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Racial differences found in emphysema onset

July 11, 2006

Although African Americans smoke fewer cigarettes and inhale them less deeply than Caucasians, they contract emphysema at an earlier age, according to a study by Temple University researchers in the journal Chest.

The study, which confirms findings from a smaller preliminary study published last year, also offers evidence of biological differences in the distribution of emphysema and the severity of lung destruction between African Americans and Caucasians, leading researchers to conclude that the mechanism underlying the disease might also vary between the races.

"Not everyone who smokes gets emphysema or the same type of emphysema," says Wissam Chatila, MD, lead author and associate professor of medicine at Temple University School of Medicine and Hospital. "Our study supports previous findings that there might be something different between African Americans and Caucasians who are susceptible to the bad effects of smoking. The next question — why is this so?"

While researchers begin to tackle this puzzle, Chatila notes that the current study contains important implications for primary care doctors of African American patients. By identifying the disease early and avoiding misdiagnosis, patients can receive better treatments and achieve improved outcomes. Along with an understanding of how severe emphysema develops, the work may also aid in shaping antismoking policies and smoking cessation programs that specifically target African Americans.

"If African American patients are smoking and suffering some degree of breathing disturbances, the study shows that we need to pay better attention, even if they seem too young to have emphysema," said Chatila, who is also a pulmonary specialist at the Temple Lung Center.

Confirmation of earlier findings on racial biological differences was important because of understandable skepticism about such distinctions.

"People question whether racial differences in disease are due to factors such as the environment, socioeconomic status or health care disparities," says Chatila.

The researchers acknowledge that such issues may play an important part in the development and onset of the disease and further, that a much higher proportion of African Americans will need to be studied before resolving issues of race and environment that might influence emphysema risks and outcomes.

The Temple team examined 1198 patients with severe or very severe emphysema who were enrolled in the National Emphysema Treatment Trail (NETT). Severity, distribution and physiologic impact of emphysema in both groups were determined using cardiopulmonary function tests, quantitative computed tomography (CT) of the chest, and a quality of life questionnaire.

Forty-two participants were African Americans (3.4%), compared to 1156 (95%) Caucasians. However, when matched in respect to age, height, smoking and pulmonary function, researchers were still surprised to find differences in how the disease progressed in the two races, in particular that African Americans were younger and smoked less than whites.

The report notes that while "few doubt the answer lies in the complex genotype- environment interaction, the extent to which each factor plays a role in the development of emphysema remains enigmatic."

Chatila, whose interest in this area of research originated when he and his colleagues noticed that African American patients were presenting with chronic obstructive pulmonary disease (COPD) that was often under treated and misdiagnosed, has already begun to explore the cellular differences and inflammation in patients with emphysema to see if these can explain some of the differences observed in the study.

Temple University