Definitions of adult asthma using health administrative data are sensitive and specific for identifying adults with asthma. Using these definitions, cohorts of adults with asthma for ongoing population-based surveillance and research can be developed.

Our findings indicate a substantial increase in COPD prevalence in the last decade, with more of the burden being shifted from men to women. Effective clinical and public health strategies are needed to prevent COPD and manage the increasing number of people living longer with this disease.

In the 1980s and early 1990s, asthma prevalence increased significantly in most Westernized countries. In more recent years, asthma trends have been less clear, with some studies suggesting that they are still rising and others suggesting that they have stabilized or decreased. A population-based cohort study was conducted to estimate asthma prevalence and incidence trends in one large Canadian province, Ontario. All individuals with asthma living in Ontario, a province of Canada with a multicultural population of approximately 12 million, were identified in universal, population health administrative databases by using a validated health administrative case definition of asthma. Annual asthma prevalence, incidence, and all-cause mortality rates were estimated from 1996 to 2005. During this time, the prevalence of asthma increased by 70.5%. The age- and sex-standardized asthma prevalence increased from 8.5% in 1996 to 13.3% in 2005, a relative increase of 55.1% (P < 0.0001). Asthma incidence rates increased in children by 30.0% and were relatively stable in adults. Overall all-cause mortality decreased. Asthma prevalence in Ontario, Canada, has increased significantly. This is attributable, in part, to an increase in the incidence of asthma in children. Effective clinical and public health strategies are needed to prevent and manage asthma in the population.

Background and aims Asthma comorbidity, such as depression and obesity, has been associated with greater healthcare use, decreased quality of life and poor asthma control. Treating this comorbidity has been shown to improve asthma outcomes as well as overall health. Despite this, asthma comorbidity remains relatively under-recognised and understudieddperhaps because most asthma occurs in young people who are believed to be healthy and relatively free of comorbidity. The aim of this study was to quantify empirically the amount of comorbidity associated with asthma. Methods A population-based cohort study was conducted using the health administrative data of the 12 million residents of Ontario, Canada in 2005. A validated health administrative algorithm was used to identify individuals with asthma. Results The amount of comorbidity among individuals with asthma, as reflected in rates of hospitalisations, emergency department visits and ambulatory care claims, was found to be substantial and much greater than that observed among individuals without asthma. Together, asthma and asthma comorbidity (the extra comorbidity found in individuals with asthma compared with those without asthma) were associated with 6% of all hospitalisations, 9% of all emergency room visits and 6% of all ambulatory care visits that occurred in Ontario. Conclusions Asthma comorbidity places a significant burden on individuals and the healthcare system and should be considered in the management of asthma. Further research should focus on which types of asthma comorbidity are responsible for the greatest burden and how such comorbidity should be prevented and managed.

BackgroundAsthma comorbidity has been correlated with poor asthma control, increased health services use, and decreased quality of life. Managing it improves these outcomes. Little is known about the amount of different types of comorbidity associated with asthma and how they vary by age.Methodology/Principal FindingsThe authors conducted a population study using health administrative data on all individuals living in Ontario, Canada (population 12 million). Types of asthma comorbidity were quantified by comparing physician health care claims between individuals with and without asthma in each of 14 major disease categories; results were adjusted for demographic factors and other comorbidity and stratified by age. Compared to those without asthma, individuals with asthma had higher rates of comorbidity in most major disease categories. Most notably, they had about fifty percent or more physician health care claims for respiratory disease (other than asthma) in all age groups; psychiatric disorders in individuals age four and under and age 18 to 44; perinatal disorders in individuals 17 years and under, and metabolic and immunity, and hematologic disorders in children four years and under.Conclusion/SignificanceAsthma appears to be associated with significant rates of various types of comorbidity that vary according to age. These results can be used to develop strategies to recognize and address asthma comorbidity to improve the overall health of individuals with asthma.