The Population Attributable Fraction of Asthma Among Canadian Children

Abstract

sthma is a leading cause of chronic illness among Canadian children. Quantifying the relative contributions of modifiable exposures to the development of Canadian childhood asthma may identify the most effective targets for individual and societal intervention and suggest future research targets. Our objective was to determine the population attributable fraction (PAF) of childhood asthma in Canada due to modifiable environmental exposures, including particulates, nitrogen dioxide (NO 2), environmental tobacco smoke (ETS), cat, dog, mouse, cockroach, dust mites, moisture and mould, in order to estimate their relative contributions to childhood asthma development. The PAF, or proportion of childhood asthma in Canada that may be attributed to these exposures, was calculated using Canadian childhood asthma incidence, Canadian pollutant exposure prevalence, and international estimates of the risk of asthma development associated with exposure. METHODS Inclusion and exclusion criteria Canadian Childhood Asthma Incidence Estimates of asthma incidence among Canadian children were obtained from representative national surveys-the National Longitudinal Survey of Children and Youth (NLSCY) 1 and the National Population Health Survey (NPHS) 2-and population or administrative databases. 3,4 Canadian Exposure Prevalence Canadian environmental pollutant and allergen exposure prevalences were estimated from websites of government agencies and published studies. Cut points for airborne pollutant levels contributing to asthma development have not been defined; therefore, we used the 2005 World Health Organization Air Quality Standards, 5 which have been associated with cardio-respiratory problems [PM 10 50 μg/m 3 , PM 2.5 25 μg/m 3 , NO 2 21 parts per billion (ppb), O 3 47 ppb, and SO 2 7.1 ppb]. The Canada-Wide Air Quality Standard 6 was used for CO (11 parts per million) in the absence of a WHO Standard. The prevalence of environmental tobacco smoke (ETS) exposure was obtained from the Canadian Tobacco Use Monitoring Survey. 7 Pet, pest, moisture and mould exposures were selfreported, observed, or determined using allergen levels associated with asthma symptom development (cat >8μg/g, dog >10μg/g, mouse >1.6μg/g, cockroach >8U/g and dust mites >10μg/g).

Burden of disease attributable to second-hand smoke exposure: A systematic review

“…60 Data sources: In almost all the studies, the burden was estimated for countries or regions using official statistics. Two studies applied the CRA methodology to data (prevalence, costs) from survey samples , [43][44] Shin et al 45 estimated and applied the PAF in a cohort, Simons et al 79 Outcomes: The SHS-attributable burden of disease was mainly studied in terms of mortality (55.6% of the studies), followed by morbidity (33.3%), DALYs (22.2%) and costs (18.1%). Some studies investigated also the burden from hospital admissions or years of potential life lost (Table 1).…”

Household biomass fuel use, asthma symptoms severity, and asthma underdiagnosis in rural schoolchildren in Nigeria: a cross-sectional observational study

“…Reasons for this trend are currently unclear, but factors including lifestyle changes [1–3], environmental challenges (such as traffic-related pollution) [4], and tobacco smoke exposure [2, 5], dust mites [6], indoor dampness and molds [7], and pets [4] have been implicated. Additionally, household air pollution (HAP) from the use of biomass for cooking is increasingly being recognized as a risk factor for asthma and other respiratory symptoms, especially in low- and middle-income countries (LMIC) [8, 9].…”

Indoor mold levels and current asthma among school-aged children in Saskatchewan, Canada

“…Asthma is a common chronic condition in children and remains the leading cause of childhood morbidity as measured by hospitalization and school absences (Garner and Kohen, ; Moonie et al., ; Simons et al., ). Currently, approximately 10% of Canadian children (aged 2–7 years) are diagnosed with asthma (Statistics Canada ).…”

“…Currently, approximately 10% of Canadian children (aged 2–7 years) are diagnosed with asthma (Statistics Canada ). While asthma prevalence continues to increase among children (Simons et al., ), the etiology of the disease is not firmly established. Generally, studies have found that lifestyle changes (Konstantaki et al., ; Rodriguez et al., ) and exposure to certain environmental agents (Han et al., ; Simons et al., ) are likely explanations for the apparent increase in prevalence.…”