Statistical analysis The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows). All quantitative variables were estimated using measures of central location (mean, median) and measures of dispersion (standard deviation and standard error). Normality of data was checked by measures of skewness and Kolmogorov Smirnov tests of normality. For normally distributed data means were compared using student's t-test for two groups. For more than two groups ANOVA was applied. For Skewed data Mann-Whitney test was applied. Qualitative or categorical variables were described as frequencies and proportions. Proportions were compared using Chi square test. Sensitivity, specificity and diagnostic accuracy of different methods was calculated. All statistical tests were two-sided and were performed at a significance level of α=.05.