Study shows unique characteristics of acute vs. chronic low back pain

By some estimates, up to 85 percent of Americans have experienced low back pain and research reported in The Journal of Pain showed that pain intensity ratings, pain location and sensory and affective variables differ among individuals with acute and chronic low back pain. In some cases, these factors might be predictive of which acute pain patients may develop chronic pain.

Researchers from the Rehabilitation Institute of Chicago and Northwestern University’s Feinberg School of Medicine recruited 40 acute back pain patients and 37 with chronic back pain for the study. The subjects were trained to rate their pain and completed several different questionnaires designed to assess pain intensity, medication use and evidence of affective disorders, such as depression.

The researchers investigated differences in pain characteristics between sub-acute back pain and chronic back pain and their relationship to pain intensity. They noted there is limited information regarding differences in clinical-based features in short-and long-term back pain. The common differentiation for distinguishing types of low back pain are: acute pain lasting less than six weeks, sub-acute pain with duration of seven to 12 weeks and chronic pain lasting three months or longer.

Results showed that pain intensity was significantly higher in the chronic low back patients. Regarding pain location, the study reported sub-acute pain patients had a higher incidence of unilateral radiating pain while chronic pain subjects experienced mostly bilateral pain. Surprisingly, the depression score showed just a slight increase in those with longer pain duration and was considered to be attributable to pain intensity.

The authors concluded that pain intensity and pain location are characteristics that can predict chronic low back pain. They noted that chronic low back pain subjects reported more significant pain than sub-acute pain subjects in their study and there also is published evidence that the location of pain in acute back pain patients may serve as a predictor for development of a chronic condition. According to several reports, patients with sub-acute low back pain who experience discomfort triggered by movement at distal body sites have a poorer prognosis than those in which pain is more localized.