Accuracy of radiologically based growth prediction in adolescents

Objectives: Methods to predict the final height of adolescents are commonly used in clinical practice. Different formulas based upon auxiological parameters and radiological assessments of bone maturity have been developed more than 30 years ago. Aim of our study was to evaluate the accuracy of the height predictions performed in our outpatient clinics.

Methods: We report on 52 patients (36 boys and 16 girls, age 8 to 17 years) which presented between 11/93 and 7/05 for final height estimation and had no evidence of malnutrition, systemic disease or GH deficiency. The prediction of final height was calculated according to the formula of Roche, Wainer and Thissen (RWT), which involves bone age, height and weight of the patient and mid-parenteral height. An additional estimation according to Bayley and Pinneau (BP) was performed (based only on biological and skeletal age and current height). The final height of these patients (now aged 16 to 26) was ascertained between 7/06 and 10/06 and compared to the predicted data.

Results: According to RWT the mean deviation of the final height compared to the predicted amounted to 1.9% with a difference in height of 3.8cm for girls and 3.3cm for boys. The mean BP predicted height erred by 2.2% (difference of 4.7cm for girls and 3.4cm for boys). In 33% of the patients the final height was overpredicted by RWT, in 45% by BP. In 51% (RWT) and 44% (BP), respectively, the patients' final height showed an under-prediction. Of note was that applying BP the girls' final hight tended to be overestimated, whereas the boys tended to exceed the predicted values. This gender specific difference was not found applying RWT.

Conclusion: Although the formulas commonly used for prediction of final height were generated many decades ago they still provide results within clinically acceptable error limits. Yet there is some evidence that in the formula according to BP gender specific coefficients might need to be slightly adapted. Overall the accuracy of the calculations by the method of RWT seems to be superior to BP.