Uncontrolled study proves little about value of therapy received
Tom P. Kindlon, Information Officer (voluntary position)
Irish ME/CFS Association
This paper (1) includes data on two separate (but related) issues: (i) the prevalence of diagnosed and undiagnosed Chronic Fatigue Syndrome/Myalgic Encephalomyelitis ("CFS/ME") (NICE criteria (2)) in children aged 11-16 and (ii) information on how they fared when they received therapy at the CFS clinic. The relative rigour that is brought to the first set of data may mean some may miss that many questions remain about the therapeutic data, which I will now attempt to elucidate.
Ideally what one would want to know is whether there would have been any difference in outcomes if the children had been neither diagnosed nor treated. The criteria used, the NICE criteria (2), which require fatigue and one other symptom for three months or more, are relatively broad - most other criteria for ME and/or CFS are stricter i.e. they require more symptoms (3-9). A systematic review looking at the prognosis of chronic fatigue and chronic fatigue syndrome found that as the criteria got more stringent, the prognosis worsened (10). A Dutch natural course study found that less fatigue improved the prognosis of CFS (11). A US team noted that CFS patients with higher levels of physical functioning were more likely to report recovery at follow-up (12). This suggests the possibility that the group diagnosed because of the surveillance, who had less severe fatigue and better physical functioning, might have a better prognosis than clinic attenders i.e. data from the latter should not necessarily be extrapolated to the former without adjustment for their less severe illness. The prognosis for many adolescents with CFS is good (13-14).
However, despite these difficulties in estimating the prognosis of patients if they had been given neither a diagnosis nor treatment, I'm inclined to think it is better to give a diagnosis based on existing data. A Centers for Disease Control and Prevention (CDC) study suggested that a delayed diagnosis appeared to be a risk factor for poor prognosis, prompting them to launch a multi-million dollar awareness and education campaign aimed at both clinicians and the general public (15). A study in the UK found that a longer time to diagnosis significantly increased the chances that a person would be severely affected [i.e. it compared those who were mildly affected and those who were severely affected (omitting those who could not easily be classified in either group) and found, even after adjustments, that the time to diagnosis was greater for the severely affected group than the more mildly affected group] (16).
So the more important question in my mind is the value, or otherwise, of therapy received. Unfortunately we don't get that much quantitative data on this. We are told information about children being "fully recovered" without information about how this was defined or indeed who decided they were fully recovered (e.g. clinician, parent, children or a combination of individuals?). An important aspect of this is the number of time points that were used. "CFS/ME" is well-known for often having a relapsing and remitting course, something the CDC found in one of their longitudinal studies (17). Another CDC CFS paper reported (in a study where recovery was self-defined) "at 6 months from first reported recovery, 57% (26/46) of these patients reported that they continued to consider themselves recovered from their fatiguing illness, 28% (13/46) reported a return of their fatigue, and 15% (7/46) had incomplete data on fatigue status following their report of initial recovery" (18). A US paediatrician followed some of his ME/CFS patients into adulthood. In one study, ten persons who considered themselves "recovered" or "nearly recovered" (at the time of the assessment) were given questionnaires to assess health status and compared to healthy adults (19). Half of the "recovered" subjects would be considered ill with CFS based upon the disability requirements of the CDC empiric definition of CFS (a broad definition) (20), and all "recovered" subjects had significant somatic symptoms.
The question of whether patients should be treated, or whether simply diagnosing at this time might be better, is important given the therapies in question: Graded Exercise Therapy (GET) and Cognitive Behaviour Therapy (CBT). I recently published a paper (21) looking at the reporting of harms for GET and CBT (and in particular the form of CBT based on scheduling graded activity, the form recommended by the NICE guidelines to which the clinic adheres (22)). Reporting of harms in RCTs of these therapies has been recognised as being poor by Cochrane Reviews on both therapies along with the systematic review on which the NICE guidelines were based (22- 25). As they are non-pharmacological interventions, no yellow card facility exists for reporting adverse events. In this scenario, data from surveys may be particularly important: a review of 10 surveys I collated found 51% of survey respondents (range 28-82%, n=4338, 8 surveys) reported that GET worsened their health while 20% of respondents (range 7-38%, n=1808, 5 surveys) reported similar results for CBT (21). This should raise serious questions about the use of these therapies, particularly on individuals who haven't presented themselves to their doctors but have been picked up by surveillance.
