4.5. Statistical Analysis

Continuous data were expressed as median and interquartile range (IQR), and categorical variables were presented as counts or percentages. Univariate analysis between beta-lactam treatment courses attaining an early optimal vs. quasi-optimal/suboptimal PK/PD target was performed by means of Fisher’s exact test or the chi-squared test (for categorical variables), or the Mann-Whitney U test (for continuous variables). Multivariate logistic regression analysis was implemented for testing possible variables associated with a failure in attaining early optimal PK/PD targets. Independent covariates with a p value < 0.10 in the univariate analysis were included in the multivariate logistic regression model. Statistical significance was defined as a p value < 0.05. Statistical analysis was performed by using MedCalc for Windows (MedCalc statistical software, version 19.6.1, MedCalc Software Ltd., Ostend, Belgium).