Pathways through which asthma risk factors contribute to asthma severity in inner-city children.
BACKGROUND
Pathway analyses can be used to determine how host and environmental factors contribute to asthma severity.


OBJECTIVE
To investigate pathways explaining asthma severity in inner-city children.


METHODS
On the basis of medical evidence in the published literature, we developed a conceptual model to describe how 8 risk-factor domains (allergen sensitization, allergic inflammation, pulmonary physiology, stress, obesity, vitamin D, environmental tobacco smoke [ETS] exposure, and rhinitis severity) are linked to asthma severity. To estimate the relative magnitude and significance of hypothesized relationships among these domains and asthma severity, we applied a causal network analysis to test our model in an Inner-City Asthma Consortium study. Participants comprised 6- to 17-year-old children (n = 561) with asthma and rhinitis from 9 US inner cities who were evaluated every 2 months for 1 year. Asthma severity was measured by a longitudinal composite assessment of day and night symptoms, exacerbations, and controller usage.


RESULTS
Our conceptual model explained 53.4% of the variance in asthma severity. An allergy pathway (linking allergen sensitization, allergic inflammation, pulmonary physiology, and rhinitis severity domains to asthma severity) and the ETS exposure pathway (linking ETS exposure and pulmonary physiology domains to asthma severity) exerted significant effects on asthma severity. Among the domains, pulmonary physiology and rhinitis severity had the largest significant standardized total effects on asthma severity (-0.51 and 0.48, respectively), followed by ETS exposure (0.30) and allergic inflammation (0.22). Although vitamin D had modest but significant indirect effects on asthma severity, its total effect was insignificant (0.01).


CONCLUSIONS
The standardized effect sizes generated by a causal network analysis quantify the relative contributions of different domains and can be used to prioritize interventions to address asthma severity.
['Liu|Andrew H|AH|', 'Babineau|Denise C|DC|', 'Krouse|Rebecca Z|RZ|', 'Zoratti|Edward M|EM|', 'Pongracic|Jacqueline A|JA|', "O'Connor|George T|GT|", 'Wood|Robert A|RA|', 'Khurana Hershey|Gurjit K|GK|', 'Kercsmar|Carolyn M|CM|', 'Gruchalla|Rebecca S|RS|', 'Kattan|Meyer|M|', 'Teach|Stephen J|SJ|', 'Makhija|Melanie|M|', 'Pillai|Dinesh|D|', 'Lamm|Carin I|CI|', 'Gern|James E|JE|', 'Sigelman|Steven M|SM|', 'Gergen|Peter J|PJ|', 'Togias|Alkis|A|', 'Visness|Cynthia M|CM|', 'Busse|William W|WW|']
D000293:Adolescent D001249:Asthma D002648:Child D019468:Disease Management D004781:Environmental Exposure D005260:Female D006801:Humans D008297:Male D008962:Models, Theoretical D011203:Poverty D012221:Rhinitis, Allergic, Perennial D012307:Risk Factors D012720:Severity of Illness Index D014028:Tobacco Smoke Pollution D014505:Urban Population
Asthma inner-city children sensitization inflammation pulmonary physiology rhinitis allergy environmental tobacco smoke exposure lung function