Comparison 10. Sensitivity analysis 2 (low risk of bias studies only).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
10.1 First‐pass success of cannulation	6	1638	Risk Ratio (M‐H, Random, 95% CI)	1.24 [0.97, 1.59]
10.1.1 Difficult	2	251	Risk Ratio (M‐H, Random, 95% CI)	1.82 [0.98, 3.37]
10.1.2 Moderate	1	401	Risk Ratio (M‐H, Random, 95% CI)	1.14 [1.02, 1.27]
10.1.3 Easy	1	596	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.85, 0.94]
10.1.4 No restriction by intravenous access difficulty level	2	390	Risk Ratio (M‐H, Random, 95% CI)	1.20 [1.09, 1.33]
10.2 Overall success of cannulation	2	148	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.96, 1.05]
10.2.1 Difficult	1	59	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.92, 1.16]
10.2.2 No restriction by intravenous access difficulty level	1	89	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.96, 1.04]
10.3 Pain	4	1279	Mean Difference (IV, Random, 95% CI)	0.29 [‐0.03, 0.61]
10.3.1 Difficult	1	192	Mean Difference (IV, Random, 95% CI)	0.20 [‐0.61, 1.01]
10.3.2 Moderate	1	401	Mean Difference (IV, Random, 95% CI)	0.10 [‐0.47, 0.67]
10.3.3 Easy	1	596	Mean Difference (IV, Random, 95% CI)	0.60 [0.17, 1.03]
10.3.4 No restriction by intravenous access difficulty level	1	90	Mean Difference (IV, Random, 95% CI)	‐0.10 [‐0.85, 0.65]
10.4 Procedure time for first‐pass cannulation	4	1279	Mean Difference (IV, Random, 95% CI)	69.47 [19.15, 119.78]
10.4.1 Difficult	1	192	Mean Difference (IV, Random, 95% CI)	120.60 [88.30, 152.90]
10.4.2 Moderate	1	401	Mean Difference (IV, Random, 95% CI)	95.20 [72.77, 117.63]
10.4.3 Easy	1	596	Mean Difference (IV, Random, 95% CI)	94.80 [81.15, 108.45]
10.4.4 No restriction by intravenous access difficulty level	1	90	Mean Difference (IV, Random, 95% CI)	‐39.00 [‐75.04, ‐2.96]
10.5 Procedure time for overall cannulation	2	390	Mean Difference (IV, Random, 95% CI)	‐77.42 [‐185.70, 30.86]
10.5.1 No restriction by intravenous access difficulty level	2	390	Mean Difference (IV, Random, 95% CI)	‐77.42 [‐185.70, 30.86]
10.6 Number of cannulation attempts	3	449	Mean Difference (IV, Random, 95% CI)	‐0.31 [‐0.47, ‐0.15]
10.6.1 Difficult	1	59	Mean Difference (IV, Random, 95% CI)	‐0.60 [‐1.51, 0.31]
10.6.2 No restriction by intravenous access difficulty level	2	390	Mean Difference (IV, Random, 95% CI)	‐0.30 [‐0.50, ‐0.11]
10.7 Overall complications	5	1338	Risk Ratio (M‐H, Random, 95% CI)	1.07 [0.62, 1.85]
10.7.1 Difficult	2	251	Risk Ratio (M‐H, Random, 95% CI)	0.77 [0.21, 2.77]
10.7.2 Moderate	1	401	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.38, 1.82]
10.7.3 Easy	1	596	Risk Ratio (M‐H, Random, 95% CI)	2.48 [0.90, 6.87]
10.7.4 No restriction by intravenous access difficulty level	1	90	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.27, 2.54]