Quantitative Sensory Tests May Predict Outcomes After Spine Surgery

Cold pain hypersensitivity is a potential predictor of pain and disability after spine surgery, according to study results published in Pain.

Chronic back pain is common and in many cases requires surgical intervention; however, up to a third of patients complain of persistent low back pain and disability after low back surgery. The objective of the current trajectory analysis was to explore the predictive potential of quantitative sensory tests (QSTs) of the course of pain and disability after low back surgery.

Baseline QSTs include electrical, pressure, heat, and cold stimulation of the lower back and lower extremity, temporal summation, and conditioned pain modulation. Researchers measured pain intensity and Oswestry Disability Index before surgery and 2, 6, and 12 months after surgery.

The prospective cohort study included 141 patients (57% women; mean age, 61.2±13.3 years) undergoing surgery for chronic low back pain between 2012 and 2015. Of these, 135 (96%), 140 (99%), and 137 (97%) patients presented at the 2-, 6-, and 12-month follow-up, respectively.

Twenty-two patients (16%) reported complete recovery after surgery, and 67 patients (48%) had incomplete recovery. Both groups reported a marked reduction in pain and disability within 2 months after surgery, with a subsequent continuing but slow decrease.

Multivariable ordinal logistic regression showed cold pain sensitivity at the leg was an independent predictor of poor recovery (odds ratio [OR] 2.98; 95% CI, 1.27-7.00; P =.012). In addition, the predicted pain and disability after surgery were better for married patients (OR 0.36; 95% CI, 0.15-0.84; P =.017) and worse for long pain duration (OR 3.56/2 standard-deviation increase; 95% CI, 1.37-9.26; P =.009).

Cold pain hypersensitivity at the leg and at the back was associated with a nearly 4-fold (OR 3.85; 95% CI, 1.85-8.02; P <.001) and a 2-fold (OR 2.13; 95% CI, 1.10-4.11; P =.024) increased risk for worse recovery after surgery, respectively.

Trajectory analysis, which allows identifying predictors that had not been significantly associated with pain or disability at 12 months, determined cold pain hypersensitivity to be a strong predictor of worse recovery, including pain and disability at a 12-month follow-up.

The lack of external validation and limited number of trajectory groups were the main limitations of the study.

“Noticeably, cold pain test can be delivered very quickly, making it suitable for large multisite validation studies and of potential clinical use,” wrote the researchers. “The availability of a clinically applicable prognostic QST may improve our ability to reduce the failure rate of spine surgery with associated pain, disability, and socioeconomic consequences.”

Reference

Müller M, Bütikofer L, Andersen OK, et al. Cold pain hypersensitivity predicts trajectories of pain and disability after low back surgery: a prospective cohort study. Published online July 28, 2020. Pain. doi: 10.1097/j.pain.0000000000002006