Objectives: To evaluate the accuracy of Tanner-Whitehouse method (TW3 RUS score) on Thai subjects.
Methods: A total of 200 hand and wrist radiographs from patients who need orthodontic treatment or other treatments were collected at the Department of Radiology, Faculty of Dentistry, Chulalongkorn University. The subjects, defined as contemporary Thais, were 8-20 years old when the radiographs were taken. Age estimation was done using Tanner- Whitehouse 3, RUS score, method (TW3-RUS) by two calibrated observers. The observation was done twice with 4-week-time interval. Comparison between the chronological ages and the estimated ages by TW3-RUS method was done. Descriptive analysis was analyzed. Mean differences between the age estimated by TW3-RUS method and the chronological age were calculated. Wilcoxon signed ranks test and Spearman’s correlation coefficient were used to compare the estimated age with the chronological age. Weighted kappa analysis was used to test the intra-observer and inter-observer reliability.
Results: The mean difference between the estimated age and the chronological age showed an overall overestimation of 0.15 (standard deviation (SD) = 1.63) year. Wilcoxon signed ranks test showed statistically significant difference between the TW3-RUS estimated age and the chronological age (p = 0.02). Spearman’s correlation coefficient showed significant correlation between the TW3-RUS estimated age and the chronological age (rs = 0.86, p < 0.001). Good intra-observer reliability was found with weighted kappa of 0.813 - 0.941. Moderate to good inter-observer reliability was found with weighted kappa 0.674 - 0.946. Ulna bone showed the lowest inter-observer reliability (kappa value = 0.674).
Conclusion: Significant differences were found between the estimated age using TW3-RUS method and the chronological age of a group of contemporary Thai children and adolescents. Further studies should be conducted on the adaptation of TW3-RUS method in order to improve its accuracy on Thai population.