CDC Study Must Include CPET, NK Cell and Viral Testing, Advocates Insist

Mark Berry invites readers to join 11 organizations and 31 advocates and write to the CDC, asking them to include appropriate medical tests in their multi-site study.

Federal government ignoresThe historical approach of the US Centers for Disease Control and Prevention (CDC) to the study of ME/CFS has not been universally well-received – and that’s an understatement. The majority opinion of the ME/CFS community seems to be that the CDC has had its head stuck in the sand, as far as ME/CFS is concerned, ever since CDC epidemiologists finally rolled into Lake Tahoe to investigate the outbreak there in 1984. But in recent years there have been some promising signs that the CDC may at last be starting to take the disease more seriously.

The CDC’s multi-site, multi-phase clinical assessment study aims to “describe the differences and similarities among CFS patients,” “improve how we measure illness domains of CFS,” “address the CFS case definition,” and possibly allow patients “to be sub-grouped to improve therapy and allow the underlying biology to be discovered.”

Such a large study, led by a federal agency, represents a major opportunity for patients, both in the United States and around the world. There is at least a chance that it might bring some much-needed clarity to the questions and problems surrounding case definitions and subsets which have dogged ME/CFS research for decades.

So it’s a very important study for ME/CFS patients, and it’s important too for the credibility of the CDC, so badly damaged in the eyes of the patient community by the scandal over the diversion of funds allocated for ME/CFS research – not to mention more than 25 years of failure to make meaningful progress in the study of an illness that blights the lives of millions of patients. The CDC study is already collecting a mountain of data – but in research, what answers you can find depends on the questions you ask, and the data you collect…and there, it appears, we may have a problem…

Missing Information

Although the study has already collected a vast array of data on clinical history and demographics, and patients have filled in a long list of questionnaires, so far there’s been a worrying lack of tests that could help confirm biological abnormalities in ME/CFS patients. More worrying still, at the last CFSAC meeting in May 2013, Dr Unger appeared to indicate resistance to the idea of conducting the very tests that many consider crucial to understanding the nature of the pathology in ME/CFS.

Repeat exercise testing is considered by many to be the fundamental test necessary to confirm post-exertional malaise – widely seen as the cardinal symptom of ME/CFS – but is the CDC prepared to conduct the tests necessary to demonstrate it, or will it deploy other tests that are known to miss this crucial phenomenon? Simon McGrath reported on Dr Chris Snell’s recent study of CPET abnormalities earlier this week – both Keller and Vemeulen have also confirmed what many practitioners and patients know from long experience: repeat testing is necessary to demonstrate the distinctive effects of exercise on ME/CFS patients. This finding may be in tune with patients’ subjective experiences, but it does need further confirmation in larger studies. What better opportunity than the CDC’s large-scale study to explore this crucial question?

A wealth of research has also highlighted the significance of viral infections and immune dysfunction in ME/CFS, but will the CDC even measure NK Cell Function and test for viruses associated with ME/CFS?

It is far from clear that the CDC intends to ask any of these questions: the detail so far on the promised blood testing seems vague at best. And with the CDC having already admitted that their study has not yet found a way to study any of the most severely affected housebound and bedbound patients, there’s a considerable risk that the CDC’s study may fail to study ME at all – a frightening prospect if its conclusions are going to be interpreted and applied as if they had done so.

What hope is there for a useful outcome from this study if the CDC fails to assess the most promising candidates for biomarkers discovered in the last 20 years of ME/CFS research? What chance that the research will help to restore common understanding to a fractured field if it excludes the most promising tests indicated by the work of ME/CFS researchers? Do the study’s findings, and any recommendations for case criteria which may result from it, have a realistic chance of being respected and accepted, rather than opposed by the patient and advocacy community, if the study fails to ask the very questions that many patients, advocates and researchers consider to be the most crucial?

The danger that this study may become yet another missed opportunity – or worse, bury the reality of a serious illness even deeper below a mountain of obfuscation – seems very real to many advocates, who are disturbed by the apparent intention of the CDC to exclude crucial evidence from the study.

