title: South African and international reference values for lung function and its relationship with blood pressure in Africans.
abstract: BACKGROUND
  In South Africa respiratory diseases are highly prevalent, with cardiovascular disease being a manifestation. However, international reference values for lung function are commonly used, which may not be appropriate to correctly identify reduced lung function. An inverse relationship exists between lung function and blood pressure (BP) but is not investigated extensively in black South Africans.
  
  
  METHODS
  We included 2010 Africans from the PURE (Prospective Urban Rural Epidemiology) study (aged > 35 years) in the North West Province. Spirometry was performed and predicted values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) were calculated from South African, European and United States prediction equations.
  
  
  RESULTS
  With the exception of the European predicted values, all other predicted mean FEV1 and FVC were above 80%. South African reference values displayed the highest percentages of the predicted values for FEV1 and FVC (87.9 and 99.7%, respectively.) BP increased from quintiles five to one for both FEV1 and FVC, (p for trend <0.001). After adjustment the differences remained (p<0.05).
  
  
  CONCLUSIONS
  South African reference values yielded higher percentages of predicted FEV1 and FVC values than European and US equations suggesting that South African prediction equations may be more useful when investigating lung function in black South Africans. Elevated BP is related to reduced lung function, highlighting the importance in managing both respiratory- and cardiovascular disease.
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: Yolandi
authors: Y
authors: van Rooyen
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: Hugo W
authors: HW
authors: Huisman
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: Aletta E
authors: AE
authors: Schutte
authors: Occupational Hygiene and Health Research Initiative (OHHRI), North-West University, Potchefstroom, South Africa.
authors: Fritz C
authors: FC
authors: Eloff
authors: Occupational Hygiene and Health Research Initiative (OHHRI), North-West University, Potchefstroom, South Africa.
authors: Johan L
authors: JL
authors: Du Plessis
authors: Occupational Hygiene and Health Research Initiative (OHHRI), North-West University, Potchefstroom, South Africa.
authors: Annamarie
authors: A
authors: Kruger
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa. Electronic address: johannes.vanrooyen@nwu.ac.za.
authors: Johannes M
authors: JM
authors: Van Rooyen
mesh_terms: D000328:Adult; D044383:Black People / Q000706:statistics & numerical data*; D002318:Cardiovascular Diseases / Q000208:ethnology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005060:Europe; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000208:ethnology / Q000503:physiopathology; D038622:Internationality; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012016:Reference Values; D012129:Respiratory Function Tests; D012140:Respiratory Tract Diseases / Q000453:epidemiology / Q000503:physiopathology; D013019:South Africa; D013147:Spirometry; D014481:United States; D014797:Vital Capacity / Q000502:physiology*; D044465:White People / Q000706:statistics & numerical data*; D001741:Black or African American
keywords: Cardiovascular disease; Ethnicity; Hypertension; Lung function; Respiratory diseases