Tanner's Target Height Formula Underestimates Final Height in Asian Indians – A Cross-sectional Observational Study

INTRODUCTION: Target height (TH) calculation by Tanner's formula has been shown to be inaccurate in many countries However, there is no published data on the accuracy of TH calculation by Tanner's formula in Indians. Hence, this study was conducted to assess whether Tanner's TH formula is an accurate tool to predict final height in Asian Indian population and to identify new TH formulae or models to better fit Indian population. MATERIAL AND METHODS: This is a cross-sectional, questionnaire-based study conducted in a tertiary care hospital from South India. A total of 396 questionnaires were randomly distributed to undergraduate medical students who were instructed beforehand to get their heights and heights of their parents and siblings between the age of 18 to 24 years of age measured by a nearby pediatrician. From 396 questionnaires, data of 481 young adults and their parents were obtained. Target height was calculated by Tanner's formula and compared with attained height. RESULTS: The study comprised of 197 males and 284 females. Sons and daughters were 2.34 ± 7.19 cm and 1.58 ± 5.68 cm taller than TH. Son's height had best correlation with TH (r = 0.408), whereas daughter's height had best correlation with maternal height (r = 0.560). Both males (0.263 vs 0.365) and females (0.319 vs 0.560) had relatively weaker correlation with paternal heights than maternal heights. Target height explained 29.7% and 16.7% of variance in daughter's and son's height, respectively. Using the parental heights as variables, multiple regression yielded 50.03 + 0.172 (father's height) +0.510 (mother's height) and 74.09 + 0.236 (father's height) +0.377 (mother's height) as the best models to predict daughter's and son's height, respectively. CONCLUSION: Our study suggests that Tanner's TH formula underestimates final attainable height in Asian Indians.