Up to 1 million Americans and 2.6 percent of the global population are estimated to have chronic fatigue syndrome, and for decades, the illness has been trivialised due to a lack of scientific evidence supporting its diagnosis.

But for those living with the disorder, the effects can be profound, and now an investigation into the two most commonly prescribed treatments - psychotherapy and exercise (seriously) - has found that they’re being recommended based on some seriously shoddy science.

If you happen to be diagnosed with chronic fatigue syndrome, chances are you’ll be given two recommendations from your doctor - exercise more, or find a good psychotherapist.

Despite the fact that we now have scientific evidence that chronic fatigue syndrome is in fact a biological disorder - and not a psychological condition - researchers have struggled to find treatments to match our updated understanding of the disease.

That means doctors have little choice but to continue recommending what appears to be the best course of action, based on a 2011 study published in The Lancet.

According to that paper - nicknamed the PACE trial, and led by a researcher from the Queen Mary University of London - if you choose to engage in either psychotherapy or exercise, you will have a 60 percent chance of seeing some improvement in your chronic fatigue, and a 20 percent chance of recovering outright.

Those are pretty good odds, right? You’d have to feel pretty crappy about your lot in life if neither of them yielded any results at all.

Well, it turns out a whole lot of people with chronic fatigue syndrome (now often referred to as myalgic encephalomyelitis or ME/CFS) have been feeling pretty crappy about the success (or lack thereof) of their recommended treatments, and headlines like, "Got ME? Just get out and exercise, say scientists," from the Independent haven’t helped.

And it can all be tied back to the results of that 2011 PACE trial, which followed 641 patients for a total of 52 weeks to assess the affects of cognitive behaviour therapy and graded exercise therapy.

As Julie Rehmeyer, who has chronic fatigue, writes for STAT:

"[P]atients like me were immediately skeptical, because the results contradicted the fundamental experience of our illness. The hallmark of ME/CFS is that even mild exertion can increase all the other symptoms of the disease, including not just profound fatigue, but also cognitive deficits, difficulties with blood pressure regulation, unrestorative sleep, and neurological and immune dysfunction, among others. ... Furthermore, the researchers weren’t recommending ordinary psychotherapy - they were recommending a form of cognitive behavior therapy that challenges patients’ beliefs that they have a physiological illness limiting their ability to exercise. Instead, the therapist advises, patients need only to become more active and ignore their symptoms to fully recover. In other words, while the illness might have been triggered by a virus or other physiological stressor, the problem was pretty much all in our heads."

The disconnect between medical advisors and patients had become so great thanks to that $8 million PACE trial, that a group of patients - Rehmeyer included - launched a five-year investigation into its results.

Their request? They simply wanted to see the raw data behind the findings, because they couldn’t understand how the results of a big, controlled, peer-reviewed study could clash so fundamentally with their own experience.

Following several Freedom of Information Act requests to gain access to the trial data, the Queen Mary University of London refused, and it was only after a number of court orders that patients finally got access to them.

The truth that the university wanted to conceal? When independent scientists analysed the raw data, they found that if you’re already getting standard medical care, your chances of being helped by exercise and psychotherapy are - best case scenario - 10 percent.

Chances of recovery were found to be less than 5 percent for the exercise group, and less than 7 percent for the therapy group. And, unlike the improvement statistics, the recovery statistics weren't even statistically significant.

A far cry from the 60 and 20 percent figures that were actually published.

"This is a classic bad study," Ron Davis, director of the Stanford Genome Technology Centre and director of the Science Advisory Board of the End ME/CFS Project, told STAT.

"The study needs to be retracted," he added. "I would like to use it as a teaching tool, to have medical students read it and ask them, 'How many things can you find wrong with this study?'"

So where did it all go so wrong?

Davis says one of the biggest problems is that the study used such a broad definition of chronic fatigue syndrome that it likely included many patients who didn’t actually have it, which would have of course skewed the results.

The definitions of "recovery" and "improvement" also changed significantly during the course of the trial, and 'proof' that patients felt better was based on nothing but self-reporting.

"They found no significant improvement on any of their objective measures, such as how many patients got back to work, how many got off welfare, or their level of fitness," Rehmeyer reports.

There's a whole lot more here, but the results of the independent analysis have been published on the Virology Blog - hosted by Columbia microbiology professor Vincent Racaniello - so you can go through the details with a fine-toothed comb.

To be clear, this analysis has not been formally peer-reviewed, but the researchers say the onus is now on the original PACE trial team to respond to their findings.

"[I]t is now up to the PACE authors to explain why anyone should accept their published outcomes as accurate, reliable or legitimate," they conclude.

The sad truth is that even if official corrections are made, and even if the paper is retracted - something that only happens very rarely - the damage has already been done, and it's going to take a whole lot to change long-established misconceptions about a disease so debilitating.

Let's hope future research into chronic fatigue will be backed in far better science.