[5][6] Notable authors include psychiatrists Michael Sharpe and Peter White, along with psychotherapist Trudie Chalder.
[5][1] SMC consisted of specialists giving advice to patients, such as “to avoid extremes of activity and rest”, and the prescription of drugs to help manage symptoms.
Additionally the subjects received a substantial amount of therapy (GET or CBT), over an extended duration, which contributed increased precision in the findings.
A patient was considered recovered if they obtained a specified threshold score on the fatigue and physical function self-report scales, if they rated their health as "much better" or "very much better", and if they also failed to meet the authors' case definition of CFS.
[5] A follow-up conducted 2.5 years after the commencement of the trial reported no significant differences between the various treatment groups on the primary self-report measures.
[13][14][15][16][17] Lancet Editor Richard Horton defended the trial, calling the critics "a fairly small, but highly organized, very vocal and very damaging group of individuals who have, I would say, actually hijacked this agenda and distorted the debate so that it actually harms the overwhelming majority of patients.
Ronald Davis of Stanford University wrote, "I'm shocked that the Lancet published it […] The PACE study has so many flaws and there are so many questions you'd want to ask about it that I don't understand how it got through any kind of peer review".
[2] There has been considerable criticism due to the original findings only being supported by subjective (participant reported) primary outcome measures.
"[26] The authors responded that a number of objective measures were taken, and the GET group had significant improvement in the 6 minute walking time.
The authors said they chose patient-reported primary outcomes as they thought patients themselves were the best people to judge the state of their own health.
[23] The patient newsletter given throughout the study subtly praised CBT, GET, and “activity management” by saying a government committee had approved them as treatments, while critiquing biomedical research in ME/CFS.
[28] David Tuller of University of California, Berkeley replied that trial participants would not necessarily be aware that the authors considered “adaptive pacing therapy” as a subtype of “activity management”.
[29] Multiple authors of the PACE trial noted potential conflicts of interest in their scientific publications, having worked for or received royalties from disability insurance companies who would benefit from there being a treatment for ME/CFS.
42 scientists criticised this in an open letter saying it meant there was a lack of informed consent and breached the Helsinki Protocol.
[30] However, the request was initially denied and several of the researchers involved in the PACE trial, reported to the press that they had been verbally abused by patients.
[34] The argument that ME/CFS patients and their organisations were militant and using methods of harassment was used by the authors to argue against a release of the trial's data.
[2] The UK Health Research Authority began an inquiry into the PACE trial in 2018, in response to questions from MP Carol Monaghan.
[4][42] As of 2024, the Cochrane guidelines conclude that GET likely reduces fatigue for those diagnosed under older criteria sets, partially based on evidence from the PACE trial.