2.6. Statistical analysis
Statistical analyses were performed using SPSS version 23 (IBM Corp. in
Armonk, NY). There was no missing data of the variables of interest for
the patients included in the study. Shapiro-Wilk test was used to
evaluate the distribution of the data. Descriptive data are present as
the median with the interquartile range (IQR) for non-normally
distributed numerical variables, and the frequency (n) and the
percentage (%) for categorical variables. The Mann–Whitney U test was
used for comparing non-normally distributed data between two study
groups. Pearson Chi-square test was used for comparing categorical
variables. The recurrence risk was determined by univariate and four
multivariate logistic regression models that were developed to estimate
the recurrence risk using the demographics, baseline characteristics,
perioperative characteristics and presence of postoperative complication
as potential confounders. In the model 1, age and sex were included; in
the model 2, sinus type and number of orifices were included in addition
to variables of model 1; in the model 3, duration of surgery, length of
stay and wound healing time were included in addition to variables of
model 2; in the model 4, presence of any type of complication was
included in addition to variables of model 3. The Odds Ratios (ORs) with
95% confidence intervals (CIs) were assessed for comparing recurrence
risk between surgical procedures. p <0.05 was considered
as statistically significant level.