Chronic Pain Is Not a Disease
Mistakes the Institute of Medicine made in saying pain is a disease.
Posted May 27, 2018
Is chronic pain a disease? August groups, such as the American Academy of Pain Medicine (AAPM) and the Institute of Medicine (IOM) (now the National Academies of Sciences, Engineering, and Medicine) have proposed that it is. Indeed, the IOM stated that chronic pain, “…is a distinct pathology causing changes in the nervous system…” There are several problems with this line of thinking that have serious implications not only for care of the chronic pain patient but also for the care of all patients. Let’s see how.
Although research does demonstrate objective functional and structural changes of brain reorganization in chronic pain, these changes are due to the severe pain itself as well as the distress, depression, and multiple other dimensions of suffering that accompany chronic pain. That is, the symptoms and attendant suffering cause the brain changes rather than brain changes causing the symptoms.1-4 The latter would be the case if there was an underlying, causative brain disease.
While pain may be a symptom of a disease, such as headache in brain cancer or chest pain in a heart attack, the term “disease” requires an underlying explanatory abnormality identifiable by laboratory and other investigative procedures. When we find no underlying disease explanation for a symptom, say, pain or fatigue or loose stools, the descriptive term “unexplained symptoms” is presently the best we can do in medicine. Despite yeoman efforts by researchers over many decades to find objective changes of an underlying, causative disease, they have been unable to explain chronic pain or many other syndromes, such as fibromyalgia or chronic fatigue or irritable bowel syndrome, on a disease basis.
Unexplained symptoms are common. Over three-fourths of all physical symptoms have no explanatory disease.5 Indeed, who has not had some symptom without a disease, such as a minor headache or lightheadedness? The spectrum of unexplained symptoms extends from minor, for which we don’t even seek care or are easily reassured if we do, to very severe and disabling. Chronic pain is at the most severe end of the spectrum.6
The minor to moderate unexplained symptoms present little difficulty in medicine. While they may relate to stress, an associated mental disorder is no more common than in the general population. Extensive research, however, tells us that the more persistent, the greater the number, and the more severe the unexplained symptoms, the more likely is an associated mental disorder, typically depression.6 In a study my group conducted in mostly severe chronic pain patients, 94% had depression.7 This and much other research demonstrate that severe and disabling chronic pain is a symptom associated with serious psychosocial distress, often a major mental disorder such as clinical depression. Indeed, some research indicates that depression itself accounts for the secondary brain changes described above. Chronic pain is an uncommon type of unexplained symptoms but still prevalent in physicians’ offices, as much as 5-10% of their patients.
Why did this mistake happen—calling a symptom a disease where there is no antecedent, underlying disease causing the symptoms? There’s a very simple explanation. Medicine’s guiding biomedical model focuses only on disease. That’s what everyone, including the IOM and AAPM people, was taught. It completely excludes the psychological and social dimensions of patients—the human dimension. These features also are what defines chronic pain: psychosocial and mental distress. By ignoring the psychosocial aspects of chronic pain, the disease-only model cannot explain the problem without the contorted proposition that a symptom represents a disease even though there is no antecedent, causative abnormality. Nor does the biomedical, disease-only model accommodate treatment for the psychosocial and mental health problems so prominent in chronic pain. This has resulted in using disease-based treatments, like opioids, and ignoring treating psychosocial issues like depression.
Not at all accepted in medicine, the alternative biopsychosocial (BPS) model integrates the biological (disease) elements into their psychological/mental and social context.8 The BPS model applies the term ‘illness’ to the universally present psychosocial issues that reflect the impact on patients’ lives of the symptoms for which they sought care—whether or not a disease is present. Thus, most who seek care have an illness, the severity based on the degree of psychosocial distress. Only the BPS model accommodates this distinction. Therefore, chronic pain is an illness with severe psychosocial distress, not a disease.
Using the term disease to explain chronic pain reflects a subconscious bias favoring disease-only medicine. While many in medicine, including the IOM and AAPM, acknowledge that psychosocial issues are important, medicine’s actual behavior belies this. You will agree, I’m sure when you learn the following fact. Over the 7-8 years of medical school and residency training, only 2% of total training time addresses the psychosocial and mental dimensions, including chronic pain. This means that the thousands of hours making up the remaining 98% of teaching time are devoted only to bona fide diseases. This may explain why the IOM and AAPM force-fit the term disease. They unwittingly follow the disease-only, biomedical model and have no other way to explain the problem. Writ large, because the IOM and AAPM simply are bellwethers, this is the problem of modern medicine.
Therefore, this post is not simply splitting hairs over choice of words—illness or disease. Rather, I suggest that the confusion of the IOM and AAPM on terminology reflects a fundamental misunderstanding of how to approach patients of all types. The very common and unfortunate chronic pain patient simply makes the problem manifest because the governing model of medicine cannot accommodate them. If medicine can address this fundamental fault in its conceptual infrastructure, they will automatically know how to better handle the chronic pain patient—and everyone else.
Here’s how we will know when this change occurs. Medical student and resident training will produce graduates as competent in the psychosocial and mental as in the disease dimensions.
1. Rodriguez-Raecke R, Niemeier A, Ihle K, Ruether W, May A. Brain gray matter decrease in chronic pain is the consequence and not the cause of pain. J Neurosci 2009;29:13746-50.
2. Apkarian AV, Hashmi JA, Baliki MN. Pain and the brain: specificity and plasticity of the brain in clinical chronic pain. Pain 2011;152:S49-64.
3. Kuner R, Flor H. Structural plasticity and reorganisation in chronic pain. Nat Rev Neurosci 2017;18:113.
4. Baliki MN, Schnitzer TJ, Bauer WR, Apkarian AV. Brain morphological signatures for chronic pain. PLoS One 2011;6:e26010.
5. Kroenke K, Mangelsdorff AD. Common symptoms in ambulatory care: incidence, evaluation, therapy, and outcome. Am J Med 1989;86:262-6.
6. Smith RC, Dwamena FC. Classification and diagnosis of patients with medically unexplained symptoms. J Gen Intern Med 2007;22:685-91. PMCID: 1852906.
7. Smith R, Gardiner J, Luo Z, Rost K. The diagnostic accuracy of predicting somatization from patients' ICD-9 diagnoses. Psychosom Med 2008;71:366-71; NIHMSID: NIHMS88597; PMCID: PMC2669490.
8. Smith R, Fortin AH, VI, Dwamena F, Frankel R. An Evidence-based Patient-Centered Method Makes the Biopsychosocial Model Scientific. Patient Educ Couns 2013;90:265-70.