Standardization of body surface area calculations

Purpose. Antineoplastic agents have a narrow therapeutic index and therefore require the greatest degree of dose individualization. In choosing a body surface area (BSA) for‘mula, the challenge remains in obtaining consensus among prescribers. The objective of this review is to assess the various formulae available for calculating BSA and to adopt a standard formula within an institution.

Methods. Retrospective review of medication orders containing the patient’s height and weight as well as BSA calculated by the outpatient clinic staff within the Cross Cancer Institute (CCI) from 7 to 15 July 1998. Four BSA calculating devices, in current use by the clinical staff, were also tested to determine the formula currently utilized by prescribers.

Results. Thirty-three orders sent to the pharmacy containing the patient’s height, weight, and BSA were reviewed. Ninety-four per cent of the BSA calculated by the clinic staff differed from pharmacy’s calculations by 0% to 4%. One BSA calculation differed by 8% and another differed by 14%. With respect to the available BSA calculating devices, all appeared to be based on the Du Bois formula.

Conclusion. Of the various formulae available for estimating BSA, we concluded that the Mosteller equation is the most acceptable based on both BSA calculation accuracy and ease of use. Based on this determination, the CCI approved the adoption of the Mosteller equation as the institutional standard. This equation was later standardized throughout the entire Alberta Cancer Board. Other methods of dose determination are emerging, including therapeutic drug monitoring and PMT dosing. Further investigation is required as to whether these methods will lead to better standardization of dose.