Comparison of two different formulas for body surface area in adults at extremes of height and weight

Background Different equations for predicting body surface area have been derived. The DuBois and Mosteller body surface area equations are considered equivalent, but the accuracy in adult patients at extremes of height and weight is unknown. Purpose To compare body surface area in patients at extremes of height and weight using both formulas to determine whether a difference affected chemotherapy dose. Methods Anthropometric data were extracted from the 2012 Centers for Disease Control and Prevention Vital and Health Statistics. Data for both males and females were examined. The 50th percentiles of weight and height were used to calculate the body surface area with both formulas. Calculations were repeated using the 5th through 95th percentiles for weight, then the 5th through 95th percentiles for height, and so forth until all extremes of height and weight were examined. Each body surface area was used to calculate a chemotherapy dose. A difference of ≥4.5% in dose was considered clinically significant. Results Differences were apparent in both males and females. Dosing differences were most apparent in patients in the 50th, 75th or 95th percentile for both height and weight. Differences are also noted in other percentiles, suggesting that patients of smaller stature may also be affected. Conclusion Guidelines recommend full doses of chemotherapy for patients with curative intent but do not specify which body surface area formula is preferred. Our results imply that the Mosteller equation provides a greater chemotherapy dose, and this difference may be clinically significant in patients who are in the 50th to 95th percentiles for height, weight or both. Further study is necessary to validate these results and determine the impact on patient outcomes.