The Validity of Iscan’s Age Estimation Method applied to the Fourth Rib in a Thai Male population

Abstract Iscan’s staging method for age estimation from fourth ribs has been proved to be a potentially useful tool for various populations. However, due to interracial variations, it is necessary to calibrate its’ accuracy in reference to a population of Thai males before it can be applied. This study aimed to evaluate the validity of phasing analyses of sternal ends of fourth ribs developed by Iscan, et al., on a Thai male population. The Iscan’s method was applied to 50 Thai males aged 18 years and above. Staging of sternal ends of the ribs was analyzed based on 3 morphological features: pit depth, pit shape, and rim and wall configurations – designated as components 1, 2, and 3, respectively. The data was analyzed using descriptive statistics, one-way ANOVA, and cross-tabulation with Kendall’s Tau-c correlation. It was found that sternal end stages of fourth ribs in each component, inclusive of composite scores, are positively correlated to the age of the individual (P < 0.001). However, Iscan’s result - which was derived from a population of white males - delivers age-underestimation in a Thai population. Hence, we developed a modified age prediction reference table for application to Thai males. Applying cross-tabulation analysis, stages 1 and 2 were found only in individuals who were less than 40 years old, and stages 4 and 5 were found only in the 40 years and above age-group except for 1 case. Keywords: Age estimation, Fourth rib, Iscan’s method, Thai male