A proposed definition of remission from chronic pain, based on retrospective evaluation of 24-month outcomes with spinal cord stimulation

ABSTRACT

Objective: In the treatment of chronic diseases, remission is commonly used as a meaningful treatment goal, synonymous with the absence of significant clinical signs and symptoms of a disease, but not representing a cure. The objective of this paper is to propose a definition for remission for use as an outcome to evaluate the long-term efficacy of therapies for chronic pain.

Methods: Data from a randomized clinical trial (NCT01609972) testing the efficacy of spinal cord stimulation in low back and leg pain subjects was used to evaluate the association between pain and functional outcomes and identify the cut-off value to predict remission. Available data over 24-month assessment period included visual analog score (VAS), disability (Oswestry Disability Index [ODI]), patient and clinician global impression of change (PGIC and CGIC), and patient satisfaction. Cluster analysis, Pearson’s correlation coefficients, sensitivity, and specificity analyses were used to evaluate its utility in predicting higher patient functionality and satisfaction.

Results: Though the term remission has been used in the chronic pain field, a consistent definition has not been previously established. Based on the analysis of the clinical data, we propose that a sustained (≥6 months) pain score of ≤3.0 cm out of 10 cm on VAS be defined as remission. Applying this definition to the clinical trial data: subjects in remission at 24 months versus non-remitters were significantly more likely to be in the highest functional category of minimally disabled according to the ODI (31.5 vs. 8.2%, respectively, p = 0.001), and be ‘very satisfied’ (75.7 vs 22.6%, respectively, p < 0.001).

Conclusions: The validity of the proposed definition of remission is supported by the persistence of remission in this study group, and its correspondence with patient satisfaction, and reduced disability. Further evaluation of the definition using clinical data from other long-term studies is needed.

Trial registration: ClinicalTrials.gov identifier: NCT01609972.

KEYWORDS:

• Spinal cord stimulation
• remission
• chronic pain

Acknowledgments

The authors would like to thank the SENZA-RCT investigators for contributing to the consensus definition of remission in chronic pain and Richard G. Holcomb, PhD for performing the statistical analyses associated with defining remission in chronic pain. The authors would also like to express their gratitude for the guidance and input provided by Eugene Carragee, MD.

Declaration of interest

K Amirdelfan, L Kapural, R Vallejo, and C Yu serve as consultants to and receive research grants from manufacturers of spinal cord stimulation devices and other pain treatments. E.K. serve as consultant to manufacturers of spinal cord stimulation devices and other pain treatments. B Gliner, A Rotte, R Province-Azalde and D Caraway are employees of Nevro Corp. BT Sitzman received fees from Nevro Corp as a scientific advisor. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial relationships to disclose.

Additional information

Funding

This manuscript was funded by Nevro Corp.