2.6 Statistical analyses:
Shapiro-Wilk tests were used to assess data normality. Maternal GCF-PLAP
concentrations were not normally distributed; therefore, non-parametric
tests were used to assess statistical differences. Comparisons between
proportions were performed with a chi-squared or Fisher’s exact test,
and the Mann-Whitney U test was used to compare continuous variables.
The association strength was assessed by using a multiple logistic
regression model, which was adjusted by systolic blood pressure and
PLAP-GCF concentrations. Receiver Operating Characteristic (ROC) curves
summarized the classification performance of biomarkers. Goodness of fit
and internal validation of the model were assessed using the Bayesian
Information Criterion (BIC) and bootstrapping. The statistical analysis
was performed using a commercially available software package (STATA
software, StataCorp version 14.1, Lakeway Drive College Station, TX,
USA). A p < 0.05 was considered statistically significant.