The Expensive Logical Fallacy in Pain Management

Each weekday in pain clinics across the country, a particular clinical practice pattern occurs that costs the healthcare system tens of millions of dollars on an annual basis (Gaskin & Richard, 2012) and it’s the result of a logical fallacy that both provider and patient alike commit.

Suppose a patient with back or neck pain presents to a pain clinic. Presumably, the patient has had such pain for a number of weeks or even months, as the point of entry into the healthcare system upon a new onset of back or neck pain isn’t a pain clinic itself, but rather a primary care clinic or urgent care. So, assuming that the initial provider followed the typical guidelines for acute back or neck pain, the patient would have been counseled to remain active, prescribed an anti-inflammatory, and possibly would have been referred to physical therapy or chiropractic care or both. Most patients with an acute episode of back or neck pain get better with time and/or these therapies. However, perhaps one in five don’t. These patients thus tend to get referred to a pain clinic.

It’s at this point too that scans tend to get ordered. It may occur just prior to the referral or upon evaluation at the pain clinic, but either way patients tend at this point to undergo a CT or MRI scan. In other words, a search begins for some form of injury -- tissue damage or some other orthopedic abnormality -- that might be causing the pain.

In the majority of cases, the results of the scans fail to correspond with the pain that the patient reports. If we wanted to be really academic about it, we’d have to say that in most cases of back or neck pain the MRI or CT results fail to explain why the patient has pain. A large minority of cases will have no abnormal findings at all. Another large minority of cases will have findings, but the findings will be in the wrong place or of the wrong kind to cause the pain that the patients report. In either type of case, we call such pain “non-specific”. Adding both types together, the sum total of people who present with non-specific back or neck pain make up the majority of all people with back or neck pain (Krismer & van Tulder, 2007).

Now, in pain clinics across the country, a funny thing happens. These common non-specific findings don’t lead providers to look elsewhere for the source of the pain (such as the overall state of the patient’s nervous system at the time of the strain to the back or neck). Instead, the focus remains on identifying some potential tissue-based injury or abnormality. In interventional pain clinics and surgery clinics, it typically gets referred to as the "pain generator” and the search for it usually occurs in the spine.

The belief is that back or neck pain must be due to some form of tissue damage that is orthopedic in nature. This belief justifies the continued search even when the original scans don’t identify it. Patients subsequently undergo epidural steroid injections for diagnostic purposes, in order to identify the pain generator. Patients might also undergo medial branch blocks or discography or both. Based on the results of these diagnostic procedures, patients might undergo still further therapies, such as neuroablation or spine surgery, even if the original scan suggests that the pain is non-specific.

The results of these diagnostic procedures are thus valued more than the results of the original scans when it comes to making decisions about what therapies to pursue, even in cases where the two types of diagnostic information conflict. The reason is the belief that back or neck pain must be orthopedic in nature. It must be due to some form of tissue damage or abnormality in the spine.

The value of what these further tests might find corresponds in our society to the value that we place on having an orthopedic-based reason for back or neck pain. In effect, such a reason legitimizes the pain. If we can find an orthopedic abnormality, we know, then, that the pain is real pain. This inference is often the reason for continuing to engage in further testing and in fact further interventional procedures and spinal surgeries, even when the initial scans find that the back or neck pain is non-specific. For if a diagnostic injection or discography can find some evidence for an abnormality, then an interventional or surgical procedure can seemingly be justified and correspondingly both provider and patient alike can rest assured that the patient has real pain – that is to say, spinal pain.

This argument rests on the belief that all back or neck pain – real back or neck pain, if you will, is due to some form of orthopedic-based tissue damage, usually considered to be in the spine.

This belief, however, is the result of committing to a logical fallacy. It goes something like the following:

• Orthopedic-based tissue damage, typically considered to be in the spine, causes back or neck pain.
• A patient has back or neck pain.
• Therefore, the patient’s back or neck pain is due to some form of orthopedic-based tissue damage, likely in the spine.

This type of reasoning is called ‘affirming the consequent’ and it’s fallacious.

It’s a fallacy because not all back or neck pain is caused by orthopedic-based tissue damage, whether in the spine or not. When we engage in such fallacious reasoning, we neglect the fact that there are other ways in which we come to have pain.

Think, for the moment, of the different kinds of common pain disorders with which patients tend to present: tension headache, migraine headache, temporomandibular joint disorder, fibromyalgia, irritable bowel syndrome and other idiopathic abdominal pains, complex regional pain syndrome, phantom limb pain, non-cardiac chest pain. None of these conditions have any form of tissue damage as their primary cause. Instead, it's generally accepted that the primary cause of these conditions lie in an intact nervous system, albeit one that has become excessively sensitive so that the threshold for stimuli to cause pain has been lowered to the point that various forms of stimuli beyond tactile stimuli (e.g., stressful stimuli) have the capacity to cause pain.

When we don’t neglect the fact that pain can be caused in this manner, in addition to tissue damage, we might then entertain the hypothesis that non-specific back or neck pain is real pain that has no corresponding tissue damage, just as the initial scans so often inform us that it is. In other words, what if non-specific back or neck pain is more akin to a tension headache than a bone fracture?

Basic pain science of the last forty years would support our hypothesis too (see, for example, Johnston, et al., 2008; Latremoliere & Wolf, 2009; Treede, 1995; Wolf, 2011).

From this perspective then, the insistent belief that all back or neck pain, if it’s to be real pain, must have an orthopedic-based cause, even after an initial scan tells us otherwise, is not only fallacious, but leads to over-testing and subsequently overtreatment (Brownlee, 2008; Welch, Schwartz, & Woloshin, 2012). The expense of this over-testing and overtreatment is hard to underestimate.

References

Brownlee, S. (2008). Overtreated: Why too much medicine is making us sicker and poorer. New York: Bloomsbury.

Gaskin, D. J., & Richard, P. (2012). The economic costs of pain in United States. Journal of Pain, 13(8), 715-724.

Johnston, V., Jimmieson, N. L., Jull, G., & Souvlis, T. (2008). Quantitative sensory measures distinguish office workers with varying levels of neck pain and disability. Pain, 137(2), 257-265.

Krismer, M. & van Tulder, M. (2007). Low back pain (non-specific). Best Practice & Research Clinical Rheumatology, 21(1), 77-91.

Latremoliere, A. & Wolf, C. J. (2009). Central sensitization: A generator of pain hypersensitivity by central neural plasticity. Journal of Pain, 10(9), 895-296. doi: 10.1016/j.pain.2009.06.012

Treede, R. (1995). Peripheral acute pain mechanisms. Annals of Medicine, 27(2), 213-216. doi: 10.3109/07853899509031961

Welch, H. G., Schwartz, L. M., & Woloshin, S. (2012). Over-diagnosed: Making people sick in the pursuit of health. Boston, MA: Beacon Press.

Wolf, C. J. (2011). Central sensitization: Implication for the diagnosis and treatment of pain. Pain, 152(Suppl 3), S2-15. doi: 10.1016/j.pain.2010.09.030