CORR Insights^®: Paley’s Multiplier Method Does Not Accurately Predict Adult Height in Children with Bone Sarcoma

Where Are We Now?

Gilg and colleagues discussed the reliability of Paley’s multiplier method in predicting adult height in patients with osteosarcoma and Ewing’s sarcoma, the influence of chemotherapy on growth velocity, and the effect of these diseases on the final adult height on patients. The retrospective study included patients diagnosed with either disease before they reached skeletal maturity. Researchers recorded followup data on the patients until they reached the age of 18, and used patient records or patient phone conversations to collect initial and final heights. Gilg and colleagues used the multiplier method to compute the predicted height of the study patients, and then compared the predicted height to the actual adult height. According to results of the study, the Paley multiplier method overestimated adult height in 76% of the patients, and the mean predicted height was 2.3 cm greater than the adult height. Therefore, they concluded, the Paley method is not an accurate predictor of adult height for patients who have bone sarcoma.

Anderson and Green [3] have postulated that the use of skeletal age is superior to chronological age in predicting lower extremity growth. Paley and his colleagues developed the multiplier method which used only chronological age. Comparison of the two methods found that although the Paley method predicted adult height more accurately across all ages, skeletal-maturity determinations were better at predicting mature limb length during adolescence [8].

Where Do We Need To Go?

Determining bone age, and ultimately final adult height, is problematic. The manual rating methods, which Thodberg et al. [9] divided into the holistic Greulich and Pyle method and analytical methods including the Tanner Whitehouse and the Fels methods, are subject to low inter and intrarater variability. The Greulich and Pyle method relies heavily on rater experience and intuition. The Tanner and Whitehouse method is an example of an analytical method, which relies on a sequence of image examples and line drawings, and the rater is expected to use abstract reasoning to deduce the maturity stage of the child. This led to the development of a computerized bone aging method by Tanner and colleagues [9].

A recent review by Lee et al. [6] also evaluated the accuracy of four different methods for predicting amount of growth remaining, and therefore, the correct timing of epiphysiodesis. The review compared Moseley’s straight line graph, the Green-Anderson growth remaining method, Paley’s multiplier method using skeletal age, and Paley’s multiplier method using chronological age. Results showed that none of these studies generated precise predictions of final adult leg length discrepancy.

The results of the present study are similar to that of Aguilar et al. [1, 2], who noted that the multiplier method erred as much as 4.4 cm when predicting adult heights for boys and 2.6-cm for girls 5-years-old and younger. Another study by Sanders et al. [8] showed that use of the multiplier method can cause errors as great as 5 cm when used in patients who already had their growth spurt. These data support the hypothesis that chronological age may be more accurate in predicting final height for preadolescents, and that skeletal age may be more accurate for adolescents. It may be prudent to consider that these two groups are different, and that two different methods therefore should be used.

How Do We Get There?

There have been numerous comparisons of the various methods of predicting height for different conditions such as constitutional tall stature, hypothyroidism, constitutional short stature, and achondroplasia [4, 5, 7]. The present study is the only one to use these methods for patients who had limb salvage surgery for primary bone tumors. Instead of just limiting investigations to just the multiplier method, it may be beneficial to also compare others that use chronological age to those that use skeletal age. The physeal status suppressed by tumor, chemotherapy, radiation, and metabolic status should be under consideration. Instead of applying one single method to both adolescents and preadolescents, we can also try to compare the accuracy of the different methods to either group, to determine which is best or most accurate for each.