Additional assessments ...
Bimodal scoring for CFQ (fatigue) makes recovery thresholds somewhat unreliable
The CFQ has 11 questions. There are 4 answers: "less than usual", "no more than usual", "more than usual", and "much more than usual" (different wording for the memory question ie better/worse rather than less/more).
Bimodal scoring means either "less/better than usual" and "no more/worse than usual" score 0, while either "more/worse than usual", and "much more/worse than usual" score 1. Hence the range is 0-11. Likert scoring means the answers are scored 0,1,2,3 respectively, hence the range of 0-33 with 11 as a neutral score.
PACE required >=6/11 for trial entry and apparently therefore <6/11 for recovery from Oxford criteria CFS. However, it is possible to be at 6/11 or so points at entry, get worse in several questions but better in one or two questions, then be classed as recovered from CFS!
Comparing the old with the new
"Recovery" will be defined by meeting all four of the following criteria: (i) a Chalder Fatigue Questionnaire score of 3 or less [27], (ii) SF-36 physical Function score of 85 or above [47,48], (iii) a CGI score of 1 [45], and (iv) the participant no longer meets Oxford criteria for CFS [2], CDC criteria for CFS [1] or the London criteria for ME [40].
All these were compulsory. This was abandoned. In the post-hoc definition of recovery, only the "normal range" (which overlaps with entry criteria for "disabling fatigue" and even allowed a participant to be worse) is compulsory.
The next (optional) criteria in the composite for recovery is no longer meeting Oxford criteria, which apparently (not absolutely clear) also includes scoring <=5 on the CFQ (bimodal scoring) for fatigue, and scoring >=70 in physical function. In other words, it is possible to be no longer meeting Oxford criteria because of these thresholds, not necessarily because the participant would not be arbitrarily diagnosed with Oxford criteria elsewhere if these thresholds were not bolted on. Furthermore, Oxford requires fatigue to be the only principle symptom, so if other symptoms get worse than fatigue, you cannot met Oxford criteria? Adding this on does almost nothing to the recovery rates despite presumably raising the threshold for good physical function by 10 points, which seems strange (unless they did not do this). Also note that scoring 4 or 5 in fatigue was regarded in the original protocol as "abnormal" or excessive fatigue.
The next (optional) criteria in the composite for recovery is a clinical global impression (CGI) score of 2 "much better" or 1 "very much better". Adding this on does reduce the recovery rates somewhat, suggesting that some of the previously recovered (according to the earlier criteria) did not feel much better or any better at all. CGI would appear to be the strictest criterion, even though in the original protocol it was even stricter ("very much better")?
Further requiring no longer meeting CDC criteria for CFS and/or no longer meeting London criteria v2 for ME does almost nothing to the recovery rates and seems superfluous now anyway, because Oxford is the broader definition, and those meeting CDC or London criteria but not Oxford at baseline were excluded. Also, they did not use the CDC criteria properly anyway in their definition for recovery (only required symptoms to be present or absent for 1 week instead of 6 months).
In the original protocol, there was also a "positive outcome" of either <=3/11 absolute score or 50% relative reduction in fatigue, or either >=75 absolute score or 50% relative increase in physical function. These were the weakest thresholds of improvement for fatigue and physical function in their original protocol, and chosen to be a significant difference from the entry criteria. PACE originally expected 60% of the CBT group to reach this threshold. It is ironic that the highest thresholds for these measures in their post-hoc definition for complete recovery are lower than their lowest thresholds for these measures in their original protocol. They were confident enough back in 2007 to use much stricter figures. This was abandoned and even FOI requests have failed to secure this data. What happened?
Why the composite criteria for recovery is not "conservative"
Using a spectrum of increasingly stricter composite criteria for recovery is fine, but their strictest criteria is not good enough and falls far short of the original protocol.
Although some would have improved more, it was possible to be completely "recovered" by improving one increment in physical function (5/100 points), and (apparently) improving one increment in fatigue score (1/11, even though it may have worsened overall, as per the above explanation under "Bimodal scoring for CFQ ..."), as long as you also scored feeling "much better" on the CGI scale. Their post-hoc threshold for recovered fatigue can be regarded as abnormal or excessive fatigue in the original protocol. Data on employment, welfare, walking distance test, etc, suggest no significant objective improvements. Coincidently this data was ignored. PACE was non-blinded with different levels of encouragement and optimism between groups, and the NNT of 7 is within range of a small placebo-response. APT was not best representative of pacing, and the SMC group contained elements of pacing.
The vast majority of healthy age-matched controls to middle-aged CFS patients would be scoring 90-100. PACE Trial participants were on average 39 years old at followup, and were ill for an average of 3 years at baseline. Almost all of them should be scoring 90-100 if recovered, not 60 or 70 or so. 70 means you have between, some limitations on most, or major limitations on three, of the ten questions asked about physical function.
Why aren't you naughty recalcitrants ditching pacing and celebrating the great White et al hope of CBT/GET?