Sample size was calculated based on results obtained in earlier publication.[8 (link)] Minimum sample size required for the case group was 17 and for the control group was 68, with a total of 85.
Statistical analysis was performed using the SPSS program for Windows, version 17.0 (SPSS Inc., Chicago, Illinois, USA). Chi-square test was used for comparisons between the study groups with respect to percentage. P < 0.05 was considered statistically significant.