Factors Related to the Prognosis of Chronic Low Back Pain in Older Adults.

IMPORTANCE

Studies on the prognosis of chronic low back pain (CLBP) in older adults are lacking; hence, elucidating the pathophysiology of CLBP in older adults is necessary.

OBJECTIVE

The objective of this study was to analyze the prognosis of CLBP and factors related to its intractability in older adults.

DESIGN

The design was a prospective cohort study.

SETTING

This study was conducted at a national center hospital, which was specialized in geriatric medicine and research.

PARTICIPANTS

We included 361 patients aged ≥65 years with CLBP lasting for >3 months.

INTERVENTION OR EXPOSURE: The nonimprovement group was defined as those who showed no improvement on a visual analog scale (VAS) of <3 for LBP after 12 months of exercise therapy.

MAIN OUTCOMES AND MEASURES: Multivariate analyses of factors related to the intractability of CLBP in older adults, including body composition measured using whole-body dual-energy X-ray absorptiometry, cross-sectional area (CSA) of the paraspinal muscles measured using magnetic resonance imaging, and whole spinal alignment measured using X-rays, were conducted.

RESULTS

Of the 361 patients, 152 (42.1%) had an improved VAS score of <3 within 1 year. In the nonimprovement group, the duration of the disease was significantly longer, VAS score before treatment and red blood cell distribution width (RDW) were higher, high-density lumbar spine volume and CSAs of the paravertebral muscles were significantly lower, and prevalence of disc degeneration was significantly higher. Age, disease duration, VAS score, RDW, and CSA of the lumbar multifidus (LM) at the L4/5 level were significant factors associated with CLBP. Changes in the CSA of the paraspinal muscle were significantly reduced at 12 months in the nonimprovement group compared with the improvement group.

CONCLUSION

The factors affecting the intractability of CLBP were the intensity of pain, RDW, and atrophy of the LM muscles.

RELEVANCE: Paravertebral muscle atrophy progresses over time in intractable LBP. Muscle training centered on the LM muscle of the lower lumbar spine is recommended.