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%).