Differences in rates of obstructive lung disease between Africans and African Americans

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Objective: The prevalence of obstructive lung disease is rising in the United States, particularly among those of African descent. Rates of ventilatory impairment and reported respiratory symptoms were examined in a cross-sectional study of urban Nigerian civil servants who are in transition to a westernized lifestyle. Design: 410 civil servants (235 men, 175 women) aged 30-69 years in Benin City, Nigeria (West Africa) were recruited for a cross-sectional study on respiratory health and compared to 3,397 African Americans enrolled in NHANES III between 1988 and 1994. Methods: Forced vital capacity (FVC), expiratory flow rate in 1 sec (FEV1), FEV1/FVC ratio, and peak expiratory flow rate (PEFR) were measured by spirometry. Demographic characteristics and respiratory symptoms were ascertained by questionnaire. Results: Nigerians had lower age and height adjusted FVC and FEV1 than African Americans in both genders, independent of smoking and respiratory disease. However, relative lung function was better among Nigerians. Fewer Nigerians had an age-adjusted FEV1/FVC ratio below 0.70 than African Americans (10.54 vs 14.10/100 men, 6.29 vs 8.67/100 women). Overall, Nigerians had a lower age-adjusted prevalence of any self-reported respiratory symptoms than African Americans (3.65 vs 22.90/100 men, 4.57 vs 35.38/100 women). Similarly, Nigerians had a lower age-adjusted prevalence of current smoking than African Americans (10.82 vs 46.50/100 in men and 0 vs 30.93/100 in women). Conclusions: Urban Nigerians who have limited exposure to cigarette smoke and who work in a non-industrial setting have a low prevalence of obstructive lung disease.

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