Table 3. Effectiveness outcomes.

Outcome	S group	L group	RR or median difference (95% CI)	P value
Primary outcome
CPSP at 3 mo	13 (33.3)	5 (12.8)	0.600 (0.399–0.902)	0.032
Secondary outcomes
CPSP at 1 mo	7 (17.5)	3 (7.3)	2.687 (0.643–11.235)	0.194
CPSP at 6 mo	11 (29.7)	4 (10.5)	0.591 (0.388–0.900)	0.038
SF-MPQ scores (0–45)
At 1 mo	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.195
At 3 mo	33.0 (0.0–35.0)	0.0 (0.0–29.0)	0.0 (0.0–0.0)	0.022
At 6 mo	29.0 (0.0–34.0)	0.0 (0.0–28.3)	0.0 (0.0–0.0)	0.037
SF-MPQ-S scores (0–33)
At 1 mo	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.189
At 3 mo	24.0 (0.0–27.0)	0.0 (0.0–21.0)	0.0 (0.0–0.0)	0.019
At 6 mo	20.0 (0.0–24.0)	0.0 (0.0–21.2)	0.0 (0.0–0.0)	0.039
SF-MPQ-A scores (0–12)
At 1 mo	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.155
At 3 mo	9.0 (0.0–11.0)	0.0 (0.0–8.0)	0.0 (0.0–0.0)	0.024
At 6 mo	9.0 (0.0–9.2)	0.0 (0.0–7.0)	0.0 (0.0–0.0)	0.021
Neuropathic pain*
At 1 mo	4 (10.3)	2 (4.9)	2.229 (0.384–12.923)	0.426
At 3 mo	6 (15.8)	4 (10.3)	1.641 (0.424–6.347)	0.470
At 6 mo	4 (11.1)	3 (7.9)	1.458 (0.303–7.023)	0.707
Pain severity†
At 1 mo	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.397
At 3 mo	0.0 (0.0–2.0)	0.0 (0.0–0.5)	0.0 (0.0–0.0)	0.452
At 6 mo	0.0 (0.0–0.3)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.622
Pain interference‡
At 1 mo	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.347
At 3 mo	0.0 (0.0–2.2)	0.0 (0.0–0.4)	0.0 (0.0–0.0)	0.358
At 6 mo	0.0 (0.0–0.4)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.510

Data are number (%), median (interquartile range), or mean ± SD. *, defined as a score of ≥4 on the DN-4 scale; ^†, scores of pain severity on the Brief Pain Inventory-Short Form; ^‡, scores of pain interference on the Brief Pain Inventory-Short Form. S, control; L, lidocaine; RR, relative risk; CPSP, chronic postoperative pain; SF-MPQ, short-form McGill pain questionnaire; SF-MPQ-S, short-form McGill pain questionnaire-sensitive; SF-MPQ-A, short-form McGill pain questionnaire-affective; DN-4, Neuropathic Pain Score.