Comparison 2. Local or regional anaesthesia for the prevention of persistent postoperative pain (classical analysis).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 PPP after thoracotomy	6		Odds Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 Three months follow‐up	5	428	Odds Ratio (M‐H, Random, 95% CI)	0.70 [0.40, 1.20]
1.2 Six months follow‐up	5	370	Odds Ratio (M‐H, Random, 95% CI)	0.39 [0.24, 0.63]
2 PPP after cardiac surgery	2		Mean Difference (IV, Random, 95% CI)	Subtotals only
2.1 Three months follow‐up	2	116	Mean Difference (IV, Random, 95% CI)	‐0.77 [‐1.74, 0.20]
3 PPP after breast cancer surgery	19		Odds Ratio (M‐H, Random, 95% CI)	Subtotals only
3.1 Three months follow‐up	11	966	Odds Ratio (M‐H, Random, 95% CI)	0.34 [0.19, 0.61]
3.2 Six months follow‐up	9	515	Odds Ratio (M‐H, Random, 95% CI)	0.56 [0.37, 0.84]
3.3 12 months follow‐up	2	113	Odds Ratio (M‐H, Random, 95% CI)	0.63 [0.04, 10.47]
4 PPP after caesarean section	4		Odds Ratio (M‐H, Random, 95% CI)	Subtotals only
4.1 Three months follow‐up	2	137	Odds Ratio (M‐H, Random, 95% CI)	1.09 [0.39, 3.07]
4.2 Six months follow‐up	3	492	Odds Ratio (M‐H, Random, 95% CI)	0.44 [0.26, 0.74]
5 PPP after amputation	2		Odds Ratio (M‐H, Random, 95% CI)	Totals not selected
6 PPP after laparotomy	2		Odds Ratio (M‐H, Random, 95% CI)	Totals not selected
7 PPP after hernia repair	2		Odds Ratio (M‐H, Random, 95% CI)	Totals not selected
8 PPP after hysterectomy	2	135	Mean Difference (IV, Random, 95% CI)	1.90 [‐1.23, 5.02]
8.1 Three months follow‐up	2	135	Mean Difference (IV, Random, 95% CI)	1.90 [‐1.23, 5.02]