Validation of the global lung initiative 2012 multi-ethnic spirometric reference equations in healthy urban Zimbabwean 7–13 year-old school children: a cross-sectional observational study

Abstract

Background: The 2012 Global Lung Function Initiative (GLI 2012) provide multi-ethnic spirometric reference equations (SRE) for the 3-95 year-old age range, but Sub-Saharan African populations are not represented. This study aimed to evaluate the fit of the African-American GLI 2012 SRE to a population of healthy urban and peri-urban Zimbabwean school-going children (7-13 years). Methods: Spirometry and anthropometry were performed on black-Zimbabwean children recruited from three primary schools in urban and peri-urban Harare, with informed consent and assent. Individuals with a history or current symptoms of respiratory disease or with a body mass index-z score (BMI) < − 2 were excluded. Spirometry z-scores were generated from African-American GLI 2012 SRE, which adjust for age, sex, ethnicity and height, after considering all GLI 2012 modules. Anthropometry z-scores were generated using the British (1990) reference equations which adjust for age and sex. The African-American GLI 2012 z-score distribution for the four spirometry measurements (FVC, FEV 1 , FEV 1 / FVC and MMEF) were evaluated across age, height, BMI and school (as a proxy for socioeconomic status) to assess for bias. Comparisons between the African-American GLI 2012 SRE and Polgar equations (currently adopted in Zimbabwe) on the percent-predicted derived values were also performed. Results: The validation dataset contained acceptable spirometry data from 712 children (344 girls, mean age: 10.5 years (SD 1.81)). The spirometry z-scores were reasonably normally distributed, with all means lower than zero but within the range of ±0.5, indicating a good fit to the African-American GLI 2012 SRE. The African-American GLI 2012 SRE produced z-scores closest to a normal distribution. Z-scores of girls deviated more than boys. Weak correlations (Pearson's correlation coefficient < 0.2) were observed between spirometry and anthropometry z-scores, and scatterplots demonstrated no systematic bias associated with age, height, BMI or socioeconomic status. The African-American GLI 2012 SRE provided a better fit for Zimbabwean paediatric spirometry data than Polgar equations. Conclusion: The use of African-American GLI 2012 SRE in this population could help in the interpretation of pulmonary function tests.

Prevalence and antimicrobial resistance profiles of respiratory microbial flora in African children with HIV-associated chronic lung disease

“…The lung function z-score were calculated using global lung function initiative GLI/ERS reference equations and the African American module [19]. Our team validated this among children in Zimbabwe and findings are published elsewhere [20]. Comparison of categorical data including semi-quantitative bacterial load distribution was performed by Fisher's exact test or Chi-square test where appropriate.…”

Spirometry Abnormalities and Its Associated Factors Among Primary School Children in a Nigerian City

“…There is some evidence that GLI reference equations for African Americans could be applied to African children, as GLI references would ideally be validated in local populations as much as possible, especially in Africa. 26 , 35 , 36 In a study on adult Nigerians by Obaseki et al, 26 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 for African Americans. In a study in Malawi, Meghji et al 27 reported the prevalence of spirometric restriction to be 38.6% using National Health and Nutrition Examination Survey III reference ranges and 9.0% using local reference ranges.…”

The applicability of the global lung initiative equations and other regional equations on a sample of healthy Middle Eastern adolescents

“…The following conditions should be met to determine that the reference equation is suitable for the study sample: (1) Normal distribution of. First, the produced spirometry z‐scores should be normally distributed, 25 (2). Second, the z ‐scores’ mean and standard deviations