Height as a proxy for weight in determining azithromycin treatment for paediatric trachoma

Azithromycin (Zithromax, Pfizer Inc., New York, NY, USA) is effective in the control of blinding trachoma. Community-based azithromycin treatment is recommended by the World Health Organization as part of a multipronged strategy aimed at the global elimination of binding trachoma by the year 2020. Paediatric trachoma is treated with azithromycin according to weight at a target dosage of 20 mg/kg. However, conventional weight-based treatment may be problematic in the field due to the logistical difficulties associated with weight scales. We assessed the accuracy of using height as a proxy for weight to determine azithromycin treatment in 4 countries--Viet Nam, Tanzania, Ghana, and Mali--where mass treatment programmes are underway. Population-based data collected from 1988 to 2000 were analysed using least squares regression. Height treatment schedules were developed for each data set. The accuracy of each schedule was evaluated according to the percentage of children receiving treatment within a dosage range of 20-30 mg/kg, a conservative estimate of the safe and effective treatment range for paediatric trachoma. Using height to determine dose, 89-95% of children would receive a dosage of 20-30 mg/kg. In these populations, height-based treatment is a reliable alternative to conventional weight-based treatment. Methods for developing height schedules presented in this analysis could be applied to other regions and therapeutics.