The cause and course of low back pain

Many people with low back pain do not present for medical care and it is important to differentiate between studies that have attempted to identify risk factors for the development of back pain per se from studies that have investigated factors that predispose individuals to present for care. While there is still controversy about the cause(s) of non-specific low back pain, the contribution of especially heavy work to an increased incidence of clinical care for low back pain has been reinforced by some recent studies and reviews. A large twin study demonstrated a small but significant increase in the risk of reporting low back pain associated with high physical demands at work , consistent with the results of prior systematic reviews . However, one study of back pain in farmers found no association between reported physical exposures and reporting of back pain, although there appeared to be links between prevalent low back pain and skin, digestive and other nonspecific disorders . Another recent twin study showed that genetic influences, not occupational factors, accounted for a large proportion of the variation in disc degeneration .

The healthy worker effect (i.e., workers tend to be ‘healthier’ since individuals who are ill or disabled are less likely to work, particularly in heavy jobs), challenges in accurately measuring exposures and the interaction of physical and psychosocial factors in the workplace all confound attempts to clearly define the relationship between workplace exposures and reporting significant low back pain problems. These challenges likely lead to an underestimation of workplace effects . Physical demands that lead to a precipitating event (such as sudden overexertion) are not well differentiated from cumulative exposures that might lead to muscle fatigue, repetitive strain or other pathways to low back pain. Despite evidence of a complex aetiology, a simplistic injury model of back pain persists, reinforced by public and private insurance and legal systems .

The paradigm of acute, sub-acute and chronic back pain is slowly being replaced by alternative, broader views of the course of back pain as a chronic, recurrent condition. A truly ‘initial’ episode of low back pain is probably rare in adults, as many children and adolescents have experienced significant low back pain episodes. In a review of epidemiological studies on adolescent low back pain, Jeffries et al. reported increasing prevalence rates that approach adult levels by age 18 . As discussed by Hayden et al. in this issue, a future direction for low back pain research is to study the condition over a longer time period, applying new methods such as life-course epidemiology approaches .

Most persons with an acute episode of low back pain recover rapidly, but many do not become entirely pain free, even if functional or work limitations resolve . A recent latent class analysis of detailed prospective data from a primary care setting, reported by Dunn and colleagues , revealed four distinct clusters, each representing a different course of low back pain – persistent but mild; recovering; severe and chronic; and fluctuating. Each cluster had a distinct pattern of functional and work disability – for example, the latter two groups were associated with the most work disability. A qualitative study by Hush and colleagues (2009) collected details from patients regarding the meaning of recovery, and represents a major advance in describing the breadth of the low back pain experience, including interaction among domains of symptom attenuation, self-defined functional activities and acceptable quality of life .

Although researchers and clinicians might measure the extent of recovery by progression of pain and functional measures, the patient’s view is often much more complex, and quite variable from person to person – suggesting that interventions need to take these perspectives into account. Longitudinal studies demonstrate that recurrent exacerbations or episodes of varying severity and duration are common. These are often managed without medical consultation – so clinicians may need to focus more on why a patient presents with a recurrence, instead of the fact that a recurrence has happened. Failure to elicit the patient’s reason for initiating the consultation may lead to iatrogenic confusion and distress, as discussed by Main et al. in this issue. Researchers need to think more about using methods to study and describe an illness that is more like a chronic disease, instead of applying approaches developed for studying acute injuries .

Early intervention for low back pain – educational approaches

Almost all episodes of acute low back pain appear to follow a course that is not altered much by traditional medical treatments. Longitudinal, population-based studies suggest that the outcomes are similar in comparable persons who seek care versus those who do not . This implies that most clinical interactions at best provide reassurance, and often lead to a process that is wasteful, and may be iatrogenic – creating a negative psychological mindset, or perhaps even leading to worse injury and illness. As an alternative, some researchers have begun to explore non-traditional (often educational) approaches, outside of the usual scope of medical treatments, intended to improve self-care and thus limit unnecessary clinical visits, worrisome diagnoses and associated disability.

The initial forays in this area investigated population-wide approaches, addressing low back pain as a public health problem, through mass media (radio, television and print advertising) and educational campaigns targeting doctors and persons with low back pain . These population-wide interventions attempted to address a key issue in low back pain, namely public perceptions and knowledge about the condition. Gross et al. (2006) found that beliefs about low back pain in two Canadian provinces were generally pessimistic and not in concordance with the current scientific evidence; these authors recommended strategies for re-educating the public . Interventions that address public perceptions and beliefs encourage new ways of looking at these problems from a societal, rather than only an individual patient level.

Furthermore, providing messages that simultaneously target the community as a whole has the potential to shift the attitudes and beliefs of the entire population towards a more evidence-based understanding of how back pain should be managed, regardless of education or socioeconomic status . Although one intervention in Australia in the late 1990s has had a long-lasting effect on both population and doctors’ low back pain beliefs , subsequent efforts in Alberta , Scotland and Norway have demonstrated improved beliefs, but failed to improve care or outcomes. However, the level of programme visibility and broad recognition by potential patients, providers and employers that was achieved in Australia was not present in these subsequent studies, suggesting that further evaluation of this approach would still be worthwhile . It is not known what effect on popular beliefs, if any, can be attributed to direct-to-consumer advertising for back pain in general. In Australia, 50% of survey respondents were aware of mass-media advertising for back pain prior to the onset of the mass-media campaign . The content of direct-to-consumer advertising for back pain is likely to vary widely. A recent study that evaluated the content of 129 newspaper articles in two provinces in Canada reported that in 24% of the articles, the primary advice regarding level of activity during an episode of back pain was to stay active, while none of the articles primarily recommended rest or avoidance of activity . A survey of low back pain information available on the Internet was less encouraging, and concluded that patients should avoid making decisions based on undirected searches for low back pain information .

