 Power calculation A power calculation of the clinical scores with alpha set at 0.05 and beta 0.2 estimates that 85 subjects in each arm is needed to disclose a 30 difference between the treatment groups with respect to the clinical scores Fleiss Statistical Methods for rates and Proportions, 2nd edition, John Wiley and Sons New York 1981. Due to expected relocations and failure to comply with the protocol, the goal will be to recruit a minimum of 220 and a maximum of 250 children. 