Is Severe Pain Immediately after Spinal Augmentation a Predictor of Long-Term Outcomes?

Discussion

This study demonstrated that severe, postprocedure pain after spine augmentation did not predict greater pain severity at either 1 or 12 months after the procedure compared with patients not experiencing severe, postprocedure pain. This equivalence in pain outcomes was present, though the patients with severe, immediate postprocedure pain presented with greater baseline pain compared with the control group. We did observe that patients with severe pain were more likely to have a worsened medication score, indicating a need for stronger analgesics, at 1 month and 1 year postprocedure compared with patients who did not have severe pain. This finding may explain why patients with severe pain reported similar levels of pain at 1 month and 1 year postprocedure compared with patients without severe pain; however, we could not confirm if or how frequently patients were taking these analgesics. Taken together, these findings are highly relevant to spinal augmentation practitioners, as they can reassure patients that severe, postprocedure pain does not mean that their medium-term and long-term pain outcomes will be suboptimal.

In addition to providing prognostic clarity, our study can also be used to identify which factors, if any, will predict the occurrence of severe, immediate postprocedure pain. The only factor noted to correlate with such pain was the severity of baseline pain, but that parameter alone likely will not provide substantial guidance. Among the numerous factors that logically might predict immediate pain severity—including numbers of treated levels, unipedicular or bipedicular approaches, cement leakage, or chronic fractures that were untreated because they were not amenable to vertebroplasty—none correlated with severe, immediate pain. Patients who had 3 or more levels treated were more likely to receive pain medication immediately after the procedure compared with patients who had fewer levels treated; however, the incidence of reported severe pain was similar between these 2 groups.

Previous studies have evaluated the predictive value of early pain severity after spine augmentations. In a study of 181 vertebroplasty procedures, Hodler et al¹⁶ described that immediate postprocedural pain relief was the best predictor of midterm outcome of vertebroplasty. Weill et al¹⁷ showed that pain reduction achieved initially remained stable in 73% of their patients after 6 months. Heini et al¹⁸ also found stable results after 1 year. Our current study expands on this prior literature by offering larger patient cohorts and detailed analysis of potential factors that might influence long-term outcomes.

Our study had several limitations. First, a large number of patients were excluded from the study on the basis of incomplete records at 3 hours postprocedure or at 1 month or 1 year postprocedure. It is unclear how this may have affected the findings of the study. Second, although pain is the most common complaint and can be debilitating, the use of the subjective pain scoring (0–10) was likely a suboptimal evaluation tool of the effectiveness of vertebroplasty.^{19⇓⇓–22} In some cases in our study, pain at the puncture site continued for a few days after the procedure; therefore, VAS scores may have improved further if they had been evaluated later.²⁰ Better functional assessment of patient response to vertebroplasty is likely necessary, as subjective assessment of pain scales is subject to substantial interobserver and intraobserver variability. Third, as with most studies on vertebroplasty, there was a potential for bias when patients are evaluated at follow-up. It is possible that the nurse or physician administering the follow-up questions could have influenced the responses of the patients. Furthermore, it is possible that responses to the follow-up questions were occasionally provided by family members or health care providers who interacted with the patients on a daily basis, particularly with cases in which the patient was unable to give responses because of disability or dementia.¹ Fourth, although we could identify new prescriptions for analgesics after the procedure, we could not confirm if and how frequently patients were actually taking this medication. Finally, new fractures during the follow-up interval may have confounded pain outcomes. A number of patients who had immediate postprocedure relief had recurrent pain symptoms at the short- or long-term follow-up secondary to factors such as new metastatic lesions or development of new compression fractures.