2.3. Statistical Analysis
Chi-square test of homogeneity (Rx2) was performed to determine if the proportions of pneumatized and non-pneumatized petrous apex and perilabyrinthine cells and the proportions of fully pneumatized, diploic and sclerotic mastoid cells were statistically significantly different between healthy and diseased-side for group 1 and group 2.
The assumption of normality for volumes of paranasal sinuses was not satisfied with the healthy-side and diseased-side of group 1 and group 2, as assessed by Shapiro-Wilk’s test. (p<0.05) Therefore, A Mann-Whitney U test (as a non-parametric test) was run to determine if there were differences in volumes of paranasal sinuses between healthy-side and diseased-side for group 1 and group 2. Kruskal Wallis H test was performed to compare the paranasal sinus volumes between the related ears with grouped based on their mastoid pneumatization. Dunn’s procedure was performed, and adjusted p-value (Bonferroni correction) was calculated for posthoc analysis.
Statistical significance was accepted at p< 0.05.
Results
A total of 179 patients were screened. Thirty-one patients were excluded due to age, 35 due to bilateral ear disease, 7 due to insufficient HRCT images, and 5 due to sinonasal disease. Remaining 101 patients were included in statistical analysis.
Group 1, COM with isolated tympanic membrane perforation, consists of 51 patients, of which 26 (51%) were female and 25 (49%) male. The average age was 37.1(± 14.75).
Group 2, COM with cholesteatoma/retraction pocket, consists of 50 patients, of which 27 (54%) were female and 23 (46%) male. The average age was 38.8 (±13.73).