title: Risk factors for recurrent wheezing following acute bronchiolitis: a 12-month follow-up.
abstract: The objective of this study was to identify wheezing recurrences and related risk factors in two groups of infants with bronchiolitis: respiratory syncytial virus (RSV)+ and RSV- as determined by RSV enzyme immunoassay. A 1-year prospective cohort study was conducted with infants younger than 2 years old. Follow-up was made monthly, by a clinical visit and/or by telephone, checking the number of wheezing episodes per month and possible related risk factors. There were 96 subjects enrolled, of whom 77 reached complete follow-up: 36 were RSV+ (46.8%), and 41 were RSV- (53.2%). In the RSV+ group, there were 17 males (47%), vs. RSV- with 30 males (73%) (P < 0.05); 22 RSV+ (61%) were admitted to hospital, vs.14 RSV- (34%) (P < 0.05). Mean age was not significantly different in both groups. The mean number of recurrences was 3.36 episodes/infant/year in the RSV+ and 2.34 in the RSV- group (P = 0.06). Crude relative risk (RR) for a new recurrence of an obstructive episode was 1.33 (95% CI, 0.99-1.79). After adjustment for several potential confounders, the RR was 1.41 (95% CI, 1.03-1.93). Hospitalization stay was longer in the RSV+ than the RSV- group (P < 0.05). In the RSV+ group, patients who had been hospitalized showed more recurrences (4.18) than those with outpatient treatment (2.07) (P < 0.05); this difference did not exist in the RSV- group. The related risk factors for recurrent wheeze in the RSV- group were male gender, number of siblings, and daycare attendance (P < 0.05). In the RSV+ group, the risk of recurrent wheeze was only increased by admission to hospital during the acute bronchiolitis episode (P < 0.05). We speculate that there may be a higher rate of increased airway reactivity and/or preexisting diminished lung function in RSV+ infants requiring hospitalization for their initial illness. In conclusion, RSV-proven bronchiolitis, particularly in those infants who are hospitalized, is associated with a higher recurrence of wheezing episodes in the subsequent 12 months. Other factors appear to account for recurrent wheeze in the RSV- group.
authors.affiliation: Ambulatory Service, Department of Pediatrics, School of Medicine, Catholic University of Chile, Lira 85, Santiago de Chile, 833-0074 Chile. lcifuen@med.puc.cl
authors.forename: Lorena
authors.initials: L
authors.lastname: Cifuentes
authors.forename: Solange
authors.initials: S
authors.lastname: Caussade
authors.forename: Claudia
authors.initials: C
authors.lastname: Villagrán
authors.forename: Paula
authors.initials: P
authors.lastname: Darrigrande
authors.forename: Paula
authors.initials: P
authors.lastname: Bedregal
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Valdivia
authors.forename: Ignacio
authors.initials: I
authors.lastname: Sánchez
mesh_terms: D000208:Acute Disease; D001988:Bronchiolitis / Q000150:complications* / Q000821:virology; D002656:Child Day Care Centers; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D011446:Prospective Studies; D012008:Recurrence; D012135:Respiratory Sounds / Q000209:etiology*; D018357:Respiratory Syncytial Virus Infections / Q000150:complications*; D012307:Risk Factors; D012737:Sex Factors; D035781:Siblings