Thursday, March 24, 2011

'Surgeon Enthusiasm' Increases Low Back Surgeries

Back PainA new study proposes that surgeons in some geographic areas are more likely to recommend surgery for lower back problems, and a major driving factor appears to be "surgeon enthusiasm" for the procedures. In contrast, surgery rates are unrelated to comparable enthusiasm among primary care physicians or patients.

Reporting in the March 14, 2011 issue of the journal Spine researchers examined healthcare databases in Ontario, Canada, spanning 2002 to 2006 to identify more than 10,000 surgeries — such as decompression/laminectomy or fusion — performed for degenerative disease of the lumbar spine in patients ≥50 years of age. Disease processes included conditions, like "slipped" vertebrae caused by bone degeneration (spondylolisthesis) and narrowing of the spinal canal (stenosis), for which there is allegedly strong evidence for surgical effectiveness. The researchers found that there were significant variations in spinal surgery rates across small geographic regions.

Differences in back surgery rates between Ontario counties were compared with a previous survey in which surgeons, family physicians, and patients with back pain had been asked about their preferences for spinal surgery. In that study, presented with different scenarios, surgeons were asked whether they would recommend surgery, family physicians whether they would rate surgery as appropriate, and patients whether they would consider surgery. The results showed that surgeons had higher “enthusiasm” (ie, were more likely to recommend surgery) in counties with higher rates of spinal surgery. There was a 20% difference in surgery rates between the top and bottom quartiles of surgeon enthusiasm ratings.

In contrast, enthusiasm on the part of family physicians and patients with back pain were unrelated to variations in surgery rates, and neither were local differences in the rates of degenerative spine disease. Factors significantly affecting surgery rates included demographic factors like older age, male sex, and lower income of patients, along with the greater presence of magnetic resonance imaging (MRI) scanners in the county. However, surgeon enthusiasm ratings were the dominant and only potentially modifiable factor influencing surgical rates, according to the study authors.

NOTES & COMMENTARY: Previous studies using Medicare data have similarly found large regional variations in the rates of lumbar spine surgery across United States counties. However, we just recently discussed a study in which long-term outcomes, including return to work, were actually better without lumbar fusion surgery for chronic low back pain [UPDATE here].

Variations in surgery rates and their appropriateness raise important concerns: If rates appear to be excessively high in certain locales or groups of patients, then some patients may be receiving unnecessary surgeries for low back pain and healthcare resources are being wasted. If surgery rates are unusually low, it could suggest that some patients who might benefit from spinal surgery are not receiving it. The authors of this present study suggest that “surgeon enthusiasm” is a primary influence driving regional variations in lumbar spine surgery, and may be a factor that is most amenable to change for providing appropriate access to care. However, what qualifies more specifically as “enthusiasm” and why surgeons might vary in this factor need better definition.

Furthermore, interested readers may want to take a close look at some of the data in this study. For major variables, the researchers reported calculating incidence rate ratios (IRRs) — a type of Risk Ratio — controlling for county demographics, socioeconomic measures, prevalence of disease, and community resources. Counties with higher rates of surgery had higher surgeon enthusiasm for surgery (IRR=1.26, p<0.013), older (IRR=2.17, p<0.0001) male (IRR=1.19, p<0.0001) patients with lower income (IRR=0.89, p<0.0015), and a greater presence of MRI scanners (IRR=1.30, p<0.004).

While all of these values were statistically significant, only patient age appeared to have a large clinically significant effect size; meanwhile, the key variable — surgeon enthusiasm (at an IRR=1.26, or 26% relative rate increase) — exhibited only a medium effect size. Therefore, while this study seems to be of interest, if we take into consideration qualitative effect sizes and the fact that the study involved a retrospective “data mining” approach, the overall strength of evidence might be viewed as being only moderate at most. [Quality of evidence issues are discussed in our ongoing UPDATES series, “Making Sense of Pain Research” here.]

REFERENCE: Bederman SS, Coyte PC, Kreder HJ, et al. Who's in the Driver's Seat? The Influence of Patient and Physician Enthusiasm on Regional Variation in Degenerative Lumbar Spinal Surgery: A Population-Based Study. Spine. 2011(Mar 15)36(6):481-489 [abstract here].