A spatial analysis of asthma prevalence in Ontario

The objective of this paper is to examine spatial patterns of asthma prevalence in the province of Ontario by age and sex between 2002 and 2006.

We conducted a population-based, ecological-level study using the Ontario Asthma Surveillance Information System Database (OASIS), a validated registry of all Ontario residents with asthma. Data were mapped and analyzed at the sub-Local Health Integration Network (subLHIN) level (n=141). Comparative morbidity figures (CMFs) were calculated and analyzed for local clusters of high and low values ("hot spots" and "cold spots").

There were 1,601,353 individuals identified as having asthma over the study period, representing an overall prevalence rate of 12.93%. Results demonstrate distinct spatial patterns of asthma prevalence across the province which are age- and sex-specific. There was little overlap between asthma hot spots by age group, suggesting that different spatial processes are at play. Patterns of cold spots are consistently seen in the urban and suburban subLHINs in and around Toronto and Hamilton as well as in several of the highly rural northern subLHINs.

Findings illustrate the need for more geographically focused public health and health care planning and resource allocation, and highlight the need for research aimed at understanding the factors that may explain the spatial patterns identified here.