Whether or not people with ME/CFS die earlier, for whatever reason, than the general population is an important question, and there are few good clues to the answer in the scientific literature.
One analysis of information on 166 deceased patients in a memorial list kept by the National CFIDS Foundation in the USA found three of the most prevalent causes of death to be heart failure, suicide and cancer – valuable findings, but impossible to generalise to the overall population of patients with ME/CFS, as the authors made clear (read more). Another study, from the National Cancer Institute, of people aged 66 years and older, interrogated cancer data from registries across the USA and found that the overall risk of cancer was not increased in those with a diagnosis of CFS. There was, however, a small increased risk of non-Hodgkin lymphoma which was “likely too small to affect the clinical management of patients” (read more). Other studies have examined prognosis and outcomes in ME/CFS (Joyce 1997; Cairns 2005; Jason 2011; and Smith 2006), but none have uncovered convincing evidence that mortality is increased compared with the general population.
A new study just published in the Lancet, the largest examination to date of outcomes in patients from the UK, tends to confirm these findings for overall mortality (read more). In the study, researchers at King’s College London used data-mining techniques to examine the medical records of 2147 people with ME/CFS who had been referred by their GPs to the CFS service in London. Over a 7-year period (2007–2013), only 17 of the patients had died: 8 from cancer, 5 from suicide, and 4 from other causes. When these mortality rates were compared with matched population data from the Office of National Statistics, the overall rate of deaths from all causes was no higher in ME/CFS patients than in the general population, and there was no difference in the rate of deaths from cancer. These findings will come as a relief to many patients and their families, particularly those who have been ill for many years.
The aspect of the data that has caught the attention of the media, however, concerns suicide. The 5 suicides in the ME/CFS group were more than would have been expected in the general population (<1 in a study population of 2147). In statistical terms, this means that the rate of deaths by suicide was increased by around 6.85-fold, allowing media headlines to chirrup that suicide was six times more likely in ME/CFS patients than in the general population (see an example). The authors themselves are more cautious, however, pointing out that the absolute number of deaths by suicide was small, and that the rate was far lower than in some other disorders. An expert commentary (which is well worth reading) accompanying this Lancet study highlighted the difficulty of interpreting this finding – “The increased suicide mortality…was based on just a few deaths and the confidence intervals were wide. Two fewer suicide deaths [i.e. 3 instead of 5] would have meant that the findings were no longer significant.” – and stressed the need for caution given the small numbers involved and the number of confounding factors that could be influencing the result. In essence, the increased suicides rate may be a true finding (as the authors say, “it is highly unlikely that the result is due to chance”), but far larger numbers of patients would be needed for cast-iron certainty.
Assuming that the small but significant increase in suicide is real, would it really be a surprise? ME/CFS patients make up a distinct group of chronically ill people, and chronic illnesses (such as multiple sclerosis, chronic pain, epilepsy, the heart diseases, etc.) are well know to be risk factors for suicide, particular in older adults (read more). Importantly, suicide in the chronically ill is also linked with co-existing depressive illness – and in this Lancet study too, the risk of death by suicide was independently associated with a lifetime diagnosis of depression. For these reasons, chronicity as well as the appearance of signs of major depression should be red flags for clinicians and healthcare professionals in all long-term illnesses with potentially severe consequences, including ME/CFS.