Phone Calls to Emergency Practitioners for Asthma Attacks and Contextual Socioeconomic Status

Abstract

Objective: Phone calls to mobile emergency practitioner networks are increasingly used as health surveillance indicators. As part of the PAISA (Air Pollution and Socioeconomic Inequalities in Asthma) project, we tested whether rates of emergency phone calls for asthma attacks are associated with contextual socioeconomic status in an eastern France conurbation of 450,000 inhabitants. Material and Methods: Data on 4683 emergency calls for asthma attacks (georeferenced by IRIS, ∼2000 inhabitants, comparable to US Census Block Group) were obtained from the 2 emergency practitioner networks operating in the conurbation for years 2000 to 2005. Contextual socioeconomic status was measured by a composite index, constructed by principal component analysis from 19 socioeconomic variables at the IRIS resolution. Rates of emergency calls were calculated for each IRIS and for different age groups. Instability of extreme rates due to low numbers of incident cases in some IRIS was lessened by smoothing with an empirical Bayesian approach. Results: Positive spatial autocorrelation between adjacent IRIS was detected in health and socioeconomic datasets. In all age groups, rates of calls for asthma attacks increased linearly as contextual socioeconomic level decreased. Pearson correlation coefficients between these 2 factors varied depending on the age group: 0.53 for 0- to 9-years-old, 0.46 for 10- to 19-years-old, 0.65 for 20- to 39-years-old, 0.70 for 40- to 64-years-old, 0.68 for 65-years-old and older, and 0.77 for age-standardized incidence ratio. These correlation coefficients were strongly statistically significant (P < 0.01), even when spatial autocorrelation was adjusted for by Clifford's modified t test. Conclusions: Emergency phone calls for asthma attacks were positively associated with contextual socioeconomic deprivation. This is consistent with socioeconomic gradients reported in