2. Sensitivity analysis for difficult participants.
| Outcomes | Original results | RCTs only | Low ROB studies only | |
| First‐pass success of cannulation | ES | 1.50 (1.15, 1.95) | 1.50 (1.15, 1.96) | 1.82 (0.98, 3.37) |
| I2 | 62% | 66% | 65% | |
| Overall success of cannulation | ES | 1.40 (1.10, 1.77) | 1.19 (0.98, 1.45) | 1.03 (0.92, 1.16) |
| I2 | 88% | 79% | NA *1 | |
| Pain | ES | ‐0.20 (‐1.13, 0.72) | 0.23 (‐0.42, 0.88) | 0.20 (‐0.61, 1.01) |
| I2 | 62% | 0% | NA *1 | |
| Procedure time for first‐pass cannulation | ES | 119.9 (88.6, 151.1) | 119.9 (88.6, 151.1) | 120.6 (88.3, 152.9) |
| I2 | 0% | 0% | NA *1 | |
| Procedure time for overall cannulation | ES | ‐24.9 (‐323.1, 273.3) | 97.5 (‐17.6, 212.5) | NA *2 |
| I2 | 77% | 0% | NA *2 | |
| Number of cannulation attempts | ES | ‐0.33 (‐0.64, ‐0.02) | ‐0.17 (‐0.36, 0.03) | ‐0.60 (‐1.51, 0.31) |
| I2 | 64% | 0% | NA *1 | |
| Patient satisfaction | ES | 0.49 (0.07, 0.92) | 0.25 (0.01, 0.50) | NA *2 |
| I2 | 71% | 5% | NA *2 | |
| Overall complications | ES | 0.64 (0.37, 1.10) | 0.76 (0.29, 1.96) | 0.77 (0.21, 2.77) |
| I2 | 0% | 0% | NA | |
Dichotomous outcomes shown as RR (95% CI), continuous outcomes as MD or SMD (95% CI) ES: effect size; MD: mean difference; NA: not applicable; RCT: randomised controlled trial; ROB: risk of bias; RR: risk ratio; SMD: standardised mean difference *1: only one study; *2: no study