A placebo-controlled, parallel, prospective trial was conducted. The patients were children from 1 to 12 years of age Living in the metropolitan area of Chihuahua City, Chihuahua State, Mexico. The families were cared for under the state (Pensiones Civiles de Chihuahua, free medical services for workers of state government).
An upper ARTI was defined as the presence of at least one of the following signs: rhinorrhea; sore throat or cough, without signs of lower ARTI, for > 48 h. Lower ARTI was defined as the presence of at least one of the following signs: rales or crepitations, wheezing, stridor, respiratory rate > 50/min, cyanosis, or chest indrawing for > 48 h. Otitis was defined as acute onset of earache with erythema and limited mobility of the tympanic membrane determined by pneumatic otoscopy. Similar upper and lower ARTI definitions have been used in epidemiologic studies in developing countries. canadian neightbor pharmacy
In a previous clinical trial in Mexico, the placebo group presented 2.99 ± 0.81 ARTIs in 6 months; therefore, we projected about 6 ± 1.6 ARTIs in a 12-month period, and a 50% reduction in the incidence of ARTI according to previous trials in Mexico. Considering a difference of 3.0 ± 3.0 ARTIs between the groups during 12 months, the calculated sample size by group was 23, as calculated by software (Primer on Statistics 3.0; Mc-Graw-Hffl; New York, NY).
The selection criteria were as follows: at least three ARTIs registered on clinical files of the social security system during the previous 6 months; negative familial history of allergy; no seasonal or food-related wheezing and nasal itchiness; absence of nasal folds, with no anatomic alterations of the respiratory tract by physical examination; chronic respiratory diseases (tuberculosis, cystic fibrosis); autoimmune diseases; liver failure; kidney failure, malnutrition, or cancer; and no treatment with corticosteroids, immunosuppressants, immunostimulants, 7-globulins, or anticonvulsive drugs in the last 6 months.
Informed consent for each participant was obtained from the parents at entry. Children > 3 years old gave their oral consent. The protocol and case report form were approved by the local committee of investigation and ethics and were performed according to the Mexican regulation and the Helsinki Declaration of 1975, as revised in 1983.