HealthDay News — For patients with acute or persistent low back pain, pain and disability improve in the first six weeks of treatment, but low-to-moderate pain and disability tend to persist at one year, results of a meta-analysis show.

Although low back pain is a highly prevalent condition associated with substantial health-care costs, prognosis for patients with chronic low back pain remains uncertain due to conflicting study results. So Luciola da C. Menezes Costa, PhD, of the George Institute for Global Health in Sydney, and colleagues conducted a meta-analysis of inception cohort studies involving patients with acute and persistent low-back pain to investigate prognosis and whether pain and disability have similar courses. A total of 33 cohorts were identified,involving 11,166 participants.

“Our review confirms the broad finding of previous reviews that the typical course of acute low-back pain is initially favorable: there is a marked reduction in mean pain and disability in the first six weeks,” the researchers reported in CMAJ, the journal of the Canadian Medical Association.

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Although only small improvements in pain and disability occur after the first six weeks, patients with acute low back pain had generally had low mean pain and disability scores after one year. The variance-weighted mean pain scores for those with acute pain were 52, 23, 12 and 6, at baseline, six, 26 and 52 weeks, respectively, after the onset of pain.

The researchers observed a similar trend among patients with persistent pain, with substantial improvements in the first six weeks, followed by only very small reductions in average pain and disability between 6 and 52 weeks. However, patients with persistent pain reported higher levels of pain at one year than those with acute pain. The variance-weighted mean pain scores were 51, 33, 26 and 23 at baseline, six, 26 and 52 weeks, respectively.

“We found that patients with acute or persistent low back pain improvedmarkedly in the first six weeks, but beyond this time improvementslowed,” the authors write. “Even at one year, patients hadlow-to-moderate levels of pain and disability.” 

The time course of disability outcomes was similar to that of the pain time course for patients with acute pain, and was slightly better than the pain course for patients with persistent pain.

“Future research is needed to make more precise recommendations on the standardization of recovery definitions of a low-back pain episode and to develop an optimal search strategy to retrieve prognostic studies,” the researchers concluded.

Menezes Costa LC et al. CMAJ. 2012; doi:10.1503/cmaj.111271.