Effect of knowledge of chronologic age on the variability of pediatric bone age determined using the Greulich and Pyle standards

OBJECTIVE. The purpose of this study was to investigate the impact of knowi ng chronologic age on the variability of pediatric bone age determination u sing the method of Greulich and Pyle. MATERIALS AND METHODS. Radiographs of the left hand of 107 patients were in terpreted by four radiologists on two separate occasions, once with and onc e without knowledge of the patient's chronologic age at time of interpretat ion. Twenty-five radiographs were randomly selected and reevaluated twice b y each radiologist. Interobserver and intraobserver variability were calcul ated and compared for the two conditions. The distribution of studies with normal and abnormal findings was then compared across knowledge conditions for all observers and by individual observer, using two standard deviations above and below chronologic age as the range of "normal." RESULTS. When the chronologic age was known, the interobserver reliability coefficient for knowledge of chronologic age was 0.954 and when not known, 0.952. The intraobserver reliability coefficients when chronologic age was known ranged from 0.944 to 0.967, and when not known from 0.938 to 0.980. O bservers interpreted 58% (248/428) of the radiographs as having normal find ings when chronologic age was known and 48% (205/428) when chronologic age was not known. CONCLUSION. Knowing chronologic age before assessing bone age radiographs d oes not affect the reproducibility of assessment. However, observers are mo re likely to interpret the radiograph as showing normal findings when chron ologic age is known than if the interpretation is performed with the observ er unaware of chronologic age.