Secondhand smoke exposure and asthma outcomes among African-American and Latino children with asthma

Neophytou, A. M.; Oh, S. S.; White, M. J.; Mak, A. C. Y.; Hu, D.; Huntsman, S.; Eng, C.; Serebrisky, D.; Borrell, L. N.; Farber, H. J.; Meade, K.; Davis, A.; Avila, P. C.; Thyne, S. M.; Rodriguez-Cintron, W.; Rodriguez-Santana, J. R.; Kumar, R.; Brigino-Buenaventura, E.; Sen, S.; Lenoir, M. A.; Williams, L. K.; Benowitz, N. L.; Balmes, J. R.; Eisen, E. A.; Burchard, E. G.

Thorax. 2018 Jun 15

Abstract

BACKGROUND: Secondhand smoke (SHS) exposures have been linked to asthma-related outcomes but quantitative dose-responses using biomarkers of exposure have not been widely reported. OBJECTIVES: Assess dose-response relationships between plasma cotinine-determined SHS exposure and asthma outcomes in minority children, a vulnerable population exposed to higher levels of SHS and under-represented in the literature. METHODS: We performed analyses in 1172 Latino and African-American children with asthma from the mainland USA and Puerto Rico. We used logistic regression to assess relationships of cotinine levels >/=0.05 ng/mL with asthma exacerbations (defined as asthma-related hospitalisations, emergency room visits or oral steroid prescription) in the previous year and asthma control. The shape of dose-response relationships was assessed using a continuous exposure variable in generalised additive logistic models with penalised splines. RESULTS: The OR for experiencing asthma exacerbations in the previous year for cotinine levels >/=0.05 ng/mL, compared with <0.05 ng/mL, was 1.40 (95% CI 1.03 to 1.89), while the OR for poor asthma control was 1.53 (95% CI 1.12 to 2.13). Analyses for dose-response relationships indicated increasing odds of asthma outcomes related with increasing exposure, even at cotinine levels associated with light SHS exposures. CONCLUSIONS: Exposure to SHS was associated with higher odds of asthma exacerbations and having poorly controlled asthma with an increasing dose-response even at low levels of exposure. Our results support the conclusion that there are no safe levels of SHS exposures.

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