Comparison 4. Procedure time for first‐pass cannulation.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
4.1 Difficulty levels defined by original studies	6	1564	Mean Difference (IV, Random, 95% CI)	61.44 [10.40, 112.49]
4.1.1 Difficult	2	219	Mean Difference (IV, Random, 95% CI)	119.85 [88.64, 151.05]
4.1.2 Moderate	1	401	Mean Difference (IV, Random, 95% CI)	95.20 [72.77, 117.63]
4.1.3 Easy	1	596	Mean Difference (IV, Random, 95% CI)	94.80 [81.15, 108.45]
4.1.4 No restriction by intravenous access difficulty level	2	348	Mean Difference (IV, Random, 95% CI)	‐11.31 [‐58.36, 35.74]
4.2 Difficulty levels defined by the success rate with the landmark method	6	1564	Mean Difference (IV, Random, 95% CI)	61.44 [10.40, 112.49]
4.2.1 Difficult	1	192	Mean Difference (IV, Random, 95% CI)	120.60 [88.30, 152.90]
4.2.2 Moderate	3	749	Mean Difference (IV, Random, 95% CI)	23.01 [‐39.89, 85.92]
4.2.3 Easy	2	623	Mean Difference (IV, Random, 95% CI)	94.98 [81.42, 108.55]