Epidemiology and Risk Factors

Studies regarding the epidemiology of low back pain are highly variable. This is not surprising—it is a condition that is highly specific to each individual patient. Survey studies are difficult because one patient’s perception of pain may be quite different than that of another. The incidence of developing a new episode of back pain has been estimated as low as 4% and as high as 93%.^6–9 On the basis of larger longitudinal studies, this incidence has been estimated to be much lower, between 3% and 5% for episodes where patients sought medical attention. The incidence of back pain that did not require professional medical care was much higher, at 30%.⁷ Prevalence is difficult to study due to variance among study populations and the different factors that may affect the development of low back pain. Studies estimate that 15% to 20% of adults experience memorable low back pain within 1 year and up to 80% experience such pain over a lifetime.^10–13

In terms of age, back problems do not necessarily occur more frequently during the third to fifth decades. When they do, however, they are certainly more often related to claimed disability during this period. These are the prime working years, where low back pain leads to the greatest disability and days off work. Interestingly, the symptoms of low back pain do not become worse with age-related degeneration of intervertebral discs.^1,14–17 Back pain in the elderly is thought to be one of the most important factors to affect the individual state of health.¹⁸ Similar to younger adults, the prevalence of back pain in patients older than 65 years of age is 13% to 49%,¹⁹ but this pain seems to be more episodic and intermittent with a lesser occurrence of chronic pain.²⁰ Despite the relatively high prevalence of abnormal curvature of the spine in adolescents, the chance of these children presenting with low back pain is quite low. Some studies suggest that the peak age for development of back pain in children is 13 to 14 years and that beyond this age, the risk factors for developing back pain in adults also apply in children.^21–23

Risk factors for the development of low back pain are demographic, physical, socioeconomic, psychological, and occupational factors. Many studies of these risk factors are small and include only self-reports of the variables. A review by Hildebrandt discusses 55 personal factors and 24 occupational factors that have been linked to low back pain.²⁴ Many studies have looked at the relationship between socioeconomic status and level of education and the development of back pain. The association seems to be not so much with the incidence of pain but with the ability to adjust to pain. The incidence of disability from back pain appears to be 22 to 25 times higher in patients with less than 7 years of education compared with those with college degrees.²⁵

Observations Regarding Low Back Pain and Disability

First, it is important to differentiate between pain and disability. Both are related in that they are generally subjectively relayed by the patient and are not viewed the same in any two patients. There is no objective measure for either of these disorders. Disability is related to the patient’s perceptions and attitudes about pain^26,27 and may be based on avoidance based on previous painful experiences.^1,28,29 Many people live with low back pain, and few patients view this condition as a disability.

It is also useful to discuss the difference between acute and chronic pain. Acute pain often bears a close relationship to an inciting event and may be thought to stem directly from tissue injury. Chronic pain, on the other hand, is often a behavioral adaptation of an individual who may or may not have had an initial injury. This bears very little relationship to physical injury and is very difficult to treat by medical and surgical means. The failed back syndrome is indeed closely related to this concept. Chronic pain becomes a syndrome of emotional distress, depression, and disease conviction.¹ If these patients are taken to surgery under the misconception that their pain is actually related to tissue injury, they are virtually never cured and are often made worse. Surgery in these patients also plays into the “sick role” and gives them further reason to take time off work and to claim that they are disabled. These patients often clog pain clinics and spine clinics and place a heavy burden on the health-care system.

Despite low back pain and sciatica taking center stage in many medical circles today, there is no evidence that the biology of the problem has changed at all over the years. Back pain is the same as it always has been. It is low back disability that is a new concept. Ninety percent of patients with low back pain become better within 6 weeks in spite of technologically advanced medical and surgical care, or interestingly, no care at all.^1,15,30,31 This is likely a product of the explosion in the size and complexity of the health-care systems of Western countries and individuals’ perceptions that the abilities of modern health care should be able to end pain. Physicians bear some responsibility in this regard because it is they who certify patients with pain to be excused from work, thereby feeding into the concept of low back disability.