Another advantage to media campaigns is the ability to reach the whole population, even those groups who are usually more difficult to reach. For example, lower educational attainment has been associated with greater conviction about physical causes of low back pain, and the value of treatment . Although there is also an association between education and beliefs about the consequences of back pain-related disability, these perceptions may reflect the reality about return to work in blue-collar versus white-collar occupations .

Providing simple evidence-based messages in the workplace, through trusted non-clinical peers, has led to improved beliefs, less demand for clinical care and improved disability outcomes . Furthermore, earlier concerns that a clinician is always required in the initial stage of a new episode of back pain, to identify whether red flags are present, appear to be unfounded. It seems that the rare patient with acute low back pain due to a serious underlying disease usually self-refers for medical evaluation and treatment, and the clinician can rapidly identify those patients who need further medical evaluation to rule out serious illness .

Early intervention for low back pain – educational approaches

Almost all episodes of acute low back pain appear to follow a course that is not altered much by traditional medical treatments. Longitudinal, population-based studies suggest that the outcomes are similar in comparable persons who seek care versus those who do not . This implies that most clinical interactions at best provide reassurance, and often lead to a process that is wasteful, and may be iatrogenic – creating a negative psychological mindset, or perhaps even leading to worse injury and illness. As an alternative, some researchers have begun to explore non-traditional (often educational) approaches, outside of the usual scope of medical treatments, intended to improve self-care and thus limit unnecessary clinical visits, worrisome diagnoses and associated disability.

The initial forays in this area investigated population-wide approaches, addressing low back pain as a public health problem, through mass media (radio, television and print advertising) and educational campaigns targeting doctors and persons with low back pain . These population-wide interventions attempted to address a key issue in low back pain, namely public perceptions and knowledge about the condition. Gross et al. (2006) found that beliefs about low back pain in two Canadian provinces were generally pessimistic and not in concordance with the current scientific evidence; these authors recommended strategies for re-educating the public . Interventions that address public perceptions and beliefs encourage new ways of looking at these problems from a societal, rather than only an individual patient level.

Furthermore, providing messages that simultaneously target the community as a whole has the potential to shift the attitudes and beliefs of the entire population towards a more evidence-based understanding of how back pain should be managed, regardless of education or socioeconomic status . Although one intervention in Australia in the late 1990s has had a long-lasting effect on both population and doctors’ low back pain beliefs , subsequent efforts in Alberta , Scotland and Norway have demonstrated improved beliefs, but failed to improve care or outcomes. However, the level of programme visibility and broad recognition by potential patients, providers and employers that was achieved in Australia was not present in these subsequent studies, suggesting that further evaluation of this approach would still be worthwhile . It is not known what effect on popular beliefs, if any, can be attributed to direct-to-consumer advertising for back pain in general. In Australia, 50% of survey respondents were aware of mass-media advertising for back pain prior to the onset of the mass-media campaign . The content of direct-to-consumer advertising for back pain is likely to vary widely. A recent study that evaluated the content of 129 newspaper articles in two provinces in Canada reported that in 24% of the articles, the primary advice regarding level of activity during an episode of back pain was to stay active, while none of the articles primarily recommended rest or avoidance of activity . A survey of low back pain information available on the Internet was less encouraging, and concluded that patients should avoid making decisions based on undirected searches for low back pain information .

Another advantage to media campaigns is the ability to reach the whole population, even those groups who are usually more difficult to reach. For example, lower educational attainment has been associated with greater conviction about physical causes of low back pain, and the value of treatment . Although there is also an association between education and beliefs about the consequences of back pain-related disability, these perceptions may reflect the reality about return to work in blue-collar versus white-collar occupations .

Providing simple evidence-based messages in the workplace, through trusted non-clinical peers, has led to improved beliefs, less demand for clinical care and improved disability outcomes . Furthermore, earlier concerns that a clinician is always required in the initial stage of a new episode of back pain, to identify whether red flags are present, appear to be unfounded. It seems that the rare patient with acute low back pain due to a serious underlying disease usually self-refers for medical evaluation and treatment, and the clinician can rapidly identify those patients who need further medical evaluation to rule out serious illness .

Acute low back pain evaluation and treatment

There are no traditional clinical approaches to acute low back pain that have large, statistically significant and consistent benefits over placebo, in rigorous trials . It has been postulated that, within large groups who have minimal benefits from a specific treatment, there are a few who have significant responses, leading to calls for recognition of important distinguishing characteristics, or risk subgroups, within the umbrella of ‘nonspecific low back pain’. Yet, so far there has not been convincing success in identifying diagnostic subgroup(s) that are likely to have different (better or worse) outcomes with a specific treatment approach . As described by Kamper et al. in this issue, research on identifying treatment-based subgroups has not progressed beyond the initial stages of hypothesis generation, and faces considerable methodologic hurdles .

Active placebos are interventions without known specific effects, but have the full confidence of patients that they can be effective – these can include sham acupuncture, sugar pills or light massage. Recently, trials with an active placebo have demonstrated significant effects compared with more passive placebo interventions, highlighting the potential for nonspecific effects of low back pain treatment . These observations have generated considerable interest in maximising the positive impact of patient expectations, beliefs and attitudes on outcomes in back pain management .

A related issue is that current low back-pain guidelines suggest what not to do, but do not offer advice on how to effectively dissuade patients from useless therapy. A Dutch study plans to educate primary care physicians on how to address patients’ back pain beliefs and expectations to improve the quality of care and outcomes . Recent guidelines offer specific suggestions on ways to address work-related concerns with low back pain, but research on how to best integrate these efforts into busy primary care practices has not yet emerged . In their article on addressing patient beliefs and expectations in the consultation, Main et al. have outlined a plan for tackling these issues.