RESUMO
BACKGROUND: The systematic aggregation of research on cognitive behavioral therapy (CBT) in chronic fatigue syndrome (CFS) needs an update. Although meta-analyses evaluating interventions typically focus on symptom reduction, they should also consider indicators of treatment acceptability, e.g., drop-out rates. METHODS: Randomized controlled trials (RCTs) investigating CBT in adults with CFS compared to inactive and non-specific control groups were included. First, efficacy was examined, considering fatigue, depression, anxiety, and perceived health. Secondly, drop-out rates through different trial stages were analyzed: Non-completion of all mandatory sessions, drop-out (primary study definition), treatment refusal (non-starters), and average of sessions completed. RESULT: We included 15 RCTs with 2015 participants. CBT was more effective than controls in fatigue (g = -0.52, 95%CI -0.69 to -0.35), perceived health, depression, and anxiety at post-treatment. At long-term follow-up the effects were maintained for fatigue and anxiety. Rates of non-completion (22%, 95%CI 3-71), drop-out (15%, 95%CI 9-25), and treatment refusal (7%, 95%CI 3-15) were relatively low, with a high average proportion of sessions completed. Total time of therapy moderated the effect on fatigue, while the number of sessions moderated the effect on perceived health. Fatigue severity influenced adherence. CONCLUSION: The results indicate that CBT for CFS is effective in reducing fatigue, fatigue related impairment, and severity of depression and anxiety. Conclusions on efficacy at follow-ups are still limited. However, adherence is high in CBT. The results may help to inform clinical practice. Future research should focus on examining the maintenance of effects, while also emphasizing the importance of treatment acceptance.