title: Reduced Forced Vital Capacity in an African Population. Prevalence and Risk Factors.
abstract: BACKGROUND
  Black Africans have reduced FVC compared with white persons, but the prevalence and determinants of reduced values are not well understood.
  
  
  OBJECTIVE
  To evaluate the prevalence and factors leading to reduced FVC in a Nigerian population and to examine current theories regarding the determinants of this difference.
  
  
  METHODS
  We studied the ventilatory function of 883 adults aged 40 years or older participating in the Burden of Obstructive Lung Disease Study in Ile-Ife, Nigeria. Respondents completed pre- and post-bronchodilator spirometry test and provided information on their smoking history, respiratory symptoms, risk factors, and diagnoses, including anthropometric details. We used standard categories to define body mass index as either underweight, normal, overweight, or obese. We defined reduced FVC as a post-bronchodilator FVC below the lower limit of normal using National Health and Nutrition Examination Survey (NHANES) equations, Global Lung Function Initiative 2012 equations, and local reference equations based on nonsmoking study participants without a respiratory diagnosis. We fit multivariate linear regression models to FVC as a continuous measure, adjusting for age, sex, height, and other confounders.
  
  
  RESULTS
  The prevalence of reduced FVC was 70.4% for men and 72.8% for women when using NHANES values for white Americans, 17.8% for men and 14.4% for women using NHANES equations for African Americans, and 15.5% for men and 20.5% for women using the Global Lung Function Initiative 2012 equations. Using the equations derived from nonsmoking respondents in the survey without a respiratory diagnosis, the prevalence of reduced FVC was less than 4% for both men and women. FVC was lower in participants who had less than 7 years of education (FVC, -96 ml; 95% confidence interval [CI], -172 to -19), were underweight (FVC, -269 ml; 95% CI, -464 to -73), were overweight (FVC, -132 ml; 95% CI, -219 to -46), and were obese (FVC, -222 ml; 95% CI, -332 to -112).
  
  
  CONCLUSIONS
  There is a wide variation in the prevalence of reduced FVC based on the reference standard used. This variation is not satisfactorily explained by factors thought to affect FVC within individual populations. However, the prevalence strongly associates with both education level and body mass index in this population, regardless of the specific standard used.
authors.affiliation: 1 Department of Medicine, Obafemi Awolowo University, Ile-Ife, Nigeria.
authors.forename: Daniel O
authors.identifier: http://orcid.org/0000-0003-3798-7526
authors.initials: DO
authors.lastname: Obaseki
authors.affiliation: 1 Department of Medicine, Obafemi Awolowo University, Ile-Ife, Nigeria.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Erhabor
authors.affiliation: 1 Department of Medicine, Obafemi Awolowo University, Ile-Ife, Nigeria.
authors.forename: Olayemi F
authors.initials: OF
authors.lastname: Awopeju
authors.affiliation: 1 Department of Medicine, Obafemi Awolowo University, Ile-Ife, Nigeria.
authors.forename: Olufemi O
authors.initials: OO
authors.lastname: Adewole
authors.affiliation: 2 Department of Medicine, Federal Medical Centre, Owo, Nigeria.
authors.forename: Bamidele O
authors.initials: BO
authors.lastname: Adeniyi
authors.affiliation: 3 Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon; and.
authors.forename: Emerita A Sonia
authors.initials: EAS
authors.lastname: Buist
authors.affiliation: 4 Respiratory Epidemiology and Public Health, National Heart & Lung Institute, Imperial College London, London, United Kingdom.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Burney
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D044383:Black People / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009549:Nigeria / Q000453:epidemiology; D009749:Nutrition Surveys; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000208:ethnology* / Q000503:physiopathology*; D012016:Reference Values; D012307:Risk Factors; D012737:Sex Factors; D013147:Spirometry; D014797:Vital Capacity; D044465:White People / Q000706:statistics & numerical data; D001741:Black or African American
keywords: FVC; Nigeria; lung function; spirometry