Limited evidence was found for the psychometric properties and clinical usability of these instruments .
However , the CFS-activities and participation question naire ( APQ ) is a disease-specific instrument with moderate content and construct validity .
PURPOSE To summarize measurement instruments used to evaluate activity limitations and participation restrictions in patients with chronic fatigue syndrome ( CFS ) and review the psychometric properties of these instruments .
Chronic fatigue syndrome causes activity limitations and participation restrictions in one or more areas of life .
Measuring disability in patients with chronic fatigue syndrome: reliability and validity of the Work and Social Adjustment Scale.
BACKGROUND Disability is a defining feature of chronic conditions , and it is an increasingly used measure of therapy effectiveness . The  Work and Social Adjustment Scale ( WSAS )  is a simple and clear measure of disability . Although the scale is widely used , no study has yet investigated its psychometric properties in patients with chronic fatigue syndrome ( CFS ) . METHODS Data from two sample s of patients were used , one from a multicenter r and omized controlled clinical trial of treatments for CFS ( n = 639 ) and the other from a clinic that specializes in CFS ( n=384 ) . All patients completed the WSAS as well as other measures . RESULTS Internal consistency and the Spearman-Brown split-half coefficient values indicated that the scale is reliable . CFS patients who had comorbid diagnoses of depression , anxiety or fibromyalgia had higher WSAS scores . High levels of disability were associated with high number of physical symptoms , severe fatigue , depression , anxiety , poor sleep quality and poor physical fitness , with correlation coefficients ranging between 0.41 and 0.11 . Lower scores on the WSAS were modestly associated with better physical functioning as well as higher levels of physical capacity as assessed by a walking test . Sensitivity to change was evaluated in a subgroup of patients who had undergone a course of cognitive behavioral therapy .  Disability significantly decreased after therapy and remained stable at follow-ups . CONCLUSION The WSAS is a reliable and valid assessment tool for disability in patients with CFS
Limited evidence was found for the psychometric properties and clinical usability of these instruments .
However , the CFS-activities and participation question naire ( APQ ) is a disease-specific instrument with moderate content and construct validity .
PURPOSE To summarize measurement instruments used to evaluate activity limitations and participation restrictions in patients with chronic fatigue syndrome ( CFS ) and review the psychometric properties of these instruments .
Chronic fatigue syndrome causes activity limitations and participation restrictions in one or more areas of life .