Thesis defense Margreet Worm-Smeitink (Donders series 545)

22 April 2022

Promotors: prof. dr. M.J.P. Wensing, prof. dr. J.A. Knoop

Cognitive behavior therapy. Learning from variations.

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a condition characterized by severe fatigue and functional impairments. Cognitive behaviour therapy (CBT) can effectively reduce fatigue and impairment. Unfortunately, not all patients profit. This thesis explores how to increase efficacy. We found treatment efficacy depended on the treatment protocol used. Furthermore, we found there were personal differences in how fatigue is maintained. These did not seem to influence treatment efficacy. It did therefore not yet lead to insight into how treatment can be personalized, to increase efficacy. We found a less intensive format of CBT, webbased CBT (I-CBT), was sufficiently effective for a subgroup of patients. If patients who are still severely fatigued or disabled after I-CBT receive additional face-to-face (f2f) CBT, a subgroup is no longer severely fatigued or disabled. patients profited. This format of stepped care was as effective as f2f CBT alone, but required considerably less therapist time to deliver. When implemented in mental health care centres, stepped care was relatively less effective. Further research should indicate how CBT for CFS can optimally be offered in routine care, in order to increase access to this effective treatment.