Statistical analysis
Data are expressed as median and interquartile range
(IQR), unless indicated otherwise. Data concerning infections
in previous years showed that 50% of VLBW infants
developed a nosocomial bloodstream infection. A sample
size of approximately 180 infants per period would be
required to detect a 30% reduction in the incidence of
nosocomial bloodstream infection (80% power with 5%
two-sided significance). Differences in frequencies of
various findings between groups were analyzed by the
Fisher’s exact test or Pearson chi-square. As the drying
time for the four hand hygiene observation periods showed
skewed distribution, differences were analyzed by an
ANOVA after log-transformation. This analysis pertained
only to those healthcare professionals who performed
hand hygiene practices.