Risk factors for new-onset persistent low-back pain following nonobstetric surgery performed with epidural anesthesia.

BACKGROUND

The aim of this trial was to identify risk factors for persistent low-back pain (LBP) of new onset following nonobstetric surgery performed with lumbar epidural anesthesia.

METHODS

Four-hundred eighty-three patients with no history of LBP were screened for backache 2 days, 10 days, and 13 weeks after nonobstetric surgeries were performed with lumbar epidural anesthesia. Demographic data, details of epidural techniques, and operative data were compared in patients who developed back pain that persisted for 13 weeks with those patients who did not. Multivariate logistic regression analysis was performed to identify predictors of persistent LBP.

RESULTS

Ten patients (2.1%) consistently experienced clinically significant LBP at 2 days, 10 days, and 13 weeks after surgery; they were labeled as having persistent LBP. Multivariate analysis showed that higher body mass index (P < 0.001), multiple attempts at epidural placement (P = 0.026), surgery in the lithotomy position (P = 0.013), and duration of surgery exceeding 2½ hrs (P = 0.025) were independent risk factors for persistent LBP. As much as 51% of variation in the outcome measure could be explained by the model (R = 0.51), which had an overall accuracy of 98.1%.

CONCLUSIONS

Persistent LBP after nonobstetric surgery performed with lumbar epidural anesthesia is rather rare. Independent risk factors for this untoward outcome are higher body mass index, multiple trials at epidural placement, surgery in the lithotomy position, and operative time exceeding 2½ hrs. These results need to be validated by prospective trials using larger cohorts.