Friday, April 23, 2010

Who Develops Persistent Disabling Low Back Pain?

Back PainThe severity of pain itself at the onset of nonspecific low back pain does not reliably predict development of chronic back pain. According to new research, more important factors include general health status, functional impairment, and psychological factors such as maladaptive pain-coping behaviors and the presence of psychiatric comorbidities.

Writing in the April 7, 2010 edition of the Journal of the American Medical Association researchers noted that 85% of primary care patients with low back pain have conditions that are considered to be nonspecific, without evidence of serious underlying disorders (or “red flags”) such as cancer, infection, or anatomic defects [Chou and Shekelle 2010]. The question is, how can clinicians determine at early stages whether a patient with acute or subacute nonspecific low back pain will go on to develop a much worse, chronic back pain condition?

To identify so-called “yellow flag factors” associated with prolonged or delayed recovery from nonspecific low back pain, the researchers systematically reviewed prospective studies of patients with fewer than 8 weeks of low back pain. From study data they calculated likelihood ratios to determine factors most predictive of developing persistent disabling (chronic) low back pain at 3 to 6 months and at one year. A total of 20 studies evaluating 10,842 patients were included in their analysis.

The most useful predictors of worse outcomes — ie, eventual development of chronic low back pain — were…
  • Nonorganic signs indicating a strong psychological component of the pain or intentionally false or exaggerated pain symptoms (eg, Waddell’s signs [more info here] reflecting somatization) were highly predictive of failure to return to work at 3 months and the likelihood of worse outcomes at one year.

  • Patients with maladaptive pain-coping behaviors — such as, avoiding physical movement or activities due to fears of damaging the back, or having excessively negative thoughts about recovery prospects (catastrophizing) — were likely to have worse outcomes at 3 to 6 months and at one year.

  • Higher baseline functional impairment, measured via such instruments as the Oswestry Disability Questionnaire [available here] and others, strongly predicted an increased likelihood of poor outcomes.

  • Lower general health status before the onset of back pain exacerbated the development of chronic pain later on.

  • The presence of psychiatric comorbidities (measured using various scales) had an even stronger negative effect than poor general health.

  • Variables related to the work environment, such as higher work dissatisfaction and greater physical work demands did not predict worse outcomes at 3 months but did so at one year.
Factors that were much less important or useless in predicting the development of chronic disabling low back pain during 12 months, included…
  • High pain intensity at baseline predicted worse outcomes at 3 to 6 months but not at one year.

  • Presence of radiculopathy or leg pain only slightly increased the odds of worse outcomes at any time point, and the absence of such pain had no predictive value at all.

  • A history of prior low back pain episodes was not useful in predicting worse outcomes at any time point.

  • Demographic variables — age, sex, education level, body weight, and smoking status — did not appear to have any value for predicting the development of persistent back pain [contrary to earlier research that found these factors of some importance].
The researchers also examined several back pain risk-prediction instruments (eg, questionnaires), some of which were useful in predicting outcomes but none of which were extensively validated or reliable. They conclude that the approach to patients with low back pain should include clinical assessments looking for maladaptive pain-coping behaviors, the presence of nonorganic signs (somatization), high levels of baseline functional impairment, low general health status, and psychiatric comorbidities. The presence of these “yellow flags” would predict worse outcomes during the following 12 months; conversely, low levels of fear avoidance and low baseline functional impairment are the most useful items for predicting the likelihood of recovery.

COMMENTARY: Low back pain is extremely common, accounting for 2% of all office visits in the U.S. and the high prevalence of nonspecific or idiopathic back pain disorders is a quandary for both practitioners and their patients. Early identification of patients more likely to develop persistent disabling symptoms could help guide decisions regarding follow-up and management; in the absence of “yellow flags” as identified in this study, Chou and Shekelle [2010] suggest that healthcare providers can provide patients with informed reassurance of a quick recovery.

It also seems important to observe that so many of the factors predicting poor prognoses have psychological foundations. This emphasizes that effective treatments for nonspecific low back pain must go beyond merely prescribing analgesics and recommending physical therapies or other adjunctive measures to considerations of the whole person, including personal beliefs, psychiatric status, and behaviors that may be counterproductive to recovery. As we have started emphasizing in our new series of blogposts on pain-and-the-brain [here], there are both conscious and subconscious neurobiological forces at work that shape the experience of pain and individual responses to it, potentially engendering chronic pain as a complex brain disease.

REFERENCE: Chou R, Shekelle P. Will this patient develop persistent disabling low back pain? JAMA. 2010;303(13):1295-1302 [abstract].