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A new study highlights the benefits of using hair samples over other methods for assessing tobbacco smoke exposure (TSE), including caregiver reports, which may not always be accurate.

Tobacco smoke and preemies with lung disease

Public health experts know that tobacco smoke exposure (TSE) can be harmful to children with bronchopulmonary dysplasia (BPD), a lung disease that often accompanies premature birth. Findings now suggest high levels of second-hand and caregiver smoking greatly contribute to further decline in the health of these infants.

A small study, led by Johns Hopkins Children's Center investigators. having measured nicotine levels in infant hair samples, affirms that TSE is common in infants with BPD, whose caregivers claim not to smoke at home. The findings are published online Feb. 2 in the journal Pediatrics.
"We found that more than one-fifth of children whose caregivers report nonsmoking households have significant exposure. The hope is that our study will lead to better ways to protect this vulnerable population of children," says investigator Sharon McGrath-Morrow, M.D., M.B.A., professor of pediatrics and a lung specialist at Johns Hopkins Children's Center.

McGrath-Morrow says about one-half of children born at less than 1,000 grams, or about 2.2 pounds, develop BPD. Because these premature infants are particularly sensitive to TSE, which continues to damage frail lungs, doctors routinely ask caregivers about smoking habits and then verify exposure by testing an infant's urine, saliva, or blood. However, taking blood samples is traumatic to infants and young patients, and blood, urine and saliva only show TSE within hours or days, rather than long-term.

Seeking a better marker for TSE detection, McGrath-Morrow along with coauthor Joseph Collaco, MD, MBA, MPH, pediatric lung specialist at Johns Hopkins Children's Center, and their colleagues tested small locks of hair. Hair collects evidence of TSE over weeks or months and offers a more accurate picture of a child's smoking environment.

After combining results of hair analysis with parent and caregiver questionnaires, researchers found about 20 percent of the patients had TSE. Nicotine levels in hair samples increased along with the number of household smokers that caregivers self-reported on questionnaires. However, 22 percent of children whose caregivers reported living in nonsmoking households — showed significant TSE similar to children who reported living in smoking households. This result suggests either parents weren't correctly reporting smoking habits or children were exposed elsewhere.

Some of the children may have been exposed in multiunit housing, where about half of the families lived. However, as the finding was not statistically significant, it may have been due to chance. But, higher nicotine levels were seen in patients of nonsmoking families living in multiunit buildings — buildings that allow smoking.

Researchers saw a six to seven-fold increase in the most vulnerable children at risk for hospitalization and activity limitations as nicotine levels in their hair increased. McGrath-Morrow believes although doctors typically educate caregivers on the dangers of TSE in children with BPD, the new findings show more must be done.

"If we could prevent TSE in these children, they'd likely have better outcomes."

Sharon McGrath-Morrow, M.D., M.B.A., professor of pediatrics and a lung specialist at Johns Hopkins Children's Center.

"Although not available for clinical use now, we hope hair sampling may be readily available in the future to assess tobacco smoke exposure in children."

Joseph Collaco, MD, MBA, MPH, pediatric lung specialist at Johns Hopkins Children's Center

Abstract
OBJECTIVES: Infants and children with chronic lung disease of prematurity (CLDP) are at increased risk for morbidity and mortality from respiratory viral infections. Exposure to respiratory viruses may be increased in the day care environment. The risk of respiratory morbidity from day care attendance in the CLDP population is unknown. We therefore sought to determine if day care attendance is a significant risk factor for increased respiratory morbidity and symptoms in infants and children with CLDP.

METHODS: Between January 2008 and October 2009, parents of infants and children with CLDP were surveyed. Information on perinatal history, sociodemographic information, day care attendance, and indicators of respiratory morbidity, including emergency department (ED) visits, hospitalizations, systemic corticosteroid use, antibiotic use, and respiratory symptoms, was collected on children <3 years of age. Logistic regression models were constructed to examine associations between exposure to day care and respiratory morbidities.

RESULTS: Data were collected from 111 patients with CLDP. The average gestational age was 26.2 ± 2.0 weeks. Day care attendance was associated with significantly higher adjusted odds for ED visits (odds ratio [OR]: 3.74 [95% confidence interval (CI): 1.41–9.91]; P < .008), systemic corticosteroid use (OR: 2.22 [CI: 1.10–4.49]; P < .026), antibiotic use (OR: 2.40 [CI: 1.08–5.30]; P < .031), and days with trouble breathing (OR: 2.72 [CI: 1.30–5.69]; P < .008). Although there was an increased OR for hospitalization (OR: 3.22 [CI: 0.97–10.72]; P < .057), this did not reach statistical significance.

CONCLUSIONS: We found that day care attendance is associated with increased respiratory morbidities in young children with CLDP. Physicians should consider screening for and educating caregivers about the risks of day care attendance by young children with CLDP.

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Other researchers who contributed to this study include Angela D. Aherrera of Johns Hopkins and Patrick N. Breysse, Jonathan P. Winickoff, and Jonathan D. Klein of the American Academy of Pediatrics.

The work was funded by a Center of Excellence grant to the American Academy of Pediatrics from the Flight Attendant Medical Research Institute and a Johns Hopkins Center of Excellence grant from the Flight Attendant Medical Research Institute.

Johns Hopkins Medicine (JHM), headquartered in Baltimore, Maryland, is a $7 billion integrated global health enterprise and one of the leading academic health care systems in the United States. JHM unites physicians and scientists of the Johns Hopkins University School of Medicine with the organizations, health professionals and facilities of The Johns Hopkins Hospital and Health System. JHM's vision, "Together, we will deliver the promise of medicine," is supported by its mission to improve the health of the community and the world by setting the standard of excellence in medical education, research and clinical care. Diverse and inclusive, JHM educates medical students, scientists, health care professionals and the public; conducts biomedical research; and provides patient-centered medicine to prevent, diagnose and treat human illness. JHM operates six academic and community hospitals, four suburban health care and surgery centers, and 39 primary and specialty care outpatients sites under the umbrella of Johns Hopkins Community Physicians. The Johns Hopkins Hospital, opened in 1889, has been ranked number one in the nation by U.S. News & World Report for 22 years of the survey's 25 year history, most recently in 2013. For more information about Johns Hopkins Medicine, its research, education and clinical programs, and for the latest health, science and research news, visit http://www.hopkinsmedicine.org.

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