Just for the record, the following thread was created in the "physical activity & exercise" section but has since been locked and relegated to the "research & funding" section (which do not get answered?) without an answer:
http://www.talkhealthpartnership.com/forum/viewtopic.php?f=490&t=4696
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Where is the evidence that CBT/GET increase activity levels?
Post by biophile.pr on Fri Aug 16, 2013 10:20 am
ME/CFS leads to significant impairments and reductions in a range of activities. [1][2][3]
The underlying rationale of CBT and GET for CFS hypothesizes that these reductions are predominately maintained by cognitive and behavioural factors. Therapy challenges the supposedly maladaptive belief that activity is harmful, and encourages a gradual increase in patients' activity levels. [4]
Promotion of these "rehabilitative" therapies commonly implies or presumes there is good evidence that patients are actually managing to increase their total activity levels substantially, that it is completely safe to do so gradually, and that patients were clearly wrong to fear it in the first place.
However, the evidence from the PACE Trial and similar studies suggests otherwise.
PACE demonstrated a Number Needed to Treat of 1 in 7 to report a (post-hoc weakened definition of) "clinically useful difference" e.g. ≥ 2/33 points in fatigue and 8/100 points in physical function, due to receiving CBT or GET adjunctive to the generic "specialist medical care" provided to all participants. [5] Strictly speaking, the Chalder fatigue scale is not a direct measure of total activity levels, nor is the physical function subscale of the SF-36 health survey which measures self-reported impairments.
The threshold for a "normal" physical function outcome in the PACE Trial was regarded as "significant disability" in the trial eligibility criteria and is what other CBT/GET researchers have described as reflective of significant or even "severe" disability/problems. [6][7][8]
Furthermore, there was no (statistically and/or clinically) significant improvements to the already poor six-minute walking test distances (not a direct measure of total activity levels) [5], total service usage/costs, sickness-related benefits, employment losses, unemployment benefits, or medical insurance payouts. [9]
One (albeit imperfect) method for detecting total physical activity levels is the actometer, a small watch-sized device. Data from multiple European studies, on a style of CBT which includes GET, demonstrated no therapeutic increases to objectively measured reductions in physical activity levels, despite self-reported improvements. [10] This discrepancy between measures is particularly noteworthy for the non-blinded trials which make up the evidence-base for CBT and GET, including PACE.
So if CBT and GET on average do not actually increase total activity levels or increase engagement in other normal life activities, why is it still being promoted as doing so, and is this not encouraging false expectations about prognosis and the nature of improvements attributed to CBT/GET?
Adverse effects with CBT and GET have commonly been reported in patient surveys, and reporting of adverse effects in RCTs of these therapies were generally rather poor before the PACE Trial [11], which demonstrated that it is relatively safe (when safety means it is OK to experience a few weeks of PEM at a time after exercise) to carefully encourage broadly-defined CFS patients to gradually increase activity.
But it is this careful encouragement which appears to be "safe", not increases in total activity levels per se. So although there is something about CBT/GET which apparently helps a small minority of patients report less severe symptoms on questionnaires, claiming that CBT/GET increases total activity levels would not only go beyond the available evidence but even contradict it.
In a recent study on the positive and negative experiences of these therapies, the positive experiences were associated with sensitive delivery of therapy rather than substantial increases in function, and the negative experiences were associated with insensitive delivery of therapy. [12]
Is it therefore possible that the safety of these therapies depends not just on avoiding pushing too hard too fast i.e. so-called "boom-bust", but also on avoiding significant increases in total activity levels, because patients were generally correct about an activity ceiling hindering functional rehabilitation? Even if the occasional patient manages to become somewhat fitter or more physically active, there is still the risk of activity substitution, where these increases come at the cost of other more important activities.
1.
http://www.ncbi.nlm.nih.gov/pubmed/21166613
2.
http://www.ncbi.nlm.nih.gov/pubmed/20943713
3.
http://en.wikipedia.org/wiki/Chronic_fatigue_syndrome#Functioning
4.
http://www.pacetrial.org/trialinfo
5.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3065633
6.
http://www.ncbi.nlm.nih.gov/pubmed/22354999
7.
http://www.ncbi.nlm.nih.gov/pubmed/22865100
8.
http://www.ncbi.nlm.nih.gov/pubmed/19689970
9.
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040808
10.
http://www.ncbi.nlm.nih.gov/pubmed/20047707
11.
http://www.iacfsme.org/BULLETINFALL2011/Fall2011KindlonHarmsPaperABSTRACT/tabid/501/Default.aspx
12.
http://www.ncbi.nlm.nih.gov/pubmed/23735013