Contrary to conventional wisdom, patients with chronic fatigue syndrome respond to placebos at a lower rate than people with many other illnesses, according to the first systematic review of the topic.
According to the new analysis by Dr. Hyong Jin Cho of King's College London and colleagues, 19.6 percent of patients with chronic fatigue syndrome improved after receiving inactive treatments, compared with a widely accepted figure of about 30 percent for other conditions.
Because the placebo effect seems to be strongest in diseases with highly subjective symptoms, some medical professionals believed it could be as high as 50 percent among CFS patients.
The review, reported in the March 2005 issue of Psychosomatic Medicine, pooled data from 29 studies in which 1,016 people with CFS received various placebos.
CFS is a complex illness that has no known cause or cure. Myriad symptoms include severe malaise, muscle and joint pain, sleep and mood disturbances and headache. The symptoms continue for at least six months and cannot be explained by any other medical conditions. The Centers for Disease Control and Prevention estimate that as many as 500,000 Americans may have CFS or related conditions.
With so many mysteries surrounding CFS, a great deal of controversy exists among both doctors and patients as to whether its origins are primarily psychological or physiological. Current evidence suggests that emotional or social stresses such as bereavement or problems at work, combined with other triggers such as common viral infections, contribute to the disorder. Additional factors, such as avoidance of physical activity, may cause the symptoms to become chronic, says Cho.
The authors propose several possible explanations for the surprisingly low placebo response revealed in the analysis. Perhaps patients have low expectations due to the reality that CFS is very difficult to treat and often persists for many years. Alternatively, disconnects between how patients and doctors view the illness "may impede development of a collaborative therapeutic relationship," reviewers suggest.
The study also showed that the placebo response is 24 percent for medical interventions but only 14 percent for psychiatric/psychological treatments. The authors say the reason may be that many CFS sufferers seen in specialist settings or self-help groups "have a firm conviction that their illness is of physical origin" and thus would have little faith in psychiatric/psychological treatments. This finding supports the idea that the placebo response is greatly influenced by patients' expectations of improvement.
According to the review, behavioral therapy and graded exercise therapy have benefits, and if patients were more aware of them, says Cho, they might be "more open, more optimistic, and more collaborative with the professionals, and the overall outcome of the treatments could be enhanced."
Dr. Lucinda Bateman, an internist who specializes in CFS and fibromyalgia and serves on the board of the American Association for Chronic Fatigue Syndrome, has worked with about 500 CFS patients over the past 15 years.
"In my clinical experience, I have found that CFS is among the most difficult conditions to improve at all, with either physical or psychological interventions." This is true in part, she says, because there is a great deal of variation among patients diagnosed with CFS, and Bateman believes that ultimately CFS may be found to involve more than one disease.
In the absence of a cure, Bateman has found that the most effective treatment for CFS combines improving symptoms with medication, helping patients retain physical conditioning when possible and using psychological and psychiatric interventions to help patients adapt to living with chronic illness.
She doesn't discount the placebo effect, however. "When you say to people, 'I believe you, I will help you manage your symptoms, I will advocate for you,' that hope and feeling of control over their disease could be considered placebo effect, but it's an important part of delivering medical care."