Re: Contribution of smoking and air pollution in urban areas to social differences in respiratory health
Adamson Sinjani Muula, Department of Community Health, University of Malawi, College of Medicine, Blantyre, Malawi
16 July 2008
The paper by Schikowski et al [1] adds to the literature on pulmonary health, its determinants and possible public health intervention aimed at reducing morbidity and mortality. Among the many findings, the authors reported that “women with low education were more likely to suffer from respiratory symptoms and had reduced lung function.” All throughout the paper, the authors seems to be using the term “socioeconomic status” as synonymous to “education level” attained.
While Schikowski et al chose to refer to education as a measure of socioeconomic status, readers also need to appreciate that the term (socioeconomic status) is a global term that refers to many other things other education. Certainly, education level as a research variable may be easier to collect than income, wealth and neighborhood characteristics. The ease of collection of the education variables may however come at a cost i.e. education may not be the “right” measure of socioeconomic status for a particular research question. This brings us to the second issue i.e. what was the researchers’ hypothesized mechanism of how socioeconomic status should matter in the research they reported? If one takes the life course approach, less educated adults are likely to have grown up in deprived homes and lower parental socioeconomic status is associated with reduced lung functioning in adulthood? [2,3]. So, it is possible that the reduced lung function that we are seeing now among low status women may also be a function of childhood failure to develop lung function fully?
Data are available to suggest that education attained may influence employability in adulthood and/or the income that an individual or family earns. But if the research question would be better answered by our knowing how much income one earns, then we would better ask about income and not education. But income is difficult to collect as people are, in general more sensitive in keeping their income private than their level of education. So we may be satisfied with measuring education anyway. Education level can also be a surrogate measure of cognitive functioning. Educated people may be more likely to understand health messages or make decisions towards health more than the less educated. This aspect of education probably was not a focus of this study.
It is interesting that Schikowski et al [1] chose to analyse education as a categorical variable i.e. less than 10 years of education, 10 years of education and >10 years. It would have been informative if a sensitivity analysis were done to compare the findings when education was analysed as a continuous variable and when different cut-off point were used in the categorical analysis i.e. would the effect estimates change if the variable was binary, or cut off point was at 5 years of education?
In the conclusion, the authors identified the “low status” of people as an important risk factor “for developing respiratory diseases.” Pollution in environments that low status people live is probably the mechanism that would have to be tackled. But can we also suggest ways in order to promote education? May be in younger people? How are we going to do it? Furthermore, is it because the dwellings that los status people are rented, cheap and there is limited political organization and lobbying that pollution from nearby highways go unabated? These may be important questions to explore.
Competing interest
I declare I have no competing interest.
References
1. Schikowski T, Sugiri D, Reimann V, Pesch B, Ranft U, Krämer U: Contribution of smoking and air pollution exposure in urban areas to social differences in respiratory health. BMC Public Health. 2008, 8:179.
2. Jackson B, Kubzansky LD, Cohen S, Weiss S, Wright RJ; CARDIA Study: A matter of life and breath: childhood socioeconomic status is related to young adult pulmonary function in the CARDIA study. Int J Epidemiol. 2004, 33:271-8.
3. Harper S, Lynch J, Hsu WL, Everson SA, Hillemeier MM, Raghunathan TE, Salonen JT, Kaplan GA: Life course socioeconomic conditions and adult psychosocial functioning. Int J Epidemiol. 2002, 31:395-403
Re: Contribution of smoking and air pollution in urban areas to social differences in respiratory health
16 July 2008
The paper by Schikowski et al [1] adds to the literature on pulmonary health, its determinants and possible public health intervention aimed at reducing morbidity and mortality. Among the many findings, the authors reported that “women with low education were more likely to suffer from respiratory symptoms and had reduced lung function.” All throughout the paper, the authors seems to be using the term “socioeconomic status” as synonymous to “education level” attained.
While Schikowski et al chose to refer to education as a measure of socioeconomic status, readers also need to appreciate that the term (socioeconomic status) is a global term that refers to many other things other education. Certainly, education level as a research variable may be easier to collect than income, wealth and neighborhood characteristics. The ease of collection of the education variables may however come at a cost i.e. education may not be the “right” measure of socioeconomic status for a particular research question. This brings us to the second issue i.e. what was the researchers’ hypothesized mechanism of how socioeconomic status should matter in the research they reported? If one takes the life course approach, less educated adults are likely to have grown up in deprived homes and lower parental socioeconomic status is associated with reduced lung functioning in adulthood? [2,3]. So, it is possible that the reduced lung function that we are seeing now among low status women may also be a function of childhood failure to develop lung function fully?
Data are available to suggest that education attained may influence employability in adulthood and/or the income that an individual or family earns. But if the research question would be better answered by our knowing how much income one earns, then we would better ask about income and not education. But income is difficult to collect as people are, in general more sensitive in keeping their income private than their level of education. So we may be satisfied with measuring education anyway. Education level can also be a surrogate measure of cognitive functioning. Educated people may be more likely to understand health messages or make decisions towards health more than the less educated. This aspect of education probably was not a focus of this study.
It is interesting that Schikowski et al [1] chose to analyse education as a categorical variable i.e. less than 10 years of education, 10 years of education and >10 years. It would have been informative if a sensitivity analysis were done to compare the findings when education was analysed as a continuous variable and when different cut-off point were used in the categorical analysis i.e. would the effect estimates change if the variable was binary, or cut off point was at 5 years of education?
In the conclusion, the authors identified the “low status” of people as an important risk factor “for developing respiratory diseases.” Pollution in environments that low status people live is probably the mechanism that would have to be tackled. But can we also suggest ways in order to promote education? May be in younger people? How are we going to do it? Furthermore, is it because the dwellings that los status people are rented, cheap and there is limited political organization and lobbying that pollution from nearby highways go unabated? These may be important questions to explore.
Competing interest
I declare I have no competing interest.
References
1. Schikowski T, Sugiri D, Reimann V, Pesch B, Ranft U, Krämer U: Contribution of smoking and air pollution exposure in urban areas to social differences in respiratory health. BMC Public Health. 2008, 8:179.
2. Jackson B, Kubzansky LD, Cohen S, Weiss S, Wright RJ; CARDIA Study: A matter of life and breath: childhood socioeconomic status is related to young adult pulmonary function in the CARDIA study. Int J Epidemiol. 2004, 33:271-8.
3. Harper S, Lynch J, Hsu WL, Everson SA, Hillemeier MM, Raghunathan TE, Salonen JT, Kaplan GA: Life course socioeconomic conditions and adult psychosocial functioning. Int J Epidemiol. 2002, 31:395-403
Competing interests
None declared