It results from
variation in sample sizes, baseline characteristics of the
populations, study protocols and defi nitions used,
diagnostic criteria, and study outcomes (positive or
negative). Furthermore, substantial clinical heterogeneity
can be expected with regard to associated prevention
measures. In the selected studies, information about
prevention of ventilator-associated pneumonia—other
than oral care—was rather scarce or absent. Besides,
heterogeneity was also identifi ed within studies, since
diff erent frequencies of care or combinations of
interventions were applied.1