Your Family Physician

The ongoing insult of environmental tobacco smoke (ETS) in the home during childhood years can contribute to lower lung function and early emphysema later in life due to mechanical stress to the alveolar wall, even in nonsmokers, according to newly analyzed data from the Multi-Ethnic Study of Arthrosclerosis (MESA) released here at ATS 2009: the American Thoracic Society International Conference.

Smoking leads to emphysema in the upper lobes of the lungs; however, panacinar emphysema involves the complete respiratory lobule and is associated with alpha 1-antitrypsin deficiency. Typically, it develops in patients who have never smoked. To date, other risk factors are unknown.

Dr. Gina Lovasi

"We found a statistically significant difference in subjects who lived in a home with regular smokers and we were somewhat surprised to see a difference that was not due to chance," lead investigator Gina S. Lovasi, PhD, MPH, from the Robert Wood Johnson Foundation Health & Society Scholars program, Institute for Social and Economic Research, Columbia University, in New York City, said during a news conference.

The MESA Lung study (an ancillary study of MESA, which is assessing the role of endothelial dysfunction and genetic susceptibility in subclinical chronic obstructive pulmonary disease) used data and computed tomography scan results, piggybacked from coronary artery scans, from the American multiethnic, multisite MESA cohort study of 1781 nonsmoking cardiovascular disease-free healthy adults, aged 45 to 84 years (mean age, 61 ± 10 years), 65% of whom were female, recruited in 2000 to 2002; follow-up is ongoing. Participants reported having smoked fewer than 100 cigarettes, cigars, or pipes of tobacco in their lifetimes; urinary cotinine levels were less than 100 ng/mL.

Childhood ETS exposure was assessed retrospectively as a report of living with people who smoked regularly in the home. The MESA Lung study used a fractal, structural measure of early emphysema and a standard quantitative measure from the cardiac scans to assess the total volume of air-like space in the lungs and the larger clusters of air-like areas in the lungs.

Subjects who lived their childhood in homes with 2 or more smokers, compared with those who lived with no smokers, had a mean alpha that was 0.04 lower and a mean percent emphysema that was 2.1 (P = .03 and 0.01, respectively) higher after adjustment for age, height, education, demographics, history of residing in air-polluted areas, occupational exposure to irritants, and adult ETS. The mean proportion of air-like space in the lungs was 17% for nonsmokers with no childhood ETS, 18% for nonsmokers who lived with 1 smoker as a child, and 20% for those who lived with 2 or more smokers as a child. Childhood ETS was not associated with lung function in this healthy population, the study reported.

"The difference between the highest and the lowest groups was 3%, but we attenuated that to 2% after statistically accounting for other factors and characteristics," said Dr. Lovasi.

Dr. Phyllis Dennery

Some of the key limitations in the study, Dr. Lovasi pointed out, were that it relied on subjects' reports, and their measure did not allow researchers to document timing or the amount of the exposure. Some characteristics could not be measured, such as nutrition during childhood, which Dr. Lovasi said could explain some of the differences the researchers observed. "Also, we only looked at 1 point in time," she said. "We plan to follow the cohort and document how their lungs change over time."

News conference moderator Phyllis Dennery, MD, FAAP, chief of the Division of Neonatology, Children's Hospital of Philadelphia, and professor of pediatrics at the University of Pennsylvania School of Medicine, said: "It's always of interest to go back and see what has an effect down the road on the impact of disease."

The MESA Lung study is supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. Dr. Lovasi and Dr. Dennery have disclosed no relevant financial relationships.

ATS 2009: American Thoracic Society International Conference: Abstract 280. Presented May 18, 2009.

Source : http://www.medscape.com/viewarticle/703041?sssdmh=dm1.474484&src=nldne