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Genetics may predict leg pain in patients with severe sciatica
A mixed-effect logical regression model was used to determine if genetics play a role in sciatica leg pain.
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Genetics may predetermine persistent leg pain in patients with severe sciatica, according to a recently presented study.
Jon D. Lurie, MD, and his team studied a possible correlation of why some people with sciatica develop persistent leg pain.
“We wanted to look at what the potential role to genetics might be in patients with persistent sciatica,” Lurie said at the International Society for the Study of the Lumbar Spine Annual Meeting 2011.
To find a correlation, the researchers studied 1,244 patients in the SPORT disc herniation cohort. They reviewed patients with sciatica in the cohort with leg pain unexplained by clinicals sociodemographic and treatment variables at 1 year.
“These are patients with severe sciatica with clinical findings corresponding to MRI images that were bad enough to be considered surgical candidates and had their symptoms for at least 6 weeks,” Lurie said.
Predicting pain
The team used a mixed effect logistical regression model to examine “characteristics for predicting a 1-year leg pain score among 44 covariates, including treatment,” according to Lurie.
“We looked at the proportion of the total residual variance that might be explained by patient characteristics,” Lurie said.
The researchers established this proportion as the ratio of the estimated variance of the random individual effect to the total residual variance. Predictors included in the resulting model included baseline sciatica severity, education, litigation status, work status, herniation level, smoking, depression, other comorbidities, epidural injections, physical therapy, duration of symptoms and surgical vs. nonoperative treatment.
“We weren’t interested in the individual predictors,” Lurie said. “We were interested in just how much variance can be explained by everything we know.”
Genetics a predictor
The researchers estimated the random individual effect was 1.13, the residual variance was 1.79 and the corresponding intra-class correlation was 0.404.
“Forty percent of the total residual variance for persistent leg pain was attributable to unidentified factors that may include genotype,” Lurie said. “That is consistent with the animal studies that suggest about 40% to 50% of persistent pain may be genetically determined and we think this supports a rationale for looking at the genetics of pain as opposed to many of the things that we see, which is the genetics of the underlying anatomic disorder.”
Lurie noted that work remains to be done including studies of the genetic contributors to pain. – by Renee Blisard
Reference:
- Lurie JD, Berven S, Boden S, Zhao W, et al. Explained variance in leg pain 1 year after lumbar disc herniation. Paper #40. Presented at the International Society for the Study of the Lumbar Spine Annual Meeting 2011. June 14-18. Gothenburg, Sweden.
- Jon D. Lurie, MD, can be reached at Dartmouth-Hitchcock Medical Center, One Medical Center Dr., Lebanon, NH 03756; 603-650-5000; email: jon.d.lurie@dartmouth.edu.
- Disclosure: Lurie has no relevant financial disclosures.