Perhaps the most referenced expert to publish on low back pain and disability is Gordon Waddell. In his book The Back Pain Revolution,³² he discusses his time spent in Oman. At the time of his writing, Oman was an emerging, primarily developing country. In the mid-1980s, new oil money soon brought modern medical treatments to this country. At the time, patients with back pain flooded into the newly established clinics seeking treatment for their pain. These patients had very similar problems with similar etiology to patients in developed Western countries. The interesting part is that nearly none of them were off work or “disabled” as a result of their pain. Waddell’s observation was that the patients who were able to escape the confines of their country to have “modern” medical procedures in other countries became disabled after surgery at a much higher rate than those who did not have access to modern medical care. This is another illustration that suggests that low back pain is nothing new but that low back disability is largely a product of modern Western medicine.

Breakdown of the Disease Model of Illness

As mentioned earlier, modern medicine now largely depends on the disease model of illness. This model, which has been adapted over the years from roots in the 16th and 17th centuries, follows a progression from physical signs and symptoms, to diagnosis, to treatment, to cure. This depends directly on the fact the “disease” (pain, in this case) comes from physical pathology and excludes factors such as psychogenic and social issues. As this model breaks down, one can easily see that a prospective therapy does not lead to cure unless there is a true link between a presumed tissue injury and the physical signs of pain. This is probably not the case in the vast majority of patients with low back disability.

Chronic low back pain probably is better considered in the context of a different disease model, the biopsychosocial model. This model stresses the integration of the mind-body continuum, which has been proposed by philosophers since before science was born. This suggests that it is not only the responsibility of the physician to treat the body but also to assist the patient in adjusting to their illness and coping with it mentally. The gate theory of pain and experience with psychosurgery both support the assertion that pain perception requires both sensory and emotional components and can be modified by mental, emotional, or sensory mechanisms.³³

These concepts are very solidly related to the diagnosis and treatment of low back pain. As it turns out, many patients are not satisfied with an office visit without the establishment of a diagnosis based on real pathology. Disc disease has become so popular and common, and patients may be given the nominal diagnosis of disc prolapse without any signs of nerve root compression or radiographic evidence. It is not long until this nominal diagnosis is confused with real disease pathology, and the patient receives the label of discogenic low back pain. These patients may eventually end up being treated with surgery and then bouncing from clinic to clinic when this operation fails. Clinics are clogged with these patients, making it difficult to care for patients with real pathology. Making matters worse, patients often go from clinic to clinic until a diagnosis is made, leaving an incentive for physicians to make nominal diagnoses or risk losing patients. Indeed, a large study of the indications for spinal surgery in the mid-1980s showed that surgical decision making was often driven by duration and severity of pain and disability, patients’ illness behavior, and failure of conservative treatment.³⁴ As might be expected, the success rate for surgical treatment based on a nominal diagnosis is at best 30% to 40%. Interestingly, nearly every study in the past 50 years has shown that the presence of a psychiatric disease as an extremely poor predictor for good surgical outcome.^1,35–43 Thus, the responsible surgeon must use the history and physical examination to tease out signs of psychiatric imbalance and consider this carefully prior to proceeding with surgery.

Work-Related Issues

Since complaints of low back pain hit a peak during the working years, it is essential to discuss this process as it relates to time off work. First, this problem is most prominent in the group of patients with chronic low back pain. In a study by Volinn et al., 2% of workers eligible for industrial insurance filed a claim for back pain in 1 year. Of those, 12% were off work for 90 days or more, consuming more than 88% of the wage and medical compensation paid by insurance.⁴⁴ This same study found that the complaints of back sprain and pain were closely related to workplace dissatisfaction and monotonous job tasks. The medical costs largely involved surgery and hospital stays for “medical back problems.” One study of Medicare patients found that 71% of these “medical back” hospitalizations were inappropriate.⁴⁵ In a review of low back pain and health care utilization, Volinn et al. suggest that the level of both cognitive and economic investment in low back pain drives therapy.⁴⁶ Only when further knowledge and education of outcomes regarding the treatment of low back pain become available, and third party payers invoke more stringent guidelines for what will and will not be reimbursed, will the trends in surgical and medical management change.

