It Is Time to Abandon the Use of Body Surface Area Derived From a 100-Year-Old Formula

Clinical parameters and drug dosing indexed to body surface area (BSA) have been widely used. For example, cardiologists use indexation to BSA for the cardiac linear measurements, aortic valve area (AVA), stroke volume, left ventricular mass, and so on; oncologists use BSA indexed dosing for chemotherapeutic agents; nephrologists use indexation of renal function parameters to BSA. BSA is calculated by the 2 most commonly used formulas, Du Bois or Mosteller. However, despite its wide use, little attention was paid to the accuracy and validation of the calculated BSA. The classic Du Bois formula, BSA(m²) = Weight (kg)^0.425  × height (cm)^0.725  × 0.007184, was developed in 1916 and has been considered the gold standard. The equation is derived from the direct tape measurements of only 9 patients. Its validation with the direct tape measurement of BSA was done in only 17 cadavers. Mosteller further developed a simplified formula in 1987, BSA (m²) = ([Height (cm) × Weight (kg)] / 3600)^½, which is the most commonly used in the United States due to its simplicity. The Mosteller formula was only validated by the correlation with the Du Bois equation. Du Bois was found to overestimate the BSA by more than 15% when compared with the direct measurements of BSA of 401 individuals, especially in patients who are obese. Furthermore, Mosteller BSA is 5% higher in female and 3% higher in male patients than the BSA from the Du Bois formula. This implies that the BSA calculated from Mosteller formula could overestimate BSA by 20%. The clinical impact of BSA overestimation has not been directly studied. Here I have summarized some indirect evidence to illustrate the impact by using 2 BSA indexation approaches, aortic valve stenosis and anthracycline dosing, as I practice in both cardiac imaging and cardio-oncology.

To read this article in its entirety, please visit our website.