Effect of smoking on spirometry of African American and White subjects.
BACKGROUND
Smoking is the single most important risk factor for COPD, yet there is still disagreement about the differences in the effect of smoking between white and African-American people. We hypothesized that the results of spirometry between smokers of the two races are equivalent if reference equations and lower limits of normal appropriate for each race are used.


METHODS
We retrospectively analyzed all spirometry results in smokers over a 1-year period from the G.V. (Sonny) Montgomery VA Medical Center and excluded those that did not meet American Thoracic Society standards, or those from patients with additional medical problems. The remaining patients were classified by race and then matched for age and smoking history; 108 patients in each group were included, which met the power analysis goal of 98. The two groups were similar in age (57.5 years vs 57.0 years), smoking history (46.1 pack-years vs 46.0 pack-years), and body mass index (27.0 kg/m(2) vs 28.3 kg/m(2)) for African Americans and whites, respectively. Data were analyzed using the unpaired t test, and p values were adjusted for multiple comparisons using the Bonferroni factor.


RESULTS
There were statistically significant differences between African American and white smokers in FVC (3.67 +/- 0.07 L vs 4.26 +/- 0.08 L, p = 0.001) and FEV(1) (2.33 +/- 0.07 L vs 2.72 +/- 0.08 L, p = 0.002), as expected from the normal populations; however, there were no differences in FVC as percentage of predicted (89.1 +/- 1.3% vs 86.7 +/- 1.5%, p = 0.71) and FEV(1) as percentage of predicted (71.9 +/- 2.1% vs 72.2 +/- 1.8%, p = 1.00) when the reference equations appropriate for race were used (third National Health and Nutrition Examination Survey). There were also no differences between the number of subject with abnormal FEV(1)/FVC results (56 African Americans vs 58 whites, p = 1.00) when the appropriate lower limits of normal were used.


CONCLUSIONS
There are no differences in spirometry findings between African Americans and whites when abnormality is defined appropriately using reference equations and lower limits of normal for each race. By using either percentage cutoffs for abnormality, or by adjusting for African-American equations only appropriate for whites, we were able to mimic with our data conflicting results in the literature.
Berry
Olivia F
OF
School of Medicine, University of Mississippi Medical Center, Jackson, MS.
Bhagat
Rajesh
R
Division of Pulmonary and Critical Care Medicine, University of Mississippi Medical Center and G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS.
Ajelabi
Akinyinka A
AA
Division of Pulmonary and Critical Care Medicine, University of Mississippi Medical Center and G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS.
Petrini
Marcy F
MF
Division of Pulmonary and Critical Care Medicine, University of Mississippi Medical Center and G.V. (Sonny) Montgomery VA Medical Center, Jackson, MS. Electronic address: mpetrini@medicine.umsmed.edu.
D001741:Black or African American; D015992:Body Mass Index; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012907:Smoking / Q000208:ethnology* / Q000503:physiopathology*; D013147:Spirometry; D014797:Vital Capacity / Q000502:physiology; D044465:White People