The historical and still common practice of “therapeutic rest” appears to be based on multiple fallacies. First, pain is related to tissue injury and inflammation in the spine, and rest will help reverse or alleviate this process. Second, if the pain does not come from inflammation of the spine, it must come from degenerative disc disease, and the only way to allow the disc to heal is with rest. By the disease model of illness, this seems to be a logical progression, but as previously discussed, the disease model of illness does not translate well into the world of low back pain. Considering the biopsychosocial model and assuming that chronic pain is not due to significant injury to or instability of the spine, this treatment does not make sense at all. It aims to treat a process that likely is not active and fails to treat and may actually worsen the psychological aspects of the disease and help the patients fit into the sick role.

Indeed, there is no good evidence in the literature that rest improves low back pain or even sciatica. This is a somewhat difficult area to study without a high degree of bias, and as one might expect, the major studies are methodologically flawed. Even in the majority of these studies, it was found that shorter periods of rest were more beneficial (or less harmful) than longer periods.¹ Along with these findings, there have been no studies to suggest that activity worsens pain or tissue injury in the absence of a known lesion. Many of these patients continue to complain of the same degree of pain whether or not they are performing their daily activities. It is clear that prolonged rest is harmful to both body (bone demineralization,⁴⁷ cardiac deconditioning,^48,49 and loss of muscle strength) and mind (depression and anhedonia).^50,51 The physician who prescribes to the patients with low back pain has clearly done them no favors.

Similarly to the notion that an individual’s back pain can affect his or her job, the characteristics of the job can affect the back pain. A study by Boos et al. showed that the characteristics of one’s job (listlessness, job satisfaction, working in shifts) were more likely than MRI to identify disc abnormalities and to predict whether one would seek medical treatment.⁵² Similarly, these factors also are useful in predicting which patients are likely not to be working at follow-up.

All of these issues have opened up much controversy and academic thought to litigation and workers compensation in the current health-care system. In the present system, compensation is largely tied to the presence of physical examination findings and imaging confirmation of disc herniation. Some studies suggest that psychological factors may also be tied in to the selection of patients for workers compensation benefits and that patients with emotional instability may be less likely to receive compensation.⁵³ There is decent evidence to suggest that patients who receive time-limited workers compensation as opposed to long-term disability are more likely to return to work and have a good outcome.⁵⁴ Another study by Atlas et al. also revealed that patients who were receiving workers compensation at baseline prior to their low back disability were more likely to be receiving long-term disability benefits than those who were not (27% vs. 7%), and they were also slightly less likely to be working at 4-year follow-up.⁵⁵ This correlates with the earlier assertion that time off work and prolonged compensation benefits allow patients to more easily adopt the sick role.

Summary

It is clear that low back pain and disability are epidemic in virtually all parts of the industrialized world today. The main differences among countries are the way back pain is viewed and treated. In Western society, the expectation from patients is generally that they will benefit from surgery, and if not, rest and time off work are the best treatment options. It is also clear that low back pain does not fit into the classic treatment paradigm of the disease model of illness. In this case, the biopsychosocial factors may be more at work than actual physical tissue injury. These patients place a large burden on the medical system and often bounce from clinic to clinic until they find a physician who will treat them. They then are often the victims of unindicated surgery and fall into the category of failed back syndrome. It is clear that only when surgical candidates are chosen carefully and selectively, surgical therapy can lead to the best and most efficient outcomes, with early return to work and relief of symptoms. It is also apparent that the traditional method of therapeutic rest is inadequate and may actually lead to a decline in the patient’s functional status. The exact roles of workers compensation and disability are still somewhat unclear, but it is likely that these only reinforce sick behavior.

We advocate a multidisciplinary approach in the spine clinic that involves spine surgeons, occupational therapists, physical therapists, mental health professionals, sports medicine specialists, and social workers. Using this method, appropriate surgical candidates can be selected, and the remainder of patients can be funneled into a low back training program. This program allows them to become empowered and take control and initiative in their disease and avoids their “shopping” around to other clinics. Only by addressing all of these issues can care for patients with low back pain be adequate and efficient.