Influence of neighbourhood characteristics on asthma outcomes in an asthma clinic cohort of youths
Résumé
Background
Asthma is the most common chronic illness among children. We aimed to better understand the association of neighbourhood context with asthma control and the moderating effect of obesity status on this association.
Methods
Data were from an asthma clinic cohort (n = 4621) of Montreal youths aged 2-18 years, recruited in 2000-2007 and followed for up to 6 years. Clinical data were linked with medical records on acute care visits and hospitalizations. Neighbourhoods were defined by the 750 m buffer around youths’ postal codes. Using spatial data, neighbourhood context was described by high or low deprivation (D) and walkability (W). Asthma control was based on a composite indicator of all adverse events. The outcome was described by the event rate, i.e. total number of composite events by duration of exposure (time in neighourhood). A Poisson model was fitted to predict asthma control rates by neighbourhood context, controlling for individual covariates and an air pollution index based on spatial exposure estimates. We used the Baron-Kenny framework to test for effect modification by obesity status.
Results
Asthma control was independently predicted by neighbourhood context. Youth living in low D, high W areas had better asthma control compared with those living in high D low W (IRR=0.83, 95%CI 0.69,0.99, p = 0.04) and those in high D high W (IRR=0.80, 95%CI 0.67,0.95, p = 0.01) areas. Within low D areas, higher W was associated with greater asthma control (IRR=0.88, 95%CI 0.76,1.01, p = 0.07). No other associations were found and obesity did not modify the association between neighbourhood context and asthma control.
Conclusions
Higher deprivation is associated with lower rates of asthma control among youth; moreover, high walkability may have a protective effect in low deprivation areas. Efforts to reduce area deprivation may benefit youth suffering from poor asthma control; increasing walkability may be especially beneficial in the absence of area deprivation.