Comparison 9. Sensitivity analyses 1 (RCTs only).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
9.1 First‐pass success of cannulation	12	2082	Risk Ratio (M‐H, Random, 95% CI)	1.30 [1.07, 1.59]
9.1.1 Difficult	8	695	Risk Ratio (M‐H, Random, 95% CI)	1.50 [1.15, 1.96]
9.1.2 Moderate	1	401	Risk Ratio (M‐H, Random, 95% CI)	1.14 [1.02, 1.27]
9.1.3 Easy	1	596	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.85, 0.94]
9.1.4 No restriction by intravenous access difficulty level	2	390	Risk Ratio (M‐H, Random, 95% CI)	1.20 [1.09, 1.33]
9.2 Overall success of cannulation	8	728	Risk Ratio (M‐H, Random, 95% CI)	1.13 [1.00, 1.27]
9.2.1 Difficult	7	428	Risk Ratio (M‐H, Random, 95% CI)	1.19 [0.98, 1.45]
9.2.2 No restriction by intravenous access difficulty level	1	300	Risk Ratio (M‐H, Random, 95% CI)	1.10 [1.03, 1.18]
9.3 Pain	5	1260	Mean Difference (IV, Random, 95% CI)	0.38 [0.08, 0.68]
9.3.1 Difficult	3	263	Mean Difference (IV, Random, 95% CI)	0.23 [‐0.42, 0.88]
9.3.2 Moderate	1	401	Mean Difference (IV, Random, 95% CI)	0.10 [‐0.47, 0.67]
9.3.3 Easy	1	596	Mean Difference (IV, Random, 95% CI)	0.60 [0.17, 1.03]
9.4 Procedure time for first‐pass cannulation	6	1564	Mean Difference (IV, Random, 95% CI)	61.44 [10.40, 112.49]
9.4.1 Difficult	2	219	Mean Difference (IV, Random, 95% CI)	119.85 [88.64, 151.05]
9.4.2 Moderate	1	401	Mean Difference (IV, Random, 95% CI)	95.20 [72.77, 117.63]
9.4.3 Easy	1	596	Mean Difference (IV, Random, 95% CI)	94.80 [81.15, 108.45]
9.4.4 No restriction by intravenous access difficulty level	2	348	Mean Difference (IV, Random, 95% CI)	‐11.31 [‐58.36, 35.74]
9.5 Procedure time for overall cannulation	9	743	Mean Difference (IV, Random, 95% CI)	‐14.82 [‐100.35, 70.72]
9.5.1 Difficult	7	353	Mean Difference (IV, Random, 95% CI)	97.47 [‐17.58, 212.52]
9.5.2 No restriction by intravenous access difficulty level	2	390	Mean Difference (IV, Random, 95% CI)	‐77.42 [‐185.70, 30.86]
9.6 Number of cannulation attempts	8	748	Mean Difference (IV, Random, 95% CI)	‐0.29 [‐0.43, ‐0.15]
9.6.1 Difficult	7	448	Mean Difference (IV, Random, 95% CI)	‐0.17 [‐0.36, 0.03]
9.6.2 No restriction by intravenous access difficulty level	1	300	Mean Difference (IV, Random, 95% CI)	‐0.40 [‐0.59, ‐0.21]
9.7 Patient satisfaction	5	363	Std. Mean Difference (IV, Random, 95% CI)	0.17 [‐0.10, 0.44]
9.7.1 Difficult	4	273	Std. Mean Difference (IV, Random, 95% CI)	0.25 [0.01, 0.50]
9.7.2 No restriction by intravenous access difficulty level	1	90	Std. Mean Difference (IV, Random, 95% CI)	‐0.19 [‐0.60, 0.23]
9.8 Overall complications	7	1698	Risk Ratio (M‐H, Random, 95% CI)	0.80 [0.45, 1.43]
9.8.1 Difficult	3	311	Risk Ratio (M‐H, Random, 95% CI)	0.76 [0.29, 1.96]
9.8.2 Moderate	1	401	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.38, 1.82]
9.8.3 Easy	1	596	Risk Ratio (M‐H, Random, 95% CI)	2.48 [0.90, 6.87]
9.8.4 No restriction by intravenous access difficulty level	2	390	Risk Ratio (M‐H, Random, 95% CI)	0.48 [0.24, 0.96]