RESUMO
Objective To determine the correlation and agreement of sacral ratio(SR)measured by lateral and anteroposterior radiographs in patients with anorectal malformation(ARM).Methods A retrospective analysis was conducted on the anteroposterior and lateral radiographs images of the sacral vertebrae of patients with ARM.All SR values were measured by three radiologists.Pearson's correlation coefficient were used to assess the correlation between the SR measured by lateral and anteroposterior radiographs.A weighted Kappa statistic was used to measure the agreement between how the anteroposterior and lateral SR categorized observations into risk groups.Results Of the 385 ARM patients,25 patients whose radiographs image quality was insufficient to calculate SR value were excluded.For a given pair of measurements,the mean lateral SR value was 0.08 units greater than the anteroposterior SR value[95%confidence interval(CI)0.06-0.09,P<0.01].Anteroposterior and lateral images had a moderate positive correlation(r=0.79,95%CI 0.73-0.79,P<0.01)and moderate agreement in risk categorization(Kappa=0.62,P<0.01).Anteroposterior and lateral readings conducted by all three radiologists had excellent inter-rater reliability with intraclass correlation coefficient(ICC)for anteroposterior and lateral SR of 0.88 and 0.84,respectively.Conclusion Even though the anteroposterior and lateral SR values have moderate positive correlation,the mean SR value determined by images in the lateral is 0.08 units greater than the anteroposterior.Anteroposterior and lateral SR value conclude different risk categories relatively often.The SR values measured by lateral sacral radiographs are more clinically significant than those measured by anteroposterior radiographs.