An urgent need for African spirometry reference equations: the Paediatric and Adult African Spirometry study

BACKGROUND: The GLI₂₀₁₂ (Global Lung Initiative 2012) has provided the largest data set to date for multi-ethnic spirometry reference equations; however, data on African populations are limited. In pulmonary function testing, diagnosis of lung disorder is based on comparing the individual's lung function to a reference appropriate for sex and ethnicity.METHODS: We conducted a systematic review of studies reporting spirometry results in healthy children and adults in Africa. Data from these studies were collated for Z-scores of forced expiratory volume in 1 sec (zFEV₁), forced vital capacity (zFVC) and zFEV₁/FVC compared to GLI reference equations.RESULTS: Nine studies, covering a total of 4750 individuals from North, South, East, West and Central Africa (52% were female), were reviewed. Marked differences were noted between individuals from North Africa and sub-Saharan Africa. The Southern zFEV₁ (-0.12 ± 0.98), zFVC (-0.15 ± 0.98) and zFEV₁/FVC (0.05 ± 0.89), Central zFEV₁ (-0.16 ± 0.79), zFVC (-0.09 ± 0.83) and zFEV₁/FVC (-0.17 ± 0.71) and East African zFEV₁ (0.10 ± 0.88), zFVC (0.16 ± 0.85) and zFEV₁/FVC (-0.10 ± 0.95) cohorts had an excellent fit with the GLI-African American. The West African showed a poor fit to all reference equations. The North African group showed the best fit for the GLI Caucasian zFEV₁ (-0.12 ± 1.37), zFVC (-0.26 ± 1.36) and zFEV₁/FVC (0.25 ± 1.11). The zFEV₁/FVC ratios were stable across all the populations.CONCLUSION: Current evidence seems to support the use of GLI₂₀₁₂ reference values in North African and sub-Saharan African populations after taking into account ethnic correction factors.