Statistical analysis
Data were recorded in Excel v15.0 and analyzed using IBM SPSS
Statistical package, v. 24. Normal goodness of fit was evaluated using
the Kolmogorov–Smirnov test. The nonparametric data are expressed as
median (Mdn) and interquartile range (IQR 25%–75%). For the
nonparametric contrast of 2 unrelated samples, the Mann–Whitney U test
was used. Relative risk computed as
Iexposed/Iunexposed(Ie/Iu) was used as an association
measure. Rosenthal’s r calculated from Wilcoxon Z values (r = Z/N root),
attributable risk (AR) as the difference between the incidence of
disease in the exposed population versus incidence in the unexposed
population, calculated as Ie-Iu, attributable fraction among the
exposed (AFe) as the proportion of incidents in the exposed group that
are attributable to the risk factor calculated as (Ie-Iu)/Ie and
population-attributable fraction (PAF) the percentage of cases in the
entire study population that can be attributed to the exposure
calculated as (PAF) = (proportion of cases exposed x AFe) were used for
impact measurement or effect size. To analyze the association among
qualitative variables, the chi-squared test was used. Statistical
significance was set at p <0.05.