Discussion
MS-related fatigue, fatigue, Fatigue
SECONDARY, DISEASES, CHRONIC DISEASE
The aim of this study was to determine whether a blended booster programme could prevent fatigue relapse and improve long term effects of CBT for MS-related fatigue. No significant effect of the booster programme was found on fatigue severity and secondary outcomes at 1-year follow-up. Since fatigue severity did not increase in both conditions during the follow-up period, this study also indicates that wearing off of the positive effect of CBT on fatigue did not occur. No differences between booster- and control condition were found on secondary outcomes as well.The absence of the expected effect of the booster programme, compared with the no booster control condition, is most likely explained by the fact that the control group did not show a relapse in fatigue severity. This latter finding was surprising, considering the relapse after successful treatment found in the TREFAMS-CBT study, using the same treatment protocol and inclusion criteria.However, when comparing the results with other RCTs on CBT for MS-related fatigue, there is no indication that treatment duration predicts long-term effects. Most studies had a treatment duration between 8 and 12 weeks, and also reported sustained treatment effects, although not all studies assessed patients up till 1 year.In the present study, therapists and patients knew that CBT was an effective treatment, but that relapses might occur. Mediation analysis had shown which factors mediated the effect of CBT and which factors mediated relapse in fatigue severity after 1 year.At the time of the TREFAMS-CBT study (2010–2017), CBT for MS-related fatigue was not implemented in the Netherlands yet, and only a few international studies had shown positive outcomes of CBT for fatigue in MS. Fatigue was considered as a chronic symptom which was difficult to influence and treatment as usual was mostly aimed at coping with fatigue instead of reducing fatigue. During the present study, CBT was more solidly evidence-based, which may have affected the attitude and expectancies of therapists and patients in a positive way.Maintaining treatment effects of fatigue interventions in chronic progressive diseases may be especially challenging, considering the fact that patients will be faced with ‘everyday’ fatigue, which in the context of the chronic disease may be perceived as a disease-specific symptom. This may increase the risk of dysfunctional coping strategies in response to fatigue and thereby increase the risk of perpetuating fatigue. Although the present study showed promising results in sustaining treatment effects, the follow-up period of 1 year after start of treatment is relatively short. No studies have reported treatment effects of CBT on fatigue severity in MS patients on a longer term than 1 year. So the longer-term course of fatigue and the effects of boosters are not known. It would be of clinical relevance to study the outcome of CBT over a longer follow-up period, and to get a better understanding of factors mediating the long-term effects of CBT for fatigue. Booster sessions could potentially be beneficial for patients at high risk for relapse in fatigue severity or dysfunctional behaviour patterns.