New Research Suggests Education Level Affects Lung Function
Madison, Wisconsin - A new study led by University of Wisconsin-Madison researchers shows that the affects of poverty, including a lower education level, may explain why African-Americans tend to have a lower lung capacity and thus more breathing problems.
The findings challenge current research assumptions holding that race itself explains impaired lung function in African-Americans and some other racial groups.
Dr. David Van Sickle, an asthma researcher affiliated with the Department of Population Health Sciences in the UW School of Medicine and Public Health, says that he has long been puzzled by national norms that assume that African-Americans have a lower "normal" lung capacity, which is measured by forced expiratory volume (FEV) and is generally lower in people with asthma.
"When you think about it, why would lung function be determined by skin color?" he says.
The UW researchers, including Dr. John Mullahy, professor of population health sciences at the UW School of Medicine and Public Health, decided to take a closer look at the connection. They used a statistical method known as quantile regression to study the health records of 9,653 people who took part in the National Health and Nutrition Examination Survey (NHANES III).
"Seemingly subtle issues in how samples are constructed and data are analyzed ultimately have important implications for how we understand the roles of race and socioeconomic status as determinants of respiratory health," says Mullahy.
The researchers decided to compare lung function and high school graduation rates, because dropping out of high school is associated with poverty.
"We found that if you finish high school, there is significant beneficial effect to lung function," Van Sickle says. "We've been attributing poor normal lung function to a racial effect, when in fact, what we're seeing in large part appears to be the accumulated impact of socioeconomic factors."
For example, the article highlights how early life exposures to poor nutrition and environmental tobacco smoke limit the growth and development of lung size and lead to a more rapid decline with age.
Previous studies used to determine normal lung function values have also excluded smokers. But because smoking tobacco is also associated with poverty, that meant that poorer people were left out of studies that set norms for lung function.
The study, published in the current American Journal of Respiratory and Critical Care Medicine, also warranted an editorial.
"The importance of the present study is as much in the conceptual basis of how experimental subject groups need to be carefully chosen to allow reliable answers," the editorial said. "At the end of the day, socioeconomic status appears to be an independent (and under-recognized) factor separate from race."
Van Sickle says the findings support the need for a critical reappraisal of the national norms for asthma and lung function, something that has happened in other areas of medicine.
Years ago, pediatricians had separate growth charts for children of different races, showing that black children weren't expected to grow as rapidly as white children. Later research showed the differences were due to poverty, not race, and resulted in a landmark 1981 article in The Lancet entitled "Measuring Children: One Reference for All."
Van Sickle and a third co-author on the paper, Dr. Sheryl Magzamen, of the University of Oklahoma, are former Health and Society Scholars at the University of Wisconsin-Madison, a program supported by the Robert Wood Johnson Foundation.
Date Published: 09/14/2011