As I said, the information on efficacy in this study (1) is far from ideal given it's uncontrolled. The authors claim the "PACE trial provided strong evidence that these treatments are moderately effective in adults" (1,26). However, this statement is based on subjective outcome measures and previous studies of therapies testing graded activity protocols for CFS have shown that, despite reporting improvements over a control group (27), or over time (28), individuals may not have improved when activity (as measured by actometers) are used as the outcome measure. If one looks at the most objective measure of functioning that has so far been reported in the PACE Trial, the 6 minute walk test (6MWT), there was no difference between the CBT and control group (26). Following adjustment, the GET group did increase by 35 metres over the control group but a final result of only 379m is more like the result of a spavined older adult than the 644m that population norms predict for the participants in the PACE Trial (adults of average age 39 year old adults, 77% of whom are female) (21,26).
So, in conclusion, I'm inclined to believe this study suggests the need for a greater awareness of how prevalent "CFS/ME" can be amongst adolescents. However, whether they should then routinely be treated with CBT and/or GET is still open for debate.
References:
(1) Crawley EM, Emond AM, Sterne JA. Unidentified Chronic Fatigue Syndrome/myalgic encephalomyelitis (CFS/ME) is a major cause of school absence: surveillance outcomes from school-based clinics. BMJ Open. 2011 Dec 12;1(2):e000252. Print 2011.
(2) NICE. Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (or Encephalopathy); Diagnosis and Management. CG53. London: National Institute for Health and Clinical Excellence (NICE), 2007.
(3) Carruthers B, Jain A, de Meirleir K, Peterson D, Klimas N, Lemer A, et al.: Myalgic encephalomyelitis/chronic fatigue syndrome: clinical working case definition, diagnostic and treatment protocols. J Chronic Fatigue Syndrome 2003;11(1):7-33
(4) Jason LA, Bell DS, Rowe K, Van Hoof ELS, Jordan K, Lapp C, Gurwitt A, Miike T, Torres-Harding S, De Meirleir K. & IACFS. A pediatric case definition for ME/CFS. J Chronic Fatigue Syndr. 2006;13(2/3):1-44.
(5) Fukuda K, Straus SE, Hickie I, Sharpe MC, Dobbins JG, Komaroff A. The chronic fatigue syndrome: A comprehensive approach to its definition and study. Annals of Internal Medicine. 1994;121:953-959.
(6) Holmes GP, Kaplan JE, Gantz NM, et al. Chronic fatigue syndrome: a working case definition. Ann Intern Med. 1988 Mar;108(3):387-9.
(7) Jason LA, Evans M, Porter N, et al. The development of a revised Canadian Myalgic Encephalomyelitis-Chronic Fatigue Syndrome case definition. American Journal of Biochemistry and Biotechnology. 2010:6;120 -135.
(8) Carruthers BM, van de Sande MI, De Meirleir KL, Klimas NG, Broderick G, Mitchell T, Staines D, Powles AC, Speight N, Vallings R, Bateman L, Baumgarten-Austrheim B, Bell DS, Carlo-Stella N, Chia J, Darragh A, Jo D, Lewis D, Light AR, Marshall-Gradisbik S, Mena I, Mikovits JA, Miwa K, Murovska M, Pall ML, Stevens S. Myalgic encephalomyelitis: International Consensus Criteria. J Intern Med. 2011;270:327-38. doi: 10.1111/j.1365-2796.2011.02428.x. Epub 2011 Aug 22.
(9) Jason LA, Damrongvachiraphan D, Hunnell J, Bartgis L, Brown A, Evans M, Brown M. Myalgic Encephalomyelitis: Case definitions. Autonomic Control of Physiological State and Function. 2012. 1, 1-14. doi:10.4303/acpsf/K11060. Available at:
http://www.ashdin.com/journals/ACPSF/K110601.pdf Accessed Dec. 30, 2011.
(10) Joyce J, Hotopf M, Wessely S. The prognosis of chronic fatigue and chronic fatigue syndrome: a systematic review. QJM. 1997 Mar;90(3):223 -33.
