Orthostatic symptoms predict functional capacity in chronic fatigue syndrome: implications for management.

OBJECTIVES To establish the relationship between the functional impairment experienced by Chronic fatigue syndrome (CFS) patients and the symptoms frequently experienced by those with CFS; specifically cognitive impairment, fatigue and orthostatic symptoms. DESIGN Cross sectional questionnaire survey. SETTING Specialist CFS Clinical Service. SUBJECTS Ninety-nine Fukuda diagnosed CFS and 64-matched controls. MAIN OUTCOME MEASURES Symptom and functional assessment tools completed and returned by post included; PROMIS HAQ (Patient-Reported Outcomes Measurement Information System, Health Assessment Questionnaire), CFQ (Cognitive Failures Questionnaire), FIS (Fatigue Impact Scale) and OGS (Orthostatic Grading Scale) assessment tools. RESULTS CFS patients experience greater functional impairment than controls [mean (95% CI) PROMIS HAQ scores CFS 36 (31-42) vs. controls 6 (2-10); P < 0.0001], especially in the functional domains of activities and reach. Poorer functional ability impairment is significantly associated with greater cognitive impairment (P = 0.0002, r = 0.4), fatigue (P < 0.0001, r = 0.5) and orthostatic symptoms (P < 0.0001, r = 0.6). However, only orthostatic symptoms (OGS) independently associated with functional impairment (beta = 0.4, P = 0.01). CONCLUSION Treatment of orthostatic symptoms in CFS has the potential to improve functional capacity and so improve quality of life.