Few will argue that the concept of acute low back pain (LBP) resolving in 4 to 6 weeks for 75% to 90% of sufferers is totally inaccurate.^1,2,3,4 This unrealistic, overly optimistic picture, in the past, had led to false confidence and poor outcomes, because a passive management philosophy involving symptomatic approaches (bed rest and medication) or a nonmanagement approach of leaving it alone to let “nature run its course” simply did not pan out. There are two problems with this perspective. First, the view that most acute episodes resolve quickly and completely is disputed by a number of studies of primary care patients.^5,6,7 Second, there has been a continuous growing body of evidence that it is much more cost-effective to prevent chronicity in those at risk for it rather than waiting to treat only those in whom it becomes fully apparent.

Von Korff et al demonstrated in a nonoccupational setting that after 1 month only 30% of neck pain and LBP patients achieved pain-free status, and after 1 year 50% still reported recurrent or persistent pain.⁷ Most recent studies show that the majority of acute episodes tend to improve rapidly, although not completely, and then run an intermittent chronic course with less severe “flare-ups.” The original episode frequently lasts for as long as 3 months—not 4 to 6 weeks—before it can even be said to have remitted.^6,8 The “flare-ups,” which are predictable in the majority of cases 1 year later, are mild to moderately activity-limiting and painful and lead to general dissatisfaction with the symptoms.^6,7,8 Thus, back problems typically run recurrent or chronic remitting courses with occasional acute self-limiting episodes.

Even though only a small percentage (7%) of individuals with acute LBP have chronic unremitting pain and disability, this group accounts for the majority of the costs.^9,10 More specifically, 7.4% of patients account for approximately 75% of all the costs and 85% of the disability days.^10,11 Thus, identifying potential risk factors for acute pain becoming chronic has become the “holy grail” of LBP research.^12,13

The prevalence of acute LBP becoming chronic has remained similar as noted in more recent studies.^14,15 In a 2012 meta-analysis that included 33 cohorts consisting of 11,166 participants, the difference between the acute LBP sufferers resolving and those becoming chronic was distinguishable after 6 weeks of tracking pain and disability levels, with the majority improving markedly in the first 6 weeks. In a review of a book chapter entitled “From Acute to Chronic Back Pain: Risk Factors, Mechanisms and Clinical Implications,” published in the British Journal of Anaesthesia, the following was reported: “A triumvirate can be defined as ‘any association of three in office or authority’: the political alliance of Gaius Julius Caesar, Marcus Licinius Crassus, and Gnaeus Pompeius Magnus being perhaps the most famous.”¹⁶ They go on to make the analogy of the biopsychosocial (BPS) model as being perhaps the most famous in pain medicine, stating that few would argue that these three components are inseparable when it comes to discussing the basis of modern pain management and its endorsement by the Faculty of Pain Medicine, the British Pain Society, and the International Association for the Study of Pain. Indeed, few would challenge this concept, because the evidence supporting the transition of acute to chronic pain has grown significantly since this model was first proposed in the mid- to late 1970s.^17,18

In support of the BPS model, modifications were proposed 25 years later by Borrel-Carrio et al, who recommended that three clarifications be considered: “1) the relationship between mental and physical aspects of health is complex—subjective experience depends on but is not reducible to laws of physiology; 2) models of circular causality must be tempered by linear approximations when considering treatment options; and 3) promoting a more participatory clinician-patient relationship is in keeping with current Western cultural tendencies, but may not be universally accepted.”¹⁹ Further, they proposed the following “pillars” for the BPS-oriented clinical practice: “(1) self-awareness; (2) active cultivation of trust; (3) an emotional style characterized by empathic curiosity; (4) self-calibration as a way to reduce bias; (5) educating the emotions to assist with diagnosis and forming therapeutic relationships; (6) using informed intuition; and (7) communicating clinical evidence to foster dialogue, not just the mechanical application of protocol.”

