Is single-injection digital nerve block (SDNB) associated with a lower invalid anesthesia rate than two-injection digital nerve block (TDNB) for patients with traumatic digital lacerations? – An Update

Objective: To test whether selection bias has affected the reported effect estimate for SDNB to reduce the invalid anesthesia for patients with traumatic digital lacerations in comparison to TDNB (RD –0.04. 95%CI: -0.23 to 0.15). Method: Trial adjusted, simulated comparator trial (SCT) based I2 test for single randomised controlled trials using revised I2 threshold limits. Result: A baseline covariate imbalance, either due to chance or due to selection bias was established, being equivalent to selection bias level = B% 0-30 (Bias category = 1). This level suggests that 0-30% of (0 – 15 of the total 50) subjects were non-randomly allocated in favour of one treatment group above the other. Conclusion: The effect estimate reported by the tested trial does not suggest any significant differences between both types of procedure in reducing the invalid anesthesia rate. The selection bias level, estimated by use of the trial adjusted, simulated comparator trial (SCT) based I2 test for single RCTs, B% = 0-30, appears to be not high enough in order to have affected the reported estimate. In line with new findings, this report updates previous report to the same RCT: EBSM Volume 2, Issue 1, 2026 Pages 23-26, DOI: 10.5281/zenodo.17760867.