Asthma: Secondhand Smoke Doubles Kids' Hospitalization Risk

Diana Phillips

September 24, 2015

Exposure to secondhand smoke nearly doubles the risk for hospitalization for an asthma exacerbation in children with asthma, according to the findings of a systematic review and meta-analysis.

This twofold difference in hospitalization risk is clinically important because hospitalizations for asthma have been linked with increased mortality and poorer disease control, the authors note in an article published online September 24 in the Annals of Allergy, Asthma and Immunology.

"This is the first time the risk has been quantified," write Zhen Wang, PhD, from the Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, Minnesota, and colleagues. The information will help healthcare providers convey to parents of asthmatic children the magnitude of the dangers associated with secondhand smoke, they explain. "It also illustrates the increased burden of disease on the health care system with increased rates of hospitalizations," they write.

Of 1945 studies identified, 25 observational studies evaluated children younger than 18 years and reported outcomes related to asthma severity, and as such were included in the review. The majority of studies (96%) investigated smoking exposure in the home. The asthma-related outcomes included hospitalization; emergency department or urgent care visits; medication use, including oral steroids; clinical symptoms; acute exacerbations; and pulmonary function measurements.

Overall, data from 434,737 children (mean age, 7.6 years) were included in the review. Random effect models combining the outcomes of interest showed that the odds ratio for hospitalization among children with secondhand smoke exposure relative to those with no exposure was 1.85 (95% confidence interval [CI], 1.20 - 2.86; P = .01).

Secondhand smoke exposure also was significantly associated with emergency department or urgent care visits and wheezing, with respective odds ratios of 1.66 (95% CI, 1.02 - 2.69; P = .04) and 1.32 (95% CI, 1.24 - 1.41; P < .001), the authors report.

The authors found no statistically significant difference in frequency of asthma exacerbation or in forced expiratory volume in 1 second; however, the ratio of forced expiratory volume in 1 second to forced vital capacity was significantly lower in children with secondhand smoke exposure.

The findings indicate that subjective and objective assessment of secondhand smoke exposure "should be an integral part of asthma care in children," the authors state. "This will help address and eliminate modifiable risk factors and improve the overall health of children with asthma."

This study was funded by the Mayo Clinic Center for Innovation. The authors have disclosed no relevant financial relationships.

Ann Allergy Asthma Immunol. Published online September 24, 2015. Abstract


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