Downloaded from http://tobaccocontrol.bmj.com/ on November 17, 2015 - Published by group.bmj.com
Research paper
Socioeconomic disparities in secondhand smoke exposure among US never-smoking adults: the National Health and Nutrition Examination Survey 1988–2010 Wen Qi Gan,1,2,3 David M Mannino,1 Ahmedin Jemal4 ▸ Additional material is published online only. To view please visit the journal online (http://dx.doi.org/10.1136/ tobaccocontrol-2014-051660). 1
Department of Preventive Medicine and Environmental Health, University of Kentucky College of Public Health, Lexington, Kentucky, USA 2 Department of Population Health, Hofstra North Shore-LIJ School of Medicine, Great Neck, New York, USA 3 Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Great Neck, New York, USA 4 Surveillance and Health Services Research, American Cancer Society, Inc, Atlanta, Georgia, USA Correspondence to Dr Wen Qi Gan, Department of Preventive Medicine and Environmental Health, University of Kentucky College of Public Health, 111 Washington Avenue, Suite 220, Lexington, KY 40536, USA; [email protected] Received 5 March 2014 Accepted 13 June 2014 Published Online First 11 July 2014
ABSTRACT Background Secondhand smoke (SHS) is a leading preventable cause of illness, disability and mortality. There is a lack of quantitative analyses on socioeconomic disparities in SHS; especially, it is not known how socioeconomic disparities have changed in the past two decades in the USA. Objectives To examine socioeconomic disparities and long-term temporal trends in SHS exposure among US never-smoking adults aged ≥20 years. Methods 15 376 participants from the National Health and Nutrition Examination Survey (NHANES) 1999–2010 were included in the analysis of socioeconomic disparities; additional 8195 participants from NHANES III 1988–1994 were included in the temporal trend analysis. SHS exposure was assessed using self-reported exposure in the home and workplace as well as using serum cotinine concentrations ≥0.05 ng/mL. Individual socioeconomic status (SES) was assessed using povertyto-income ratio. Results During the period 1999–2010, 6% and 14% of participants reported SHS exposure in the home and workplace, respectively; 40% had serum cotinineindicated SHS exposure. Individual SES was strongly associated with SHS exposure in a dose–response fashion; participants in the lowest SES group were 2–3 times more likely to be exposed to SHS compared with those in the highest SES group. During the period 1988–2010, the prevalence declined over 60% for the three types of SHS exposure. However, for cotinineindicated exposure, the magnitudes of the declines were smaller for lower SES groups compared with higher SES groups, leading to widening socioeconomic disparities in SHS exposure. Conclusions SHS exposure is still widespread among US never-smoking adults, and socioeconomic disparities for cotinine-indicated exposure have substantially increased in the past two decades.
INTRODUCTION
To cite: Gan WQ, Mannino DM, Jemal A. Tob Control 2015;24:568–573. 568
Secondhand smoke (SHS) is a complex mixture of gases and fine particles generated from the burning end of a tobacco product such as a cigarette as well as exhaled by active smokers.1 2 It is also known as passive smoke, involuntary smoke and environmental tobacco smoke. In the USA, the most common source of SHS is cigarettes, followed by pipes, cigars and other tobacco products.1 Tobacco smoke contains more than 7000 chemicals, at least 250 are known to be toxic, about 70 are known to cause cancer.2 Inhaling SHS can cause serious
health problems in non-smokers such as respiratory and cardiovascular diseases, and there is no safe level of exposure.1–7 The US Surgeon General estimates that for non-smoking adults who inhale SHS, the risk of lung cancer increases 20–30%, and the risk of heart disease increases 25–30%1; each year approximately 7330 and 33 950 US non-smoking adults die from lung cancer and coronary heart disease, respectively, because of inhaling SHS.3 SHS is a leading preventable cause of illness, disability and mortality in the USA and worldwide. Active cigarette smoking is strongly associated with individual socioeconomic status (SES); persons with lower SES are more likely to smoke cigarettes and other tobacco products.3 8–10 It is therefore plausible that non-smokers with lower SES are more likely to be exposed to SHS. Many previous studies reported socioeconomic disparities in SHS exposure among children11–16 and nonsmoking adults.17–23 However, there is a lack of quantitative analyses on this issue in the USA17–19; especially it is not known how socioeconomic disparities in SHS exposure have changed in the past two decades. Furthermore, it has been reported that SHS exposure has been declining in the USA19 24; however, it is not clear whether SHS exposure has been equally declined for people from different SES groups. Therefore, we conducted this study to examine socioeconomic disparities and their long-term temporal trends in SHS exposure among never-smoking adults in the USA.
METHODS Study design and participants The National Health and Nutrition Examination Survey (NHANES) is a series of cross-sectional surveys to assess the health and nutrition status of the US population. During each survey, a nationally representative sample of the civilian noninstitutionalised population was selected using a complex, stratified, multistage probability sampling procedure. The survey included a household interview and a subsequent medical examination. During the household interview, various health-related questionnaires were administered by trained interviewers. During the medical examination, blood samples were collected for various laboratory measurements.25 In accordance with the National Center for Health Statistics (NCHS) analytic guidelines,26 we aggregated all available NHANES data from 1999 to 2010 to create a large combined data set.
