Variability in determination of body weight used for dosing busulphan and cyclophosphamide in adult patients: results of an international survey.

Fifty-two BMT institutions were sent a questionnaire asking for details of dosing for busulphan, cyclophosphamide (bu-cy), cyclosporin and methotrexate (CSA-MTX). The following data were requested: (a) the method used to determine the body weight for dosage calculations (b) the actual dose per weight and (c) the schedule of administration. Thirty-six (69%) institutions responded and 33 were evaluable. There was substantial variation in the method used to determine weight for bu-cy. No single method was used in more than 30% of units, although most units made some allowance for discrepancies between actual and ideal body weight. There was more uniformity in the method of weight determination for CSA-MTX, with the majority of units using actual body weight. Conversely, there was much more variation in the dose per weight formulae and schedules used for CSA-MTX than for bu-cy. These substantial differences highlight the importance of specifying these criteria when the toxicity and efficacy of chemotherapy regimens is reported and the need for further studies to determine the optimal weight formulae for dosage calculations.