Letter to the CDC

Change Request FormWith these concerns in mind, on July 22nd, 11 patient organizations (including Phoenix Rising) and 31 patient advocates wrote to Dr Unger, Secretary Sebelius, Dr Koh, Dr Frieden, the sites participating in the CDC study and their clinicians, and the members of CFSAC, urging them not to rely on self-reported measures but to include objective measurements in their study. Specifically, the letter calls for the inclusion of 2-day Cardiopulmonary Exercise Testing or CPET (using the Stevens Protocol) and laboratory tests to measure Natural Killer Cell function and viral load, including enteroviruses.

The letter includes an extract from the CFS Advisory Committee meeting of May 2013, reminding Dr Unger of the testimony of Fred Friedberg that post-exertional malaise is “uniquely important” in the essence of this illness, and of Steve Krafchick who said that he would “get down on his knees and plead” with Dr Unger for the integration of neuro-psych testing and CPET into the study because it represents “the most objective evidence that you could ever hope to get”, adding: “patient report is nice, and it’s cheap, but if we’re trying to do what you said you were trying to do – don’t miss this opportunity please.”

Also included with the letter are academic references in support of the call for the use of CPET, and the list of organizations and advocates who signed it. You can read the letter and supporting information here, and the letter sent to clinicians is available here.

The letter’s conclusion sums up its message: “Objective, biological measurements are vital in order to describe the differences and similarities among patients, determine how we characterize and treat patients, address the case definition issues, educate our medical community, and further our understanding of the underlying biology of ‘CFS’.  For that reason, we urge you to consider incorporating these important tests as soon as possible”.

“Please know that we are willing to do everything within our power to work with you and the clinicians involved in order to accomplish this crucial goal. Like you and your colleagues, we want this study to be a success.”

So: A wide range of organizations and patient advocates have spoken. Over now to Dr Unger and the CDC: are they prepared to test ME/CFS patients for biological abnormalities, or are their heads still stuck firmly in the sand?

How to Add Your Voice

11 organizations and 31 patient advocates have spoken – now we urge the wider ME/CFS community, including non-US residents, to add their voice and add to the pressure on the CDC to include these objective measurements in their study.

Erica Verillo has produced the following template letter – a shorter version of the letter already sent to Dr Unger – which you can use to add your voice in support of this campaign. Please feel free to edit it and add your own comments…and to indicate your support for the letter on the discussion thread below this article…


Elizabeth Unger, PhD, MD, Chief of the Chronic Viral Diseases Branch

Centers for Disease Control and Prevention (CDC)

1600 Clifton Road

Atlanta, GA 30333


Dear Dr. Unger,

In 2012, the CDC initiated a multi-site, multi-phase clinical assessment study to describe the differences and similarities among ME/CFS patients, determine how we characterize and treat patients, implement an accurate case definition, educate our medical community, and further our understanding of the underlying biology of ME/CFS.

Because the CDC’s multi-site study represents a major opportunity to make a difference for patients – both in the United States and around the world – objective, biological measurements are vital. However, a clinical investigation that does not include proper methodology to obtain objective data will fail to achieve its goals and will result in lost time, lost investment, and worst of all, lost opportunity.

It is absolutely essential that the CDC study include two objective tests which have consistently revealed abnormalities in ME/CFS patients. These tests are:

1)     The two-day Cardiopulmonary Exercise Test (CPET). The two-day CPET provides gas exchange and other objective and measurable results “which can’t be faked.” Numerous studies have shown that the 2-day CPET – as opposed to the 1-day CPET – is a reliable and consistent method for measuring post-exertional malaise (PEM), the hallmark symptom of ME/CFS. This test can be done employing technology which has been used in hospitals for decades.

2)     Low Natural Killer Cell Function/Viral Load. Abnormally low NK Cell activity and high viral loads are consistent findings in patients with ME/CFS. These tests can be done in many labs around the country and will provide objective, measurable data for comparison purposes.

Measuring and understanding post-exertional malaise (PEM) is crucial to this study. PEM is not only the primary symptom that distinguishes ME/CFS from depression, deconditioning, and other fatiguing illnesses, it is the ME/CFS sufferer’s main obstacle to daily activities, gainful employment, and leading a normal life.

Please include the 2-day CPET and tests for NK-Cell function and viral load in the CDC’s multi-site study.

Thank you,

(Your name, City and State, or Country)



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