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Differences in physical functioning between relatively active and passive patients with CFS


Senior Member
Differences in physical functioning between relatively active and passive patients with Chronic Fatigue Syndrome.

J Psychosom Res. 2013 Sep;75(3):249-54. doi: 10.1016/j.jpsychores.2013.05.001. Epub 2013 Jun 2.

Vos-Vromans DC, Huijnen IP, Köke AJ, Seelen HA, Knottnerus JA, Smeets RJ.

Revant Rehabilitation Centre Breda, Brabantlaan 1, 4817 JW Breda, The Netherlands. Electronic address: d.vos@revant.nl.



According to the Cognitive behavioral therapy (CBT) protocol for patients with Chronic Fatigue Syndrome (CFS), therapists are advised to categorize patients in relatively active and passive patients.

However, evidence to support the differences in physical functioning between these subgroups is limited.

Using the baseline data from a multicentre randomized controlled trial (FatiGo), the differences in actual and perceived physical functioning between active and passive patients with CFS were evaluated.


Sixty patients, who received CBT during the FatiGo trial were included.

Based on the expert opinion and using the definitions of subgroups defined in the CBT protocols, the therapist categorized the patient.

Data from an activity monitor was used to calculate actual physical functioning, physical activity, daily uptime, activity fluctuations and duration of rest during daily life.

Perceived physical functioning was assessed by measuring physical activity, physical functioning and functional impairment with the Checklist Individual Strength, Short Form-36 and Sickness-Impact Profile 8.


Relatively active patients have a significantly higher daily uptime and show significantly less fluctuations in activities between days.

Passive patients experience a significantly lower level of physical functioning and feel more functionally impaired in their mobility.

However, no significant differences were found in the other actual or perceived physical functioning indices.


A clear difference in actual and perceived physical functioning between relatively active and passive patients with CFS as judged by their therapists could not be found.

Future research is needed to form a consensus on how to categorize subgroups of patients with CFS.

KEYWORDS: Activity monitor, CBT, CFS, Functional impairment, Physical activity, Physical functioning


Senior Member
Shows such sub-divisions have problems in chronic low back pain (CLBP). Also, highlights the problems of relying on self-report measures:
Although categorization of patients is often used in clinical practice, the assumed differences in physical functioning between relatively active and passive patients, as described in clinical protocols, have never been confirmed by measuring the actual daily life activities using an activity monitor.

In patients with chronic low back pain (CLBP), it was found that a subgroup of avoiders, who seem to closely resemble the passive patients, had significantly higher disability levels, a lower perceived daily life activity level, and lower daily uptime compared to a subgroup of persisters [10].

However, no differences in the actual daily life activity level and fluctuations of activities over time could be found. In the CBT protocols for CFS [6,7] experts on CBT state that a patient's perception on physical activity is often distorted by cognitions regarding activity resulting in a discrepancy between what people say and what they actually do.

Therefore, it is important to get insight in the patients' actual level of physical functioning as well as their perceived level of physical functioning, in both subgroups.

These results are in accordance with the results of two studies among patients with CLBP [10,28] who did not find differences in the actual daily life activity level between subgroups of patients either.


Senior Member
They said:

In clinical practice an actometer or other actual activity monitoring system is usually not available because they are too expensive, time-consuming, complex to analyze and difficult to interpret.

Because the CBT protocol is different for passive and relatively active patients with CFS, the CBT therapists were trained before the trial started to categorize the patients.

The therapists didn't have access to the activity monitor data when making the subdivision, but they did have a lot of other data, probably a lot more than clinical practice (these were baseline measurements for a clinical trial).

Classification of patients

During two to three intake sessions, the CBT therapist categorized the patient by questioning the patient about his/her daily activities, using the week list of activities, which the patient had filled in during the week he or she was wearing the activity monitor. Furthermore, the CBT therapists had access to the results of the baseline questionnaires and they were free to use the information in their judgement when categorizing. None of the questionnaires had cut-off scores for categorization of patients with CFS into subgroups. The therapists had access to the results of the questionnaires on depression and anxiety (Hospital Anxiety and Depression Scale) [17], quality of life (SF-36) [16,18], fatigue severity (CIS) [12,13], psychological symptoms (Symptom Check List-90) [19], self efficacy (Self-Efficacy Scale-28) [13], causal attributions (Causal Attribution List) [20] and the impact of disease on both physical and emotional functioning (SIP8) [14,15]. The CBT therapists were instructed to categorize the patient by using the following definitions of relatively active and passive patients with CFS as have been recommended in literature [6,7].

In terms of the SF-36 physical functioning scale:
Median (IQR)
Relatively active: 60 [45.0-72.5]
Passive: 45 [36.3-55.0]

To me, this would mean classifying people who still had a reasonable amount of functioning as passive. Passive meant you weren't encouraged to stabilise at the start of CBT, just increase, which seems problematic. [Although, I question having this approach to any patients].


Senior Member
On the perceived physical functioning, passive patients reported to feel more impaired in their mobility (SIP mobility) and showed lower scores on physical functioning (SF-36) compared to the relatively active patients. This is in accordance with the theory that underlies the CBT protocols [6,7], the results of Van der Werf et al. [2] and Wiborg et al. [29] showing higher functional impairment scores in passive patients. Although perceived physical functioning is lower in passive patients, the actual physical activity level does not show the same pattern when compared to the relatively active patient. There seems to be a discrepancy between the perceived level of physical functioning and the actual daily life activities.
and (from conclusion)
Discrepancies exist between the patient's perception and the actual measure of physical functioning.

Another reason to focus on using objective measures in trials, and doubt subjective measures, one would think.