The Burden of Chronic Pain: Can We Predict Where It Is Most Likely to Fall?

When most people think of serious illnesses, they generally have in mind those that can destroy the body, such as heart disease, cancer, and diabetes. A recent study that examined the state of health in the US demonstrates that while the number of years of life lost to illness is obviously of great importance, it is not the only way we should view the relative impact of diseases on national health.¹

The study looks at the overall health burden described as disability-adjusted life years that takes into account both the effect of potentially fatal diseases by measuring years lost to premature mortality and the effect of more chronic disorders measured by years living with a disability. Not surprisingly, the diseases leading the category of years lost to premature mortality are ischemic heart disease, lung cancer, stroke, and chronic obstructive pulmonary disease. In contrast, the diseases at the head of the category of years living with a disability are quite different: low back pain, MDD, other musculoskeletal disorders, neck pain, and anxiety disorders. Probably most laypeople and even many health care professionals, apart from those who suffer from these disorders or those who specialize in treating them, might be surprised at the significant contribution of these illnesses to the national health burden.

Although the study appears to view these physical and mental disorders in the years-living-with-a-disability category as being independent of each other, in reality there is a great deal of overlap between them. It is well known that there is significant comorbidity between chronic pain and depressive and anxiety disorders. Pain can be a presenting symptom of these disorders, and the experience of chronic pain can also lead to their development. The serotonin-norepinephrine reuptake inhibitors are efficacious not only for the management of depressive and anxiety disorders but also as analgesics for a variety of forms of chronic pain, including low back pain.

When looking at these top 5 years-living-with-a-disability disease categories, we may actually be seeing, at least in some patients, different presentations of similar disease processes. This also indicates the importance of addressing both physical pain and psychological factors together rather than as separate, unrelated issues.

Another recent study highlights the importance of addressing these issues together. Campbell and colleagues² followed up 488 patients who had visited their primary care providers for low back pain and sought to determine whether there were any factors that predicted continuing significant pain, indicated by substantial pain and related disability after 6 months and 5 years. The researchers examined 32 possible prognostic factors that they grouped under 4 general categories: demographic, physical, psychological, and occupational.

Two of these factors best predicted ongoing pain at follow-up. The first was the level of the pain when the patient initially visited the primary care physician; the more intense the pain, the more likely it was to become chronic. The second is perhaps more interesting and one that might have the best chance of being affected: chronic pain was more likely to occur in those who believed their pain would persist.

We might expect a greater initial level of pain to worsen outcome, because this would suggest that the pain might be more difficult to ameliorate. Determination of intensity is an important part of pain assessment, and it helps health care professionals make treatment decisions.

However, patients are much less likely to be asked whether they believe that the pain will be significantly alleviated, and this study shows that they need to be asked. This factor appears to be especially amenable to cognitive-behavioral therapy, which would have a significant effect on outcome and would eliminate the possible and, at times, irreversible adverse effects associated with common treatments for low back pain such as medications, epidural corticosteroid injections, and surgery.

We are well aware of risk factors that make many diseases more likely to occur and increase their associated morbidity and mortality. Smoking heightens the risk of a variety of cancers and cardiovascular and pulmonary diseases. Obesity can also affect these conditions, and it increases the risk of type 2 diabetes mellitus. Although we cannot eliminate these diseases, we know that by addressing these problems and behaviors we can reduce their occurrence.

When it comes to the prevention of chronic pain and especially chronic low back pain, there is less clarity about which behaviors and health issues we should address. In fact, the health burden study found that of the 5 greatest risk factors it identified for disability-related problems-dietary risks, tobacco smoking, high body mass index, hypertension, and high fasting plasma glucose-only body mass index is associated with the development or persistence of low back pain or other musculoskeletal disorders.

The new study on chronic low back pain is not the final answer to why this problem develops. Other factors, most notably a poor level of functioning at the time of initial presentation, may be key predictors of failure to improve, but the study results certainly support the importance of recognizing and addressing the psychological factors that appear to play an crucial role in the transition from acute to chronic pain.

Greater utilization of early psychological interventions in cases of low back pain and other types of pain that may become chronic might help us reduce some of the associated disease burden. Unfortunately, “The main sources of diminished function and quality of life . . . may receive less attention in policy and research than they warrant in terms of their overall contribution to the burden of disease.”³

References:

1. US Burden of Disease Collaborators. The state of US health, 1990-2010: burden of diseases, injuries, and risk factors. JAMA. 2013;310:591-608.

2. Campbell P, Foster NE, Thomas E, et al. Prognostic indicators of low back pain in primary care: five-year prospective study. J Pain. 2013;14:873-883.

3. Fineburg HV. The state of health in the United States. JAMA. 2013;310:585-586.