Friday, February 18, 2011

Role of Age in Origin of Chronic Low Back Pain

Back PainNew data suggest that intervertebral lumbar disc disruptions are the most common cause of chronic low back pain in younger adults; whereas, facet or sacroiliac joints are the more likely sources of pain as people age. At the same time, spinal stenosis is a common cause of lower back pain in older adults, and the use of more complex and costly surgeries to correct this problem is surprisingly increasing dramatically.

Researchers at Virginia Commonwealth University conducted a retrospective chart review to estimate the association of prevalence and age of several painful lower back conditions: lumbar internal intervertebral disc disruption, lumbar facet joint pain, sacroiliac joint pain, spinal and pelvic insufficiency fractures, interspinous ligament injury/Baastrup's Disease, and soft tissue irritation due to spinal-fusion hardware [DePalma et al. 2011]. A total of 170 cases from 156 patients who underwent a number of diagnostic procedures to determine the source of chronic low back pain were included in the final analysis.

Writing in the February 2011 edition of the journal Pain Medicine the investigators reported that the prevalence of internal disc disruption, facet joint pain, and sacroiliac joint pain was 42%, 31%, and 18%, respectively, and these were the major causes of low back pain in their sample. Patients with internal disc disruption were significantly younger than those with facet joint pain or sacroiliac joint pain. Conversely, increased age — up to about 70 years of age — was associated with a decreased probability of internal disc disruption but increased probabilities of facet joint pain and sacroiliac joint pain as the source of low back pain.

A separate research report suggests that lumbar spinal stenosis also becomes more common as people age and it is a common indication for surgical intervention for chronic lower back pain. The study, reported in the Journal of the American Medical Association (JAMA), examined trends in the use of different types of stenosis operations and the association of complications and resource use with surgical complexity [Deyo et al. 2010]. Investigators conducted a retrospective analysis of operations on a large cohort of Medicare recipients (≥65 years of age) undergoing surgery for lumbar stenosis and grouped into 3 gradations of invasiveness: decompression alone, simple fusion (involving 1 or 2 disk levels and a single surgical approach), or complex fusion (more than 2 disk levels or combined anterior and posterior approach).

Comparing years 2002 through 2007, overall spinal surgery rates declined slightly, but the rate of complex fusion procedures increased 15-fold, from 1.3 to 19.9 per 100,000 Medicare beneficiaries. Life-threatening complications also multiplied with increasing surgical invasiveness, from 2.3% among patients having decompression alone to 5.6% among those having complex fusions. A similar pattern was observed for rehospitalization within 30 days, which occurred for 7.8% of patients undergoing decompression and 13.0% having a complex fusion. Adjusted mean hospital charges for complex fusion procedures were nearly $81,000 compared with about $24,000 for decompression alone.

The authors conclude that the frequency of complex fusion procedures for spinal stenosis increased while the frequency of decompression surgery and simple fusions decreased. At the same time, compared with decompression, simple fusion and complex fusion were associated with increased risks of major complications, 30-day morbidity, and resource use.

CLINICAL COMMENTS: We have cautioned previously [here] that retrospective studies — whether chart reviews as in the first study or data-mining research in the second study — are limited by the completeness and accuracy of available information. For example, in the second study, Deyo and colleagues [2010] concede that surgeons tailor operations to the nature, extent, and location of an individual's pathology, but the claims data used in their analyses did not indicate severity or extent of anatomic changes, patient symptoms, or functional status.

Decompression, the least invasive or complicated surgical approach and with a faster recovery time, involves removal of bone, bone spurs, or ligaments that are impinging on spinal nerves. Why the rate of more complex surgeries has increase so dramatically — 15-fold in just 6 years — is uncertain, but some experts find the trend alarming, according to Deyo et al. in the JAMA article. They note, “The introduction and marketing of new surgical devices and the influence of key opinion leaders may stimulate more invasive surgery, even in the absence of new indications.” They further suggest that, “Financial incentives to hospitals and surgeons for more complex procedures may play a role as may desires of surgeons to be local innovators.”

On the other hand, improvements in surgical and anesthetic technique, and better supportive care, may make more invasive and complex surgery feasible; whereas, the risks of such complex procedures formerly might have been more prohibitive. Still, Deyo et al. emphasize that, until additional and compelling data are available to support better pain relief or function with more complex surgeries, using the least invasive procedure that accomplishes clinical goals would be most appropriate.

> DePalma MJ, Ketchum JM, Saullo T. What Is the Source of Chronic Low Back Pain and Does Age Play a Role? Pain Medicine. 2011;12: 224–233 [
abstract here].
> Deyo RA, Mirza SK, Martin BI. Trends, Major Medical Complications, and Charges Associated With Surgery for Lumbar Spinal Stenosis in Older Adults. JAMA. 2010;303(13):1259-1265 [
abstract here].