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Shastri SS, Talluri R, Shete S. Disparities in Secondhand Smoke Exposure in the United States: National Health and Nutrition Examination Survey 2011-2018. JAMA Intern Med. 2021;181(1):134–137. doi:10.1001/jamainternmed.2020.3975
Secondhand smoke exposure (SHSe) is one of the causes of sudden infant death syndrome, respiratory tract infections, ear infections, and asthma attacks in infants and children; coronary heart disease, stroke, and lung cancer in adult nonsmokers; and low birth weight, premature deliveries, and congenital defects in pregnancies.1 It results in nearly 42 000 deaths (more than 41 000 adults and 900 infants) among nonsmokers every year in the US, with Black individuals accounting for 24% to 36% of the infant deaths.2 The US Surgeon General determined that there is no risk-free level of SHSe.3 With the outbreak of coronavirus disease 2019, which affects lung function, improving smoke-free policies to enhance air quality should be a growing priority.
This study was conducted using data from 4 cycles of the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018. The most recent data (2017-2018) were released in March 2020. The NHANES is designed to monitor nationwide health and uses a complex, multistage probability design to sample the noninstitutionalized civilian population residing in all 50 states.4 Sensitive and personal questions are administered through computer-assisted personal interview and the audio computer-assisted self-interview. The biological specimens for laboratory testing were collected at a mobile examination center. Among nonsmokers, individuals having serum cotinine levels of 0.05 to 10 ng/mL were considered to have SHSe. The primary outcome of this study is the prevalence of SHSe in nonsmokers in the US population 3 years and older. Because the NHANES data are deidentified and publicly available, this secondary data analysis was exempt from institutional review board approval and informed consent in accordance with the Common Rule and University of Texas MD Anderson Cancer Center policy.
The survey-adjusted weights were used to estimate the prevalence of SHSe in nonsmokers. A survey logistic regression was used to test for trends in SHSe over the 4 two-year intervals (2011-2012, 2013-2014, 2015-2016, and 2017-2018) of NHANES. Also, a multivariable survey logistic regression was performed to identify factors associated with SHSe. For all statistical analyses, P values were calculated using Wald test statistic, and significance was defined as 2-sided P value ≤ .05. The analysis was performed using the survey package in R, version 4.0.0 (R Foundation for Statistical Computing).
This study found that disparities in SHSe among non-Hispanic Black individuals compared with people of other races and among those below the poverty levels have persisted throughout 2011 to 2018 (Table 1). For example, in the 2017-2018 cycle, the SHSe prevalence continued to be twice as high among nonsmoker non-Hispanic Black individuals (48.02%) compared with non-Hispanic White individuals (22.03%) and among those living below the poverty level (44.68%) compared with those living above the poverty level (21.33%). Similarly, children aged 3 to 11 years continued to experience SHSe at high rates (38.23%). Multivariable logistic regression identified younger age (odds ratio [OR], 1.88, for 12-19 years, and OR, 2.29, for 3-11 years), non-Hispanic Black race/ethnicity (OR, 2.75), less than high school education (OR, 1.59), and living below the poverty level (OR, 2.61) as risk factors for SHSe in the 2017 to 2018 cycle, with little change across all data cycles (Table 2).
Although the prevalence of SHSe among nonsmokers in the US declined substantially (87.5% to 25.3%) from 1988 to 2012,5 progress has stagnated since then, with persisting racial and economic disparities. Populations with a lower socioeconomic status have higher smoking rates, lower knowledge about health risks of tobacco, higher risk of workplace exposure, and higher likelihood of living in low-income multi-unit housing and have their communities targeted more by tobacco companies, which would possibly explain the high SHSe observed in our study. Furthermore, in households with smokers, non-Hispanic Black individuals are less likely to have a complete smoking ban in homes, while parents of any race or ethnicity with a child on Medicaid or uninsured (a proxy for lower income) are less likely to have a complete smoking ban in family vehicles. We conclude that more needs to be done to implement enhanced and equitable comprehensive smoke-free laws throughout the US (currently implemented in only 27 states). The serum cotinine levels in nonsmokers provide a measure of overall SHSe, regardless of the sources or locations of exposure; therefore, these laws should be expanded to include other forms of vaping and should include private properties (eg, cars) for meaningful reduction in SHSe among vulnerable populations (eg, young children). The primary limitation of the study is the potential nonresponse bias in the NHANES data collection, although our study is survey weighted to account for the nonresponse.
Accepted for Publication: July 5, 2020.
Published Online: November 23, 2020. doi:10.1001/jamainternmed.2020.3975
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Shastri SS et al. JAMA Internal Medicine.
Corresponding Authors: Surendra S. Shastri, MD (firstname.lastname@example.org); and Sanjay Shete, PhD (email@example.com), The University of Texas MD Anderson Cancer Center, 1400 Pressler St, Pickens Academic Tower, Houston, TX 77030.
Author Contributions: Drs Talluri and Shete had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Shastri, Shete.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: All authors.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Talluri.
Obtained funding: Shete.
Administrative, technical, or material support: Talluri, Shete.
Supervision: Shastri, Shete
Conflict of Interest Disclosures: None reported.
Funding/Support: This study was supported by the National Cancer Institute (5P30CA016672, Drs Shastri and Shete), a Cancer Prevention and Research Institute of Texas grant award (RP170259, Dr Shete), the Betty B. Marcus Chair in Cancer Prevention (Dr Shete), and the Duncan Family Institute for Cancer Prevention and Risk Assessment (Dr Shete).
Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
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