OBJECTIVES: To investigate individual factors associated with an @entity565 outbreak among @entity1 aged one to 14 years in Sydney in February 1999. METHODS: A case control study was undertaken with cases (n=92) defined as all @entity1 admitted to Sydney @entity1 's Hospital for @entity565 in February 1999. Unmatched controls (n=76) were all @entity1 admitted for @entity565 in the previous three months. We obtained information by a structured telephone survey of parents. Logistic regression analyses were used to determine odds ratios for risk factors for hospital admission. RESULTS: Mean age for hospital admission of 4.7 years for cases and 4.4 years for controls. The presence of one or more siblings reduced the risk of admission during an @entity565 outbreak (OR=0.59, 95% CI 0.37 to 0.93). @entity1 with older siblings aged 10 to 14 years were also less likely to be admitted (OR=0.3, 95% CI 0.12 to 0.74). An age effect was observed. Other demographic, clinical and environmental characteristics, including smoking, were not associated with admission during the outbreak. CONCLUSIONS: The main findings of this study are the protective effect of siblings and an age-dependent effect in risk of hospital admission during an @entity565 outbreak. These findings are consistent with an infective cause of the outbreak. IMPLICATIONS: @entity1 without siblings, particularly older siblings, appear to be at highest risk of hospital admission during an @entity565 outbreak. Environmental and other factors need to be examined to further explain the episodicity of such outbreaks and to determine means of predicting and preventing future episodes.

XXXX outbreaks in NSW: a case control study.

@entity1 :: ('9606', 'Species') :: ['children', 'Children'] @entity565 :: ('MESH:D001249', 'Disease') :: ['asthma']
@entity565 :: (MESH:D001249,Disease) :: ['February asthma']
