Network meta-analysis
Odds ratios (ORs) were used for the early outcome and were calculated by extracting the raw data from the studies. NMA was performed using the frequentist method (generic inverse variance method) with the ‘netmeta’ statistical package in R (version 4.0.5., R Project for Statistical Computing), as described by Rücker et al 14. Random effect network meta-analyses were performed to make direct and indirect comparisons of two- and three-arm studies comparing different levels of hypothermia in aortic arch surgery 15. Inconsistency in NMA was evaluated by conducting conventional pairwise meta-analyses and comparing direct and indirect OR, also called node-splitting. Additionally, quadratic net heat plots were computed to investigate inconsistency. Heterogeneity was reported as low (I2=0–25%), moderate (I2=26–50%), or high (I2>50%).