Recovery from chronic fatigue syndrome: a systematic review-heterogeneity of definition limits study comparison.

Definitions of recovery are highly variable, likely secondary to differences in study design, outcomes used, follow-up and study populations. Heterogeneous definitions of recovery limit meaningful comparison between studies, highlighting the need for a consensus definition going forward. Recovery is probably best defined from the child's own perspective with a single self-reported measure. If composite measures are used for research, there should be agreement on the core outcome set used.