Prognosis for myalgic encephalomyelitis and chronic fatigue syndrome

Prognosis refers to the expected course of a disease and the prospect of recovery. In ME/CFS prognosis is considered to be poor with only a minority (a median estimate of 5%) returning to pre-morbid levels of functioning. The majority of patients remain significantly impaired. A substantial improvement however is noted in an estimated 40% of patients and the prognosis in adolescents is considered to be better than in adults.

Due to heterogeneity in methodology such as case definition, length of follow-up and assessment of recovery, the estimated prognosis of ME/CFS is variable and uncertain. According to ME-expert Charles Shephard “there is a wide spectrum of severity, variability and degrees of improvement and deterioration in ME/CFS – and so prognosis can very difficult to predict with any certainty in an individual case."

Follow-up studies
In one of the first extensive studies on the prognosis of ME/CFS, Peterson et al. studied 65 patients who fulfilled the Holmes criteria after a one-year follow up. Though 40% reported improvement, none of the patients considered themselves recovered. Similar results were reported by an Australian team in 1994. They followed-up on 103 patients for 3,2 years. Although the majority reported improvement, less than 6% had completely recovered. Two years later, a Dutch research team from Nijmegen published results for their large sample of 246 ME/CFS patients. After a 1,5 year follow-up only 3% said they had recovered and only 17% reported improvement. The first report on prognosis using the Fukuda-criteria was published by Szalstein et al. Because they studied ME/CFS patients in primary care, recovery rates were generally higher, around 20%. In 2017 Collin & Crawley reported the prognosis of 418 ME/CFS patients treated in a British ME/CFS centre and diagnosed according to the NICE-criteria. Two and a half years later less than 6% reported they no longer suffered from ME/CFS and 30% claimed their health had deteriorated. All of the aforementioned studies used different diagnostic criteria – the Holmes, Australian, Oxford, Fukuda and NICE-criteria respectively – but reported similar poor outcomes, with only a tiny minority of ME/CFS reaching full recovery.

Community-based studies
The poor prognosis observed in tertiary and primary care was confirmed by the epidemiological study in Chicago. Of the 32 ME/CFS patients identified in the late 1990s 24 were evaluated after a period of approximately 10 years. Of these, two thirds continued to have ME/CFS, 21% had developed exclusionary illnesses, 8% was now labeled as suffering of idiopathic chronic fatigue and only 4% had remitted.

Work-related outcomes and objective measures
Although research has generally used self-reported improvement to estimate prognosis, some studies included more objective measurements such as work-related outcomes. These have generally reported less improvement. Vercoulen et al. and Hill et al. for example found no significant change in employment status. Another study from the group of Benjamin Natelson found that unemployment rates increased after 3,5 year follow-up. A Danish study followed up on 33 patients for an extensive period of 5 years. Though work disability was already high at baseline (77%), this increased even further to 91%. A trend towards a decrease in employment status was also reported  by Collin & Crawley, as more patients reported a deterioration than an improvement in hours spent on work, education and social activities (see table).

Other studies have shown that ME/CFS patients do experience improvement on objective measures. Tiersky et al. for example noted better results on neurocognitive testing after a period of 3,5 years. Rowe et al. reported a significant improvement in range of motion (ROM) in 53 adolescents with ME/CFS after a 2 year follow-up.

The CDC’s optimistic prognosis
Despite heterogeneity in diagnostic criteria and patient sample, most research is in agreement on the poor prognosis in ME/CFS (see table below). Research by the Centers for Disease Control and Prevention (CDC) however has controversially reported much higher recovery rates. The CDC-surveillance system for example reported a “cumulative probability of recovery” from ME/CFS of 31,4% during the first 5 years of illness and 48.1% during the first 10 years of illness. Data from the epidemiological research in Wichita, Kansas indicated even higher recovery rates. At the 3 year follow-up almost 80% no longer fulfilled the diagnostic criteria for ME/CFS, though a large minority (23,1%) were diagnosed with other diseases such as sleep disorders. More than half of the studied ME/CFS patients had experienced partial to total remission during follow-up. The CDC information webpage has been criticized by patient organizations for painting the prognosis of ME/CFS in a positive light and overemphasizing natural recovery of the disease. ME Action for example wrote:"“While presenting a more positive outlook may decrease physician discomfort in dealing with a chronic and debilitating disease like ME, it is disingenuous to imply that patients will return to good health when so few do. Moreover, this can delay patients from getting the social support they need to cope with a lifelong illness.”"

