Prometheus 6

Smokers used to get warnings about emphysema and bronchitis. Nowadays we get warned about Chronic Obstructive Pulmonary Disease or COPD, but it's the same thing with a sexier name.

This research (the full report of which hides behind a free registration to MedScape) was an attempt to understand why there are fewer COPD cases per hundred among Black folks than among white folks.

Wissam M. Chatila, MD, FCCP; Walter A. Wynkoop, MD; Gwendolyn Vance, RN; Gerard J. Criner, MD, FCCP
CHEST 125(1):15-21, 2004. © 2004 American College of Chest Physicians
Posted 01/28/2004

Abstract and Introduction

Abstract

Background: The prevalence and mortality associated with COPD increases with age, with higher rates observed in whites than African Americans. Causes and explanations for smoking-related racial differences on the respiratory system have not been determined.
Objective: To investigate racial differences in smoking patterns and lung function in patients with advanced COPD.

Design: Retrospective record review of patients with advanced COPD.

Setting: Outpatient pulmonary clinic in a tertiary-care urban hospital.

Patients: One hundred sixty patients with advanced COPD (80 African Americans and 80 whites) referred for either lung volume reduction surgery or transplantation evaluation.

Data Collection: Demographics, smoking profile, pulmonary function testing, arterial blood gases, and exercise stress tests were compared between African-American and white patients.

Results: Despite comparable pulmonary function, African Americans were younger at presentation and had lower overall pack-years of smoking than whites (58 ± 10 years vs 62 ± 8 years, and 44 ± 23 pack-years vs 66 ± 31 pack-years, respectively; p < 0.05 [mean ± SD]). Additionally, African Americans started smoking later in life than whites (18 ± 5 years vs 16 ± 4 years). Similarly, women presented at a younger age and smoked less compared to men (58 ± 9 years vs 62 ± 9 years, and 49 ± 28 pack-years vs 61 ± 29 pack-years, respectively; p < 0.05), without showing any difference in lung function or exercise performance.

Conclusion: Among susceptible patients with advanced COPD, African Americans and women seem more prone to the effects of tobacco smoke than their counterparts.

Introduction

Despite narrowing differences in smoking patterns between races and genders,^[1,2] the prevalence of COPD remains higher in whites than in African Americans, and in men than women.^[3] In addition, whites and men continue to have higher mortality rates than African Americans and women; however, both latter groups appear to be catching up to their counterparts.^[3] In 1962, Murphy and colleagues^[4] were the first to suggest that COPD is a disease of the "white male." Since then, many large epidemiologic surveys^[3,5] have confirmed that the prevalence and attributable mortality in COPD is greater in whites and men. Despite these observations, population-based studies have not shown a difference in the rates of decline in FEV₁ between African Americans and whites when adjusted for pack-years of smoking.^[6] A limitation of these population-based studies is the observation that only 10 to 15% of regular smokers acquire COPD. To our knowledge, no studies have examined racial differences in cigarette smoking exposure in a group of susceptible smokers.

Possible explanations for smoking-related racial differences on the respiratory system are currently obscure. Previously published epidemiologic studies^[3,6] do not discriminate whether the observed differences are due to genetic differences in susceptibility to smoking, or other confounding factors such as differences in smoking behavior (debut, amount, duration), environmental exposure, or physiologic differences (eg, smaller lung volumes). More importantly, selection and survivor effects could bias estimated COPD racial prevalences. Smaller numbers of African Americans in studies,^[7] which in part may be due to their greater attrition from the increased smoking-related cardiovascular/cancer mortality, might have lead to an underestimation of the prevalence of COPD and, thus, to the observed wider racial gap.

If the higher COPD prevalence rates found in whites compared to African Americans are secondary to whites being more susceptible to the adverse effects of cigarette smoking, then one would expect whites to have more severe COPD. At our center, however, which treats a relatively large number of African-American patients with COPD, our experience indicates that African Americans present with as severe manifestations of COPD as their white counterparts. Accordingly, we performed a retrospective review of medical records of patients with advanced COPD referred to our urban teaching hospital with the aim to investigate racial differences in smoking patterns and lung function.