5. Chronic inflammation states, such as recurrent pharyngitis, may result in an increased propensity toward bleeding, and thus subjects with this potential confounder are excluded. Children with 3 or more acute pharyngitis episodes within the past year are excluded. A pharyngitis episode is defined as documentation by physician of the episode and >1 of the following: oral >38.3 degrees C, lymphadenopathy >2cm or tender lymphadenopathy, tonsil/pharyngeal exudates, group A beta hemolytic streptococcus positive, or antibiotic administration for proved/suspected streptococcal infection.