Spine surgery patients are most likely to control pain poorly after a procedure if they are female, younger than age 70 years, and record higher depression scores, according to a recent report.1

“We wondered why some patients had more pain control than others,” says Michael Yang, MD, MSc, MBiotech, study co-author and neurosurgery resident at the University of Calgary.

Yang and colleagues conducted a retrospective cohort study of data from adult patients in the Canadian Spine Outcomes and Research Network registry. The patients underwent elective cervical or thoracolumbar spine surgery and had been admitted to the hospital. They found 57% of 1,300 spine surgery patients had experienced poorly controlled pain during the first 24 hours after surgery.

“We could not study ambulatory patients because we evaluated their pain experience in the first 24 hours. If they were discharged before then, they were not evaluated in our work,” says Steven Casha, MD, PhD, FRCSC, study co-author and associate professor at the University of Calgary.

The authors developed a tool that could predict postoperative pain for spine surgery patients called the three-tier Calgary Postoperative Pain After Spine Surgery (CAPPS) score. Using CAPPS scores, investigators made three groups: low-risk, high-risk, and extreme-risk groups.

Investigators took 85 potential variables that came from the registry and narrowed these to 25 they could analyze with statistical models. A consensus of three neurosurgeons, one neurologist, and one biostatistician chose the 25 variables that could help predict poor postoperative pain.

The variables were selected for the likelihood they would offer additional prognostic information beyond what other variables provide. Also, researchers picked these variables because they are feasible for any spine center to collect.

“These 25 variables were then analyzed using a multivariable logistic regression model,” Yang explains. “From this model, seven predictors were found to be significant.”

On top of gender, age, and depression scores, additional variables associated with poorly controlled pain were: preoperative use of opioids, higher intensity of preoperative neck or back pain, previous fusion surgery, and three or more prior operations. “Almost all of the patients had neck and back pain,” Casha notes. But those patients with higher-intensity neck and back pain were the ones more likely to struggle with pain control after spine surgery.

Using data from the seven predictors of poorly controlled post-op pain, investigators determined the odds that patients would experience poor pain outcomes. They predicted that 32% of the low-risk group would control pain poorly, 63% of the high-risk group would control pain poorly, and 85% of the extreme-risk group would control pain poorly.

“To ensure that our CAPPS score is accurate, we applied this score to a separate patient population — 30% of our data set — and showed that the predicted and the actual observed probability of poor pain control was very similar,” Yang says.

Using the CAPPS score, physicians could tailor individualized treatment to a specific patient, Casha says. “This is a simple tool that should be easy to adopt,” he offers. “It can be used to educate people to their sensitivity to pain and to prepare them for the postoperative pain experience.”

For instance, if a patient has taken opioids before surgery, then physicians could recommend they reduce or eliminate their opioid use before the procedure, Casha suggests. “If you get someone off daily opioids, then you could change their CAPPS score, and perhaps that would lead to a better pain experience.”

Casha says future research may uncover even more variables. For example, sleep patterns could be one. If patients are insomniacs, they might struggle with pain control. Anxiety, separate from depression, could be another. “Pain is a subjective thing,” Casha observes. “One person will express it as a catastrophe, while someone else considers it livable.”

Researchers can measure patients’ heart rates and other vital signs that might indicate pain, but the responses would be variable. “At the end of the day, pain is what a person experiences, and it’s how well they tolerate it that matters,” Casha observes.

REFERENCE

  1. Yang MMH, Riva-Cambrin J, Cunningham J, et al. Development and validation of a clinical prediction score for poor postoperative pain control following elective spine surgery. J Neurosurg Spine 2020; Sep 15;1-10. doi: 10.3171/2020.5.SPINE20347. [Online ahead of print].