This study
is limited, however, by the clinical and statistical
heterogeneity between the trials included. Although this
lack of homogeneity was clinically perceived as
substantial, statistically it was moderate in the overall
meta-analysis (I²=38%), and no evidence of heterogeneity
(I²=0%) was reported in the subanalyses of studies on
cardiosurgical patients (fi gure 4), and those assessing
chlorhexidine at concentrations of 0·12% and 2%
(fi gure 3). Heterogeneity is an inherent problem in
systematic reviews and meta-analyses.3