Gan WQ, et al. Tob Control 2015;24:568–573. doi:10.1136/tobaccocontrol-2014-051660
Downloaded from http://tobaccocontrol.bmj.com/ on November 17, 2015 - Published by group.bmj.com
Research paper Never-smokers 20 years of age and older were selected for the analyses of the relationship between individual SES and SHS exposure. In the temporal trend analysis on the prevalence of SHS exposure, phase 1 (1988–1991) and phase 2 (1991–1994) of NHANES III data were also included to describe long-term temporal trends of SHS exposure. Informed consent was obtained from all participants.
Assessment of exposure to SHS The current study was restricted to never-smoking adults, who had not smoked more than 100 cigarettes in their lifetime. Self-reported exposure in the home: For NHANES 1999– 2010, SHS exposure in the home was defined as never-smoking adults who answered ‘yes’ to the question: “Does anyone who lives here smoke cigarettes, cigars, or pipes anywhere inside this home?” For NHANES III 1988–1994, it was defined as neversmoking adults who reported that any household members smoked cigarettes inside their homes. Self-reported exposure in the workplace: For NHANES 1999– 2010, SHS exposure in the workplace was defined as neversmoking adults who “can smell the smoke from other people’s cigarettes, cigars, or pipes” in the workplace. For NHANES III 1988–1994, it was defined as never-smoking adults who could smell other people’s smoking in the workplace at least 1 h/day. Serum cotinine-indicated exposure: Serum cotinine is a valid biomarker for SHS exposure, and has been widely used to measure SHS exposure in epidemiological studies.27–29 Based on the previous studies,1 24 never-smoking adults who had a serum cotinine concentration ≥0.05 ng/mL were regarded as exposed to SHS. In NHANES III 1988–1994 and NHANES 1999–2010, serum cotinine was measured by a highperformance liquid chromatography/atmospheric pressure ionisation tandem mass spectrometry (LC/MS/MS). This method has been described in detail elsewhere.30 31
Socioeconomic status Poverty-to-income ratio (PIR) was used to measure each person’s SES. The PIR is the ratio of annual household income to the family’s corresponding poverty threshold published by the US Census Bureau in a given calendar year.32 PIR values ≥1 indicate participants living at or above the federal poverty level, whereas PIR values
Research paper
Socioeconomic disparities in secondhand smoke exposure among US never-smoking adults: the National Health and Nutrition Examination Survey 1988–2010 Wen Qi Gan,1,2,3 David M Mannino,1 Ahmedin Jemal4 ▸ Additional material is published online only. To view please visit the journal online (http://dx.doi.org/10.1136/ tobaccocontrol-2014-051660). 1
Department of Preventive Medicine and Environmental Health, University of Kentucky College of Public Health, Lexington, Kentucky, USA 2 Department of Population Health, Hofstra North Shore-LIJ School of Medicine, Great Neck, New York, USA 3 Feinstein Institute for Medical Research, North Shore-Long Island Jewish Health System, Great Neck, New York, USA 4 Surveillance and Health Services Research, American Cancer Society, Inc, Atlanta, Georgia, USA Correspondence to Dr Wen Qi Gan, Department of Preventive Medicine and Environmental Health, University of Kentucky College of Public Health, 111 Washington Avenue, Suite 220, Lexington, KY 40536, USA; [email protected] Received 5 March 2014 Accepted 13 June 2014 Published Online First 11 July 2014
ABSTRACT Background Secondhand smoke (SHS) is a leading preventable cause of illness, disability and mortality. There is a lack of quantitative analyses on socioeconomic disparities in SHS; especially, it is not known how socioeconomic disparities have changed in the past two decades in the USA. Objectives To examine socioeconomic disparities and long-term temporal trends in SHS exposure among US never-smoking adults aged ≥20 years. Methods 15 376 participants from the National Health and Nutrition Examination Survey (NHANES) 1999–2010 were included in the analysis of socioeconomic disparities; additional 8195 participants from NHANES III 1988–1994 were included in the temporal trend analysis. SHS exposure was assessed using self-reported exposure in the home and workplace as well as using serum cotinine concentrations ≥0.05 ng/mL. Individual socioeconomic status (SES) was assessed using povertyto-income ratio. Results During the period 1999–2010, 6% and 14% of participants reported SHS exposure in the home and workplace, respectively; 40% had serum cotinineindicated SHS exposure. Individual SES was strongly associated with SHS exposure in a dose–response fashion; participants in the lowest SES group were 2–3 times more likely to be exposed to SHS compared with those in the highest SES group. During the period 1988–2010, the prevalence declined over 60% for the three types of SHS exposure. However, for cotinineindicated exposure, the magnitudes of the declines were smaller for lower SES groups compared with higher SES groups, leading to widening socioeconomic disparities in SHS exposure. Conclusions SHS exposure is still widespread among US never-smoking adults, and socioeconomic disparities for cotinine-indicated exposure have substantially increased in the past two decades.
