Association of mold levels in urban children's homes with difficult-to-control asthma.

Background: Mold sensitization and exposure are associated with asthma severity, but the specific species that contribute to difficult-to-control (DTC) asthma are unknown.

Objective: We sought to determine the association between overall and specific mold levels in the homes of urban children and DTC asthma.

Methods: The Asthma Phenotypes in the Inner-City study recruited participants, aged 6 to 17 years, from 8 US cities and classified each participant as having either DTC asthma or easy-to-control (ETC) asthma on the basis of treatment step level. Dust samples had been collected in each participant's home (n = 485), and any dust remaining (n = 265 samples), after other analyses, was frozen at -20C. The dust samples (n = 265) were analyzed using quantitative PCR to determine the concentrations of the 36 molds in the Environmental Relative Moldiness Index. Logistic regression was performed to discriminate specific mold content of dust from homes of children with DTC versus ETC asthma.

Results: Frozen-dust samples were available from 54% of homes of children with DTC (139 of 253) and ETC asthma (126 of 232). Only the average concentration of the mold Mucor was significantly (P < .001) greater in homes of children with DTC asthma. In homes with window air-conditioning units, the Mucor concentration contributed about a 22% increase (1.6 odds ratio; 95% CI, 1.2-2.2) in the ability to discriminate between cases of DTC and ETC asthma.

Conclusions: Mucor levels in the homes of urban youth were a predictor of DTC asthma, and these higher Mucor levels were more likely in homes with a window air-conditioner.