SHORT-TERM IMPACT OF BRONCHIOLITIS SEVERITY ON THE DURATION OF SYMPTOMS AND RECURRENCE OF WHEEZING. Natalia Paniagua*, MD; Olaia Lopez*, MD; Ainhoa Ibarrola*, MD; June Udaondo*, MD; Raquel Rubio*, MD; Lorea Martinez-Indart**; Javier Benito*, PhDMD. *Pediatric Emergency Department- Cruces University Hospital. **Clinic Epidemiology Unit- Cruces University Hospital. BACKGROUND Studies have shown the effect of Bronchiolitis on the well-being of children. However, it remains to be shown whether there is a relationship between disease severity and the duration of symptoms. OBJECTIVES 1- To evaluate whether the severity of the episode of bronchiolitis is related with a longer duration of symptoms. 2- To investigate recurrence of wheezing in correlation with severity of bronchiolitis. PATIENTS AND METHODS This is a prospective cohort study evaluating children presenting in a pediatric emergency department (PED) diagnosed with bronchiolitis between November-2013 and February-2014. Two follow-up telephone interviews were completed at 4 and 12 weeks after the PED visit. In the first telephone interview, parents were asked about the persistence of symptoms of bronchiolitis (cough, runny nose, aspiration of secretions, wheeze, short of breath). In the second one, they were asked about recurrence of wheezing. The primary outcome measures were the number of days of persistent symptoms, comparing children discharged at home with those admitted. A difference of three days was considered clinically significant. RESULTS The first follow-up telephone interview was completed in 214 cases, 115 children discharged (53.7%), 99 admitted (46.3%). The mean age and severity score in infants admitted and those discharged was 3.9 ± 4.3 vs 7.1 ± 3.9, p<0.01 and 2.63 ± 1.46 vs 1.10 ± 1.06, p<0.01 respectively. One hundred and fifty eight patients (74.17%) showed a positive result of the respiratory syncytial virus (RSV) rapid test in nasopharyngeal specimens without differences between the study groups. There were no differences between children admitted than those discharged in duration of cough and runny nose (11.8 ± 7.3 vs 11.5 ± 5.9, ns; 14.1 ± 8.3 vs 12.7 ± 5.7, ns, respectively). However, parents of patients discharged at home remarked a superior duration of wheezing and short of breath (8.8 ± 5 vs 5.2 ± 4.9, p<0.01; 12 ± 6.2 vs 7.8 ± 6.6, p<0.01, respectively). Admitted children needed nasal suctioning a greater number of days (15.5 ± 8.9 vs 13 ± 6.1, p<0.05). Global wheezing recurrence was 31.4%, with no differences between the two groups (32% ± 4.7 vs 30% ± 4.6) and similar duration of recurrence episodes (6.7 ± 4.3 days vs 7.3 ± 5.4 days). CONCLUSION Bronchiolitis severity seems to be neither related with a longer duration of symptoms four weeks after PED presentation nor a higher rate of recurrence of wheezing twelve weeks later. Short term follow-up must be recommended regardless initial severity.