Comment on: Chronic fatigue syndrome: a follow up study. [J Neurol Neurosurg Psychiatry. 1994]
Chronic fatigue syndrome: a follow up study by Bonner et al’ reported that 47 patients initially diagnosed with “chronic fatigue” were contacted for follow up four years later. The authors indicated that “These patients were initially assessed before the current criteria for chronic fatigue syndrome became available, but most would have satisfied the criteria retrospectively” (p 617). At the outset, all patients were offered cognitive behavioural treatment and some were offered antidepressant medications. Each patient then made a decision to either undergo or decline cognitive behavioural treatment. Four years later, those patients who reported functional improvement were more likely to have elected to receive the cognitive behavioural treatment. Additionally, patients in the group that did not report any functional improvement were more likely to score higher on measures of depression.
The US Centers for Disease Control and Prevention (CDC) case definition,2 the proposed revisions to the CDC case definition,3 and the guidelines for research set forth by Sharpe et al4 were cited, but the researchers did not make it clear as to which criteria were used to diagnose which patients. Thus it is unknown whether uniform criteria were applied to diagnose all patients at the outset. Moreover, the authors did not specify just how many of the initial 47 patients met any of the cited criteria for chronic fatigue syndrome, as opposed to chronic fatigue. In short, they did not differentiate the exact number of chronic fatigue syndrome v chronic fatigue cases.
Only 29 of the original 47 patients (62%) agreed to be interviewed for the follow up. Thus 18 (38%) of the original patients were not included in the outcome data, where 10 subjects reported little or no improvement and 19 subjects reported improvement or recovery. The authors acknowledged that the small patient sample size constituted a methodological shortcoming, but nevertheless concluded “that there is a strong association between successful completion of [cognitive] treatment and the absence of functional disability at the four year follow up” (p 620). They further suggest that costs associated with long term disability could be reduced by the utilisation of cognitive therapy in the treatment of chronic fatigue syndrome. We would like to emphasise that the small patient sample size, together with the lack of availability of almost 40% of the initial patients for interview at follow up, make such conclusions highly inappropriate.
You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1073573/pdf/jnnpsyc00030-0116.pdf
Source: Lipkin DM, Robin R, Vasquez L, Plioplys AV, Plioplys S. Chronic fatigue syndrome. J Neurol Neurosurg Psychiatry. 1995 Jun;58(6):764-5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1073573/