Comparison 1. Traumatic needle versus atraumatic needle.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 PDPH by indication	36	9378	Risk Ratio (M‐H, Random, 95% CI)	2.14 [1.72, 2.67]
1.1 Anaesthesia only	30	8401	Risk Ratio (M‐H, Random, 95% CI)	2.21 [1.60, 3.04]
1.2 Myelography only	3	548	Risk Ratio (M‐H, Random, 95% CI)	2.01 [1.34, 3.00]
1.3 Diagnostic lumbar puncture only	3	429	Risk Ratio (M‐H, Random, 95% CI)	2.22 [1.38, 3.58]
2 PDPH by gauge	20		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 22 gauge	5	877	Risk Ratio (M‐H, Random, 95% CI)	2.15 [1.56, 2.97]
2.2 25 gauge	5	1260	Risk Ratio (M‐H, Random, 95% CI)	2.48 [1.56, 3.95]
2.3 27 gauge	11	4076	Risk Ratio (M‐H, Random, 95% CI)	2.87 [1.81, 4.53]
3 PDPH by gender	9		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
3.1 Only women	9	1424	Risk Ratio (M‐H, Random, 95% CI)	2.60 [1.62, 4.17]
4 PDPH/anaesthesia: type of surgery	30		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
4.1 Caesarean section	8	1324	Risk Ratio (M‐H, Random, 95% CI)	3.12 [1.60, 6.10]
4.2 Orthopaedic procedures	3	994	Risk Ratio (M‐H, Random, 95% CI)	1.35 [0.58, 3.19]
4.3 Other surgeries	19	6083	Risk Ratio (M‐H, Random, 95% CI)	2.30 [1.50, 3.51]
5 PDPH by position	20		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
5.1 Lateral position	9	3242	Risk Ratio (M‐H, Random, 95% CI)	4.70 [2.39, 9.24]
5.2 Sitting position	11	2193	Risk Ratio (M‐H, Random, 95% CI)	2.11 [1.52, 2.94]
6 PDPH by age	36		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
6.1 No distinctions by age	34	9063	Risk Ratio (M‐H, Random, 95% CI)	2.17 [1.73, 2.73]
6.2 Only < 18 years	2	315	Risk Ratio (M‐H, Random, 95% CI)	1.69 [0.56, 5.12]
7 AE: paraesthesia	3	573	Risk Ratio (M‐H, Random, 95% CI)	0.96 [0.47, 1.96]
8 AE: backache	12	3027	Risk Ratio (M‐H, Random, 95% CI)	0.94 [0.78, 1.13]
9 Severe PDPH by indication	24	6420	Risk Ratio (M‐H, Random, 95% CI)	1.88 [1.20, 2.94]
9.1 Anesthesia	19	5542	Risk Ratio (M‐H, Random, 95% CI)	1.77 [0.88, 3.53]
9.2 Myelography	4	778	Risk Ratio (M‐H, Random, 95% CI)	1.70 [0.68, 4.28]
9.3 Diagnostic lumbar puncture	1	100	Risk Ratio (M‐H, Random, 95% CI)	3.0 [1.18, 7.63]
10 Any headache by indication	18	4104	Risk Ratio (M‐H, Random, 95% CI)	1.35 [1.17, 1.57]
10.1 Anaesthesia	16	3656	Risk Ratio (M‐H, Random, 95% CI)	1.38 [1.17, 1.63]
10.2 Myelography	2	448	Risk Ratio (M‐H, Random, 95% CI)	1.34 [0.81, 2.21]
11 PDPH sensitivity analysis	3	802	Risk Ratio (M‐H, Random, 95% CI)	2.78 [1.26, 6.15]