Clinical assessment of the physical activity pattern of chronic fatigue syndrome patients: A validation of three methods – Source: Health and Quality of Life Outcomes, Apr 1, 2009

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Effective treatment of chronic fatigue syndrome (CFS) with cognitive behavioral therapy (CBT) relies on a correct classification of:

• So called ‘fluctuating active’ [generally, “infrequent bursts of activity followed by extreme exhaustion” – some 75% of patients]

• Versus ‘passive’ patients [“who usually avoid activities as much as possible”].

For successful treatment with CBT, it is especially important to recognize 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 [interview questions/questionnaires] 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 instruments. The IPAQ had the highest proportion of correct passive predictions (sensitivity 70.1%).

Conclusions: The validity of all three instruments appeared to be fair, and all showed rather high proportions of false predictions.

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 [to] an actometer when treating CFS patients in clinical practice.

Source: Health and Quality of Life Outcomes, Apr 1, 2009. 7(29). DOI:10.1186/1477-7525-7-29, by Scheeres K, Knoop H, van der Meer J, Bleijenberg G. Expert Centre Chronic Fatigue and Department of General Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands. [E-mail:]