BACKGROUND: Effective treatment of chronic fatigue syndrome (CFS) with cognitive behavioural therapy (CBT) relies on a correct classification of so called 'fluctuating active' versus 'passive' patients. For successful treatment with CBT is it especially important to recognise the passive patients and give them a tailored treatment protocol. In the present study it was evaluated whether CFS patient's physical activity pattern can be assessed most accurately with the 'Activity Pattern Interview' (API), the International Physical Activity Questionnaire (IPAQ) or the CFS-Activity Questionnaire (CFS-AQ). METHODS: The three instruments were validated compared to actometers. Actometers are until now the best and most objective instrument to measure physical activity, but they are too expensive and time consuming for most clinical practice settings. In total 226 CFS patients enrolled for CBT therapy answered the API at intake and filled in the two questionnaires. Directly after intake they wore the actometer for two weeks. Based on receiver operating characteristic (ROC) curves the validity of the three methods were assessed and compared. RESULTS: Both the API and the two questionnaires had an acceptable validity (0.64 to 0.71). None of the three instruments was significantly better than the others. The proportion of false predictions was rather high for all three instrument. The IPAQ had the highest proportion of correct passive predictions (sensitivity 70.1%). CONCLUSION: The validity of all three instruments appeared to be fair, and all showed rather high proportions of false classifications. Hence in fact none of the tested instruments could really be called satisfactory. Because the IPAQ showed to be the best in correctly predicting 'passive' CFS patients, which is most essentially related to treatment results, it was concluded that the IPAQ is the preferable alternative for an actometer when treating CFS patients in clinical practice.

Health Qual Life Outcomes. 2009 Apr 1;7:29. Scheeres K, Knoop H, Meer J, Bleijenberg G. Expert Centre Chronic Fatigue, Radboud University Nijmegen Medical Centre (4628), PO Box 9101, 6500 HB Nijmegen, The Netherlands. korinescheeres@gmail.com

Dave graduated in 1978 as an engineering technologist. He later worked in the Faculty of Dentistry at the University of Alberta designing TMJ Dysfunction related diagnostic equipment and research facilities. He organized research projects, taught basic physiology and the advanced TMJ diagnostics course. Dave had noted anxiety issues in many patients suffering with TMJ dysfunction, prompting him to study biofeedback, which he applied to their patients and later design biofeedback devices. In 1984, Dave designed his first audio-visual entrainment (AVE) device – the "Digital Audio-visual Integration Device," or DAVID1. Since this time, through his company, Mind Alive Inc., Dave has been researching and refining AVE technology since, specifically for use in relaxation, and treating anxiety, depression, PMS, ADD, FMS, SAD, pain, cognitive decline and insomnia, which he presents at conferences and for special interest groups. Dave also designs Cranio-Electro Stimulation (CES), transcranial DC stimulation and biofeedback devices. Dave continues to conduct research and designs new products relating to personal growth and wellness.

For more information visit www.MindAlive.com.