By Joshua Weaver, MD
Assistant Professor of Clinical Neurology, Weill Cornell Medical College
A population-based, prospective cohort study of women in the United Kingdom found no association between the number of lumbar segments with radiographic pathology and severity of back pain-related disability.
Chen L, Perera RS, Radojcic MR, et al. Association of lumbar spine radiographic changes with severity of back pain-related disability among middle-aged, community-dwelling women. JAMA Netw Open 2021;4:e2110715.
Low back pain is the leading cause of disability worldwide and is the most common reason for patients to see their primary care physician. Although most guidelines recommend imaging for back pain only when specific criteria, such as neurological deficits or an underlying condition, are met, lumbar spine imaging often is performed by doctors on patients who do not have these signs or symptoms. Questions remain regarding whether the presence and severity of degenerative changes seen on such imaging relates to the severity of disability that people experience.
In this study, 1,003 predominantly white women from a large practice in the United Kingdom were examined as an initial baseline. They had similar weight, height, and body mass index (BMI) compared to the general population. They were re-evaluated with questions regarding physical activity at year 6 and again at year 9, along with lateral lumbar spine radiographs to provide data for a cross-sectional analysis. The participants then were re-evaluated at year 15 for a longitudinal analysis.
The radiologist reviewing the radiographs was blinded to clinical information and patient identity. A validated grading scale known as Kellgren-Lawrence (K-L) was used to measure osteoarthritis at each lumbar disc level, and this was the primary exposure. As secondary exposures, a semi-quantitative assessment of both disc space narrowing and osteophytes at each lumbar segment was used. The primary outcome of back pain-related disability was assessed using a non-validated back pain questionnaire at years 9 and 15, with a score ranging from 0 to 16 (higher values correspond to more severe disability).
A total of 650 women were included at year 9 for the cross-sectional analysis, and a total of 443 were included at year 15 for the longitudinal analysis. More than 80% of women in both analyses had either never smoked tobacco or had quit. The mean BMI was 27. Just more than 67% of women in both analyses reported no back pain. More than three-fourths of participants reported jobs or housework that was “active” at least half the day; more than half reported no regular exercise.
Based on the K-L osteoarthritis grading scale, women who had one or more lumbar segments with K-L based changes were not statistically more likely to have more disability in both the cross-sectional and longitudinal analyses. This also was true when adjustments were made for physical activity. There was no trend between the number of segments involved and the severity of disability.
Similarly, there was no association between either the osteophyte grade-based score or the disc space narrowing grade-based score and the severity of back pain-related disability in both cross-sectional and longitudinal analyses. There were no interactions found with confounders such as age, BMI, or smoking status.
COMMENTARY
There have been mixed data in the literature regarding the association of findings on lower back imaging and back pain symptoms or disability. This is a large study that provides a detailed and quantified score of degenerative changes in the lumbar spine to examine — not only cross-sectionally but longitudinally — their association with back pain-related disability.
An important limitation of the study is its homogenous patient population of middle-aged white women in the United Kingdom, and these results may not be generalizable to different populations across the world. Another limitation in this study includes the lack of data on other radiographic features that might correlate to back pain or disability, such as spondylolisthesis or vertebral body height. Various anatomical features, such as central stenosis, foraminal stenosis, or nerve root impingement, would be better identified on computed tomography (CT) or magnetic resonance imaging (MRI) modalities.
Regardless, this is an important study that highlights the fact that degenerative changes seen on lower back imaging may not (and often do not) correlate with back pain-related disability. Thus, lumbar X-rays are not useful in making management decisions regarding pain control in this population. This ties in nicely with a prior study done in 2015 that looked at lumbar spine MRI imaging of asymptomatic people ranging from 20 to 90 years of age, finding that degenerative changes increased with age and were exceedingly common (e.g., in those age 60 years, 50% had facet degeneration, 69% had disc bulges, and 88% had disc degeneration) despite not causing pain.1
Future studies should include a more diverse patient population regarding age, gender, and race. The association between imaging findings and back pain, not just back pain-related disability, would be useful to explore. Other imaging features should be included, and although more costly, the use of MRI would provide more anatomical information potentially relevant to the cause of back pain and disability.
REFERENCE
- Brinjikji W, Luetmer PH, Comstock B, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol 2015;36:811-816.
