Investigating protective strategies against chronic neuropathic pain (CNP) after breast cancer surgery entails using valid screening tools. The DN4 (Douleur Neuropathique en 4 questions) is 1 tool that offers important research advantages. This prospective 6-month follow-up study seeks to validate the DN4 and assess its responsiveness in screening for CNP that satisfies the International Association for the Study of Pain (IASP) definition and fulfills its grading system criteria after breast tumor resection with and without paravertebral blocks (PVBs). We randomized 66 females to standardized general anesthesia and sham subcutaneous injections, or PVB and total intravenous anesthesia. The 6-month CNP risk was assessed using the IASP grading system and the DN4 screening tools. We evaluated the DN4 sensitivity, specificity, and responsiveness in capturing the impact of PVB on the CNP risk relative to the IASP grading system. Data from 64 patients showed similar demographic characteristics in both groups. Twenty patients in both groups met the grading system CNP criteria; among these, 18 patients also met the DN4 CNP criteria. Furthermore, 15 patients in both groups did not meet the grading system CNP criteria; among these, 9 patients also did not meet the DN4 CNP criteria. Therefore, the sensitivity and specificity of the DN4 were estimated at 90% and 60%, respectively. Both screening tools suggested that PVB reduced the 6-month CNP risk. Our results suggest that the DN4 can reliably identify CNP at 6 months after breast tumor resection and detect the preincisional PVB effect on the risk of developing such pain.
The DN4 questionnaire reliably identifies chronic neuropathic pain after breast tumor resection and detects the paravertebral block treatment effect on the risk of this pain.
aDepartment of Anesthesia, University of Toronto, Toronto, Ontario, Canada
bDepartment of Anesthesia, St. Michael's Hospital, Toronto, Ontario, Canada
cKeenan Research Centre, Li Ka Shing Knowledge Institute, Toronto, Ontario, Canada
dDepartment of Anesthesia, Women's College Hospital, Toronto, Ontario, Canada
eDepartment of Surgery, Women's College Hospital, University of Toronto, Toronto, Ontario, Canada
fDepartment of Anesthesia, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
Corresponding author. Address: Department of Anesthesia, St. Michael's Hospital, 30 Bond St, Toronto, ON M5B 1W8, Canada. Tel.: (416) 864-5071; fax: (416) 864-6014. E-mail address: AbdallahF@smh.ca (F. W. Abdallah).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received December 02, 2014
Received in revised form January 04, 2015
Accepted January 21, 2015