INTRODUCTION
To cite: Gan WQ, Mannino DM, Jemal A. Tob Control 2015;24:568–573. 568
Secondhand smoke (SHS) is a complex mixture of gases and fine particles generated from the burning end of a tobacco product such as a cigarette as well as exhaled by active smokers.1 2 It is also known as passive smoke, involuntary smoke and environmental tobacco smoke. In the USA, the most common source of SHS is cigarettes, followed by pipes, cigars and other tobacco products.1 Tobacco smoke contains more than 7000 chemicals, at least 250 are known to be toxic, about 70 are known to cause cancer.2 Inhaling SHS can cause serious
health problems in non-smokers such as respiratory and cardiovascular diseases, and there is no safe level of exposure.1–7 The US Surgeon General estimates that for non-smoking adults who inhale SHS, the risk of lung cancer increases 20–30%, and the risk of heart disease increases 25–30%1; each year approximately 7330 and 33 950 US non-smoking adults die from lung cancer and coronary heart disease, respectively, because of inhaling SHS.3 SHS is a leading preventable cause of illness, disability and mortality in the USA and worldwide. Active cigarette smoking is strongly associated with individual socioeconomic status (SES); persons with lower SES are more likely to smoke cigarettes and other tobacco products.3 8–10 It is therefore plausible that non-smokers with lower SES are more likely to be exposed to SHS. Many previous studies reported socioeconomic disparities in SHS exposure among children11–16 and nonsmoking adults.17–23 However, there is a lack of quantitative analyses on this issue in the USA17–19; especially it is not known how socioeconomic disparities in SHS exposure have changed in the past two decades. Furthermore, it has been reported that SHS exposure has been declining in the USA19 24; however, it is not clear whether SHS exposure has been equally declined for people from different SES groups. Therefore, we conducted this study to examine socioeconomic disparities and their long-term temporal trends in SHS exposure among never-smoking adults in the USA.
METHODS Study design and participants The National Health and Nutrition Examination Survey (NHANES) is a series of cross-sectional surveys to assess the health and nutrition status of the US population. During each survey, a nationally representative sample of the civilian noninstitutionalised population was selected using a complex, stratified, multistage probability sampling procedure. The survey included a household interview and a subsequent medical examination. During the household interview, various health-related questionnaires were administered by trained interviewers. During the medical examination, blood samples were collected for various laboratory measurements.25 In accordance with the National Center for Health Statistics (NCHS) analytic guidelines,26 we aggregated all available NHANES data from 1999 to 2010 to create a large combined data set.
Gan WQ, et al. Tob Control 2015;24:568–573. doi:10.1136/tobaccocontrol-2014-051660
Downloaded from http://tobaccocontrol.bmj.com/ on November 17, 2015 - Published by group.bmj.com
Research paper Never-smokers 20 years of age and older were selected for the analyses of the relationship between individual SES and SHS exposure. In the temporal trend analysis on the prevalence of SHS exposure, phase 1 (1988–1991) and phase 2 (1991–1994) of NHANES III data were also included to describe long-term temporal trends of SHS exposure. Informed consent was obtained from all participants.
Assessment of exposure to SHS The current study was restricted to never-smoking adults, who had not smoked more than 100 cigarettes in their lifetime. Self-reported exposure in the home: For NHANES 1999– 2010, SHS exposure in the home was defined as never-smoking adults who answered ‘yes’ to the question: “Does anyone who lives here smoke cigarettes, cigars, or pipes anywhere inside this home?” For NHANES III 1988–1994, it was defined as neversmoking adults who reported that any household members smoked cigarettes inside their homes. Self-reported exposure in the workplace: For NHANES 1999– 2010, SHS exposure in the workplace was defined as neversmoking adults who “can smell the smoke from other people’s cigarettes, cigars, or pipes” in the workplace. For NHANES III 1988–1994, it was defined as never-smoking adults who could smell other people’s smoking in the workplace at least 1 h/day. Serum cotinine-indicated exposure: Serum cotinine is a valid biomarker for SHS exposure, and has been widely used to measure SHS exposure in epidemiological studies.27–29 Based on the previous studies,1 24 never-smoking adults who had a serum cotinine concentration ≥0.05 ng/mL were regarded as exposed to SHS. In NHANES III 1988–1994 and NHANES 1999–2010, serum cotinine was measured by a highperformance liquid chromatography/atmospheric pressure ionisation tandem mass spectrometry (LC/MS/MS). This method has been described in detail elsewhere.30 31
Socioeconomic status Poverty-to-income ratio (PIR) was used to measure each person’s SES. The PIR is the ratio of annual household income to the family’s corresponding poverty threshold published by the US Census Bureau in a given calendar year.32 PIR values ≥1 indicate participants living at or above the federal poverty level, whereas PIR values