Assessment of spine patients has traditionally focused on finding the physical cause of the pain. Imaging techniques have figured prominently in this endeavor. Unfortunately, this has been an inefficient use of resources because of the poor specificity of this expensive
screening approach.^{20,21,22,23,24,25,26} Clinical scientists have summarized that the following measurable outcomes are representative criteria of patient recovery: pain, function (disability), well-being, work status, and satisfaction.^13,27 According to Pinchus et al, the risk of long-term LBP-related activity limitations (disability) and work loss (participation) arises from four main sources that interact with each other (Table 7.1).²⁸ Individual factors have been referred to as psychosocial “yellow flags.”²⁹ “Yellow flags” are analogous to the concept of “red flags” in that they both influence the management and prognosis of the patient. Whereas “red flags” are indications for biomedical laboratory or imaging investigations and possibly specialist referral, “yellow flags” are indications for investigating the cognitive, affective, and behavioral aspects of LBP.

Most yellow flags pertain to individual or work-related factors, yet the effect the treatment provider has on outcome is also important.^30,31 Reis et al evaluated both the patients’ and clinicians’ perceptions of worry, coping, limitations, expectation of pain relief, and pain interference. When evaluated individually, both patients’ and clinicians’ perceptions were found to predict outcome at 2, 4, 8, and 12 months. Because many patient characteristics are stable and thus nonresponsive to change (such as premorbidity, high levels of depression, and catastrophizing), other risk factors that may be amenable to change such as patients’ or clinicians’ perceptions and expectations should receive greater attention.

The influence of perception on outcome is highlighted by Kalauokalani et al’s study of 135 patients with chronic LBP who were allocated randomly to receive either massage or acupuncture.³² Patient expectations regarding the potential helpfulness of each treatment correlated more than other variables with subsequent functional outcomes as assessed at 10 weeks using the modified Roland score.

Similarly, in a systematic review of the literature, 23 studies covering 18 different cohorts identified 16 psychosocial factors in three domains: social and socio-occupational, psychological and cognitive, and behavioral.³³ They reported that depression, psychological distress, passive coping strategies, and fear-avoidance beliefs were sometimes found to be independently linked with poor outcome, whereas most social and socio-occupational factors were not. Because of biomedical confounding factors, they reported the predictive ability of a patient’s self-perceived general health at baseline was difficult to interpret. Again, the patient’s or health care provider’s initial perceived risk of persistent LBP was, reportedly, most consistently linked with the actual outcome.

Linton reviewed psychological risk factors in back and neck pain with the objective to summarize current knowledge concerning the role psychological factors play in the cause and development of back and neck pain.⁴¹ In doing so, 913 potentially relevant articles were located, with 37 studies consisting of only those with prospective designs to ensure quality. The review procedure resulted in the reporting of the main predictor variables and the outcome criteria. If a statistically significant relation was determined, a plus (+) or minus (−) was used to indicate a positive or negative association, respectively. If no statistically significant relationship was found, a zero (0) was used. The conclusions include a grading system similar to that used for meta-analysis review and guidelines preparation.⁸³ These grades include the following:

Level A: Evidence is supported by two or more good-quality prospective studies

Level B: Evidence is supported by at least one good-quality prospective study

Level C: Inconclusive data exist

Level D: No studies were found to meet the criteria utilized

Table 7.4 offers a summary of the conclusions drawn from this review of prospective studies.

What follows is a list of those specific risk factors—called “yellow flags”—for acute LBP becoming chronic. These have been identified primarily from an assortment of prospective longitudinal studies. Few cross-sectional studies were used as sources for the “yellow flags.” They are divided into those related to
symptoms, examination, and psychosocial, functional, and work-related factors (Table 7.5). “Yellow flags” are primarily subjective and have a significant psychosocial predominance. Whereas “red flags” such as cauda equina syndrome, cancer, fracture, and infection require urgent attention, further testing, and possibly specialist referral, “yellow flags” only require a shift in the focus of care. These risk factors have been reported to predict future chronic pain or disability in the United States,^5,84,85,86 New Zealand,^29,41,43 and England.^43,87