Outbreaks
Longitudinal studies on ME-outbreaks show that in its epidemic form, the disease tends to have a better prognosis. This might be because less strict diagnostic criteria were used in these studies or because patients were followed-up much earlier in their disease process (bypassing the normal 6 month waiting period). Levine et al. provided follow-up data from the outbreaks in the Nevada-California region (Incline Village, Truckee, Yerington and Placerville) during the 1980s. 29 patients were revaluated after a period of 3 years. Almost all subjects were able to return to pre-illness activity and the authors concluded that the overall prognosis was generally favorable."“Among the patients we observed were a marathon runner, a marathon bicyclist, avid skiers, mountain climbers, and other individuals pursuing an unusually physically active life-style prior to their acute illness. All of these patients attempted to continue their activities and most of them, after periods ranging from 6 to 18 months, eventually were able to resume their previous activities.”"Another follow-up study however, concluded that only an estimated 41% of patients during these outbreaks would fulfill the Holmes criteria of ME/CFS. The recovery rate for these ME/CFS patients was only 15%, much lower than the 30% for all patients of the Lake Tahoe outbreak.

A 10 year follow-up of the outbreak at West Otago, New-Zealand also reported a good prognosis. Though some needed to adapt their lifestyle to prevent relapses, most patients returned to premorbid activity.

Follow-up data is also available for the outbreak in Akureyri, Iceland. Sigmundsson reported in 1955 that 13% of the patients he evaluated considered themselves completely recovered. In 1988 Byron Hyde reported about 10 Icelandic ME-patients in the Lancet, 40 years fate the initial outbreak. Two of them (20%) indicated a “total physical and intellectual recovery”.

Pediatric
Prognosis in adolescents with ME/CFS is generally considered to be more favorable than in adults. Gill et al. reported that 4,5 years after an initial evaluation almost a quarter of adolescent ME/CFS patients reached “near to complete improvement”. The diagnosis in this study however was made retrospectively (by looking at old charts and test results instead of a clinician’s assessment). A Dutch team followed up on 54 adolescents with ME/CFS. After an average of 2,2 years almost half of the sample said they’ve had almost completely recovered. Other studies (Rangel et al., Sulheim et al. Bell et al., Rimes et al.) have reported similar high improvement/recovery rates in pediatric ME/CFS, though these studies did not use generally accepted diagnostic criteria. In the Bulletin of the IACFS-ME Katherine Rowe claimed to have data for 256 young ME/CFS patients 12 years after initial evaluation. 88% reported recovery, though this information has not been reported in a peer-review publication. In its 2015 report, the National Academy of Medicine noted a lack of well-designed longitudinal studies on the prognosis of ME/CFS in children and adolescents (P 183 and 213).

Disease onset and lifelong illness
The disease ME/CFS is diagnosed when a person does not recover from a flu-like illness, EBV, mononucleosis, HHV, Q fever, virus or other infections and meets one or more diagnostic criteria for either myalgic encephalomyelitis (ME), chronic fatigue syndrome (CFS) or ME/CFS. "Occasionally, ME/CFS has been triggered by environmental toxins, the receipt of an immunizing injection, or surviving a major trauma." Patient health is never the same and they experience numerous symptoms and disease severity which fluctuate day to day, week to week, month to month, year to year and decade to decade as well as varying symptoms and disease severity among patients.

Severely ill
It is estimated that 25% of ME/CFS patients are severely ill and are housebound or bedbound.

Learn more

 * Lecture by Dr. David Bell, April 16, 2011