Racial and gender differences in susceptibility to tobacco smoke among patients with chronic obstructive pulmonary disease

Background: Although chronic obstructive pulmonary disease (COPD) has been considered a disease of Caucasian men, recent data show mortality rising faster among women and African-Americans. Some have suggested these groups are more susceptible to tobacco smoke. We examined this issue in our own population of COPD patients. Methods: Beginning in March 2003 we prospectively developed a COPD research database to facilitate recruitment for clinical trials. Enrollees are recruited from clinics and paid advertising and their demographics, medical/smoking histories, and spirometric data are recorded. We examined the smoking histories and pulmonary function of enrollees over 45, with >= 20 pack-years of smoking, FEV1/FVC (forced expiratory volume forced vital capacity) < 0.70, and a race-adjusted post-bronchoditator FEV1 < 80%. The primary outcome was the toss of lung function per pack-year smoked, or Susceptibility Index (SI), calculated using the formula: (% predicted FEV1-100)/pack-years. Results: A total of 585 patients enrolled during the study period and 330 met our inclusion criteria. Caucasians were older than African-Americans (63 vs. 58, P = 0.0003) and had more pack-years of smoking (57 vs. 43, P = 0.0003). There were no differences in lung function or bronchodilator reversibility among the racial or gender subgroups. Caucasians had less loss of lung function per pack-year smoked than African-Americans (SI = -1.02% vs. -1.34%, P = 0.007) and men less than women (SI = -0.98% vs. -1.21%, P = 0.001). Caucasian mates appeared relatively protected from tobacco smoke (SI = -0.93%), while African-American women appeared most susceptible (SI = -1.42%). Conclusions: There are important differences in racial and gender susceptibility to tobacco smoke among patients with COPD. African-American females appear to be at highest risk and may benefit most from smoking cessation. (c) 2005 Elsevier Ltd. All rights reserved.