Summary of results
| Outcomes | Trials (n) | Included studies | Participants (n) | RR, random effect (95% CI) | Heterogeneity (I²) (%) | Quality of evidence (GRADE) | NNT |
| Incidence of CPSP at 3 months | 6 | 25 29 30 32–34 | 420 | 0.78 (0.57 to 1.06) | 49 | ⊕⊕⊕⊝ 2 | NA |
| Incidence of CPSP at 6 months | 7 | 5 19 26 28 30 33 34 | 2161 | 0.82 (0.62 to 1.08) | 51 | ⊕⊕⊕⊝ 1 | NA |
| Incidence of CPSP at 12 months | 3 | 5 19 29 | 1826 | 0.45 (0.14 to 1.41) | 82 | ⊕⊕⊕⊝ 1 | NA |
| Incidence of CPSNP at 6 months | 8 | 5 19 26–29 31 33 | 2087 | 0.48 (0.27 to 0.85) | 59 | ⊕⊕⊝⊝ 1, 3 | 12.0 (7–56) |
Primary outcome: The level of evidence was assessed by the GRADE method, from very low ⊕⊝⊝⊝ to high ⊕⊕⊕⊕. 1: downgrade for inconsistency (I2 >50%): serious; 2: downgrade for imprecision: optimal information size not reached: very serious; 3: downgrade for bias.
CPSNP, chronic postsurgical neuropathic pain; CPSP, chronic postsurgical pain; GRADE, Grading of Recommendations, Assessment, Development and Evaluations; NA, not applicable; NNT, number needed to treat; RR, risk ratio.