Paravertebral block for the prevention of chronic postsurgical pain after breast cancer surgery

Patients frequently report chronic postsurgical pain (CPSP) after breast cancer surgery (BCS). The paravertebral block (PVB) is an effective technique to reduce acute postoperative pain after BCS, but its efficacy in preventing CPSP is unclear. This meta-analysis evaluates the efficacy of PVB in preventing CPSP after BCS. We searched Medline, Embase, CENTRAL, Database of Abstracts of Reviews of Effects, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform for studies comparing PVB with control for CPSP prevention after BCS, from inception to April 2020. The primary outcome was CPSP at 6 months, and the secondary outcomes were CPSP at 3 and 12 months, chronic postsurgical neuropathic pain (CPSNP) at 6 months, and PVB-related complications. Data were pooled and analyzed with a random-effects model, and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system was used to evaluate the certainty of evidence. A total of 12 studies were included in the study; data for the 6-month time point from 7 studies (2161 patients) were analyzed, and no difference was found between PVB and control in terms of efficacy in preventing CPSP after BCS (risk ratio (RR) 0.82 (95% CI 0.62 to 1.08)), with a moderate quality of evidence according to the GRADE system. Similar results were obtained at 3 and 12 months (RR 0.78 (95% CI 0.57 to 1.06), RR 0.45 (95% CI 0.14 to 1.41), respectively). Data for the 12-month time point from seven studies (2087 patients) were analyzed and showed that PVB protected against CPSNP, with low quality of evidence (RR 0.51 (95% CI 0.31 to 0.85)). In conclusion, CPSP was not found significantly prevented by PVB after BCS despite the limits in the included studies; nevertheless, PVB could prevent CPSNP by impacting the transition from acute to chronic pain.