The design was a prospective multicentric observational study, including

medical institutions located in six cities of Colombia (Bogotá, Cali, Medellín, Barranquilla, Bucaramanga and Pereira), lasting one calendar year (April 2005–April 2006). The selected institutions were characterized by reporting between 1000-2000 pediatric selleck compound visits monthly and 100-200 hospitalizations for LRTI in infants of one year of age or less. Given previous reports of RSV positivity on around 50.0% of patients hospitalized for LRTI in Colombia, we calculated a minimum sample size of 500 patients of one year or less hospitalized with suspicion of RSV LRTI. The total number of patients included in the study was 717 and met the following inclusion criteria: 1) to be one year of age or less 2) to have visited the emergency department and been hospitalized for suspicion of LRTI (diagnosis of bronchiolitis, pneumonia, or bronchopneumonia). After the patients were hospitalized, the presence or absence of RSV was confirmed by performing a rapid immunofluorescence test in nasopharyngeal secretion (Clearview RSV antigen detection

test). The reported test sensitivity was 95.2%, specificity 99.3%, PPV 95.2% and NPV of 99.3%.13 The results of the test were verified through an enzyme immunoassay (Directigen RSV), Forskolin performed in one of the institutions participating in the study (Clinic of the Americas, Medellín).13 Risk factors such as gestational age less than 32 weeks at birth, Methane monooxygenase and chronic lung disease were determined. Clinical outcomes such as average hospital stay, admission to the pediatric intensive care unit,

mechanical ventilation requirement, and mortality were assessed in high-risk patients. RSV positive and negative groups were compared. All the protocols and informed consent were reviewed and approved by the ethics committee of each institution. A descriptive analysis of the population was conducted. Incidence of patients with confirmed RSV LRTI was calculated by trimester and city. RSV positive and negative groups were compared using a two-tailed t test with 95% CI, p < 0.05. The results were compared between cities. The statistical software SAS 9.0 was used. The total number of patients included in the study was 717 infants that met the inclusion criteria. The average age of the patients was 3.6 months (SD 3.25), with a male/female ratio of 4:3. The primary diagnoses of the patients included: bronchiolitis in 67.0%, pneumonia in 23.0%, bronchopneumonia in 9.8%, and other in 0.3%. The RSV test was positive in 216 patients, which corresponds to an incidence of 30.0% in the general study population (Table 1). In the other cities the range of variability of RSV positivity was 23.8% to 49.0% (Table 1).