Systematic review of the current literature related to disability and chronic fatigue syndrome.

s demonstrating any of the following characteristics will be rejected: • Review, meta-analysis, abstracts, letters, case reports, editorials, and commentaries. • Unpublished study reports and abstracts. • Studies published prior to 1988. • Studies written in languages other than English. • Studies not conducted in the US, Canada, Australia or Western Europe. • Pharmacokinetic and pharmacodynamic studies. • Animal or in vitro or tissue level studies. • Studies not related to or not specific to CFS disability or impairment. • Studies containing < 2 patients as total sample size. • Pediatric patient population. • No information related to disability or impairment. • Outcomes not extractable. • Mixed population (unable to separate CFS from other populations). • Studies focused on pathophysiology of CFS (lab findings/lab technique). In some cases, it may not be possible from the abstract alone to determine the eligibility of the study. Full studies of abstracts lacking obvious exclusion criteria will be retrieved for Level 2 screening, where inclusion and exclusion criteria will be applied.