justification for changing the threshold is based on a falsehood and/or misinterpretation. Unfortunately, those figures are derived from raw data from the
UK Data Archive and not published in a paper (however, one can estimate from the histogram in the Bowling paper that about 28% of the general population score 85 or higher). Psychological Medicine were made aware of this error but did not publish the submitted letter with this information, claiming that the same point was already made in one of the other letters to be published, which is clearly false. There was no correction issued either. Another letter made a different point about the threshold, but here is a factual error which they are obliged to investigate and correct.
How do these results compare with previous studies? We are not aware of any previous studies that have compared comprehensively defined recovery between different treatments. Two studies of recovery in adults after CBT found similar proportions in recovery: 23% and 24% (Deale et al. 2001; Knoop et al. 2007), compared with 22% in the PACE trial. [...] The other study used similar criteria and domains for recovery (Knoop et al. 2007), but the definition for normal range used was the more liberal population mean -2S.D. rather than the more conservative 1 S.D. that we used; the treatment was delivered by therapists in one specialist CFS centre and outside of a trial setting.
FAIL. The PACE Trial recovery thresholds were not 'more conservative' than the Knoop et al paper. Both used mean -1S.D. The threshold for normal physical function was 80 in Knoop et al but only 60 in the PACE Trial. White was a co-author of both papers, which makes the blunder more baffling. Fortunately, the above error is very easy to confirm. I don't know if Psychological Medicine know of this error, but they don't seem interested in corrections anyway.
PS: PACE referred to Bowling et al for their normative data (general population), which was based on the 1992 ONS Omnibus Survey sample. The mean±S.D. and median(IQR) physical function score for the working age population without chronic illness in this sample is 95.0±10.2 and 100(95-100) points respectively. Presenting 60 as a 'conservative' threshold for complete recovery is scandalous, particularly as it overlapped with trial criteria for 'significant disability' i.e. 65 or less.