(11) Vercoulen JH, Swanink CM, Fennis JF, Galama JM, van der Meer JW, Bleijenberg G. Prognosis in chronic fatigue syndrome: a prospective study on the natural course. J Neurol Neurosurg Psychiatry. 1996 May;60(5):489- 94.
(12) Pheley AM, Melby D, Schenck C, Mandel J, Peterson PK: Can we predict recovery in chronic fatigue syndrome? Minnesota Medicine 1999, 82(11):52-6.
(13) Rimes KA, Goodman R, Hotopf M, Wessely S, Meltzer H, Chalder T. Incidence, prognosis, and risk factors for fatigue and chronic fatigue syndrome in adolescents: a prospective community study. Pediatrics. 2007 Mar;119(3):e603-9.
(14) Katz BZ, Shiraishi Y, Mears CJ, Binns HJ, Taylor R. Chronic fatigue syndrome after infectious mononucleosis in adolescents. Pediatrics. 2009 Jul;124(1):189-93.
(15) Reyes M, Nisenbaum R, Hoaglin DC, Unger ER, Emmons C, Randall B, Stewart G, Abbey S, Jones JF, Gantz N, Minden S, Reeves WC. Prevalence and incidence of chronic fatigue syndrome in Wichita, Kansas. Archives of Internal Medicine 2003;163:1530-1536.
(16) Pheby D, Saffron L. Risk Factors for Severe ME/CFS. Biology and Medicine. 2009;1:50-74.
(17) Nisenbaum R, Jones JF, Unger ER, Reyes M, Reeves WC. A population-based study of the clinical course of chronic fatigue syndrome. Health Qual Life Outcomes. 2003 Oct 3;1:49.
(18) Reyes M, Dobbin JG, Nisenbaum R, Subedar N, Randall B, Reeves WC: Chronic fatigue syndrome progression and self-defined recovery: evidence from CDC surveillance system. Journal of Chronic Fatigue Syndrome 1999 5(1):17-27.
(19) Bell DS, Bell DE. Definition of recovery in Chronic Fatigue Syndrome. The Journal of IiME. 2010. 4 (1) 23-27
(20) Reeves WC, Wagner D, Nisenbaum R, Jones JF, Gurbaxani B, Solomon L, Papanicolaou DA, Unger ER, Vernon SD, Heim C. Chronic fatigue syndrome- -a clinically empirical approach to its definition and study. BMC Med. 2005;3:19.
(21) Kindlon T. Reporting of Harms Associated with Graded Exercise Therapy and Cognitive Behavioural Therapy in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Bulletin of the IACFS/ME. 2011;19(2):59-111.
http://www.iacfsme.org/BULLETINFALL2011/Fall2011KindlonHarmsPaperABSTRACT/tabid/501/Default.aspx
(22) NICE. Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (or Encephalopathy); Diagnosis and Management. CG53. London: National Institute for Health and Clinical Excellence (NICE), 2007.
(23) Price JR, Mitchell E, Tidy E, Hunot V. Cognitive behaviour therapy for chronic fatigue syndrome in adults. Cochrane Database Syst Rev. 2008;(3):CD001027.
(24) Edmonds M, McGuire H, Price J. Exercise therapy for chronic fatigue syndrome. Cochrane Database Syst Rev. 2004;(3):CD003200.
(25) Chambers D, Bagnall AM, Hempel S, Forbes C. Interventions for the treatment, management and rehabilitation of patients with chronic fatigue syndrome/myalgic encephalomyelitis: an updated systematic review. J R Soc Med. 2006;99:506-20. Review.
(26) White P, Goldsmith K, Johnson A, et al. Comparison of adaptive pacing therapy, cognitive behaviour therapy, graded exercise therapy, and specialist medical care for chronic fatigue syndrome (PACE): a randomised trial. Lancet 2011;377:823e36.
(27) Wiborg JF, Knoop H, Stulemeijer M, Prins JB, Bleijenberg G. How does cognitive behaviour therapy reduce fatigue in patients with chronic fatigue syndrome? The role of physical activity. Psychol Med. 2010;40:1281 -1287.
(28) Friedberg F, Sohl S. Cognitive-behavior therapy in chronic fatigue syndrome: is improvement related to increased physical activity? J Clin Psychol. 2009;65:423-42.
Conflict of Interest:
I am Information Officer of the Irish ME/CFS Association. All my work for the Association is voluntary (i.e. unpaid)