I have been in touch with Dr Kathy Rowe, the sole author of the study, who was really helpful in providing additional information. Several points she mentioned are worth sharing (with permission): 1. To count as recovered, patients both had to say there were recovered and to specify how long their illness had lasted (answers given in reply to two separate questions). 2. Patients were also asked if they had had recurrence of symptoms. About 10% did, in the final stage before they recovered, almost always a symptom flare following an infection. Rowe reported that many recovering patients started to get infections more frequently as their health improved (this phenomenon has also been reported elsewhere). However, in almost all cases the recurrence of symptoms was only temporary (i.e. this is recovery not remission). 3. Rowe also said that some patients' classification of themselves as recovered partly depended on their approach to life, particularly among those who scored 8 or 9/10. The paper itself said similar. Rowe also said that this didn't apply to those scoring 10/10, who were all mailed on. And that most of those who scored less than 8 would doing so for reasons they regarded as unrelated to ME/CFS, particularly anxiety or depression. My interpretation of the final points is that the true rate of recovery would be below the headline figure. I'd suggested in my earlier post that the long term rates (10 year + follow-up) might be perhaps 50% or so, rather than the 68% figure. That is an interpretation, but, particularly after the discussion I had with Dr Rowe, I think this large study of the very high follow-up rate still demonstrates a very substantial recovery rate.