The prevalence of COPD is known to be different between African Americans and whites. Murphy et al and Massaro et al were the first to suggest that COPD is a disease of white men rather than African Americans. Large epidemiologic surveys confirmed that COPD is the only smoking-related disease in which the prevalence and mortality are higher in white patients than African-American patients (prevalence, 6.3% vs 3.9% for chronic bronchitis, 3.5% vs 1% for emphysema, and mortality rates of 47/ 100,000 vs 21/100,000; respectively). In addition to smoking, the recent executive summary of the Global Initiative for Chronic Obstructive Lung Disease highlights the role of airway hyperresponsiveness and low socioeconomic status as risk factors for the development of COPD. Interestingly, all three factors are more prevalent in African Americans; paradoxically, COPD is more common in white patients. www.storehealthmall.eu
Epidemiologic studies fail to explain whether the observed racial differences are due to genetic differences in susceptibility to smoking; physiologic differences between the races (eg, variability of lung volumes); confounding factors such as differences in smoking behavior (debut, amount, duration); environmental exposure; or to sampling of the patient population. Selection and survivor effects could potentially bias the estimates of COPD prevalence rates in favor of the white population. For example, smaller numbers of African Americans in studies and surveys, which may in part be due to increased smoking-related cardiovascular/cancer mortality, could lead to underestimation of their relative risks, thereby contributing to the observed racial gap.
There are no studies that have characterized the severity and nature of chronic obstructive airway diseases, particularly with respect to the presence and magnitude of emphysema in the different racial groups. One possibility is that if white subjects were more susceptible to smoking, they would not only have a higher prevalence of COPD but also more severe COPD, or an earlier presentation than African Americans. This was not found in a retrospective study of racial differences in COPD patients being evaluated for surgical intervention; although African Americans were similarly affected, they smoked less, began smoking later in life and, more importantly, presented with symptoms at a younger age than did whites. Moreover, a gender/race meta-analysis by Vollmer and colleagues of eight large population-based studies failed to demonstrate a difference in the rate of smoking-related decline in lung function between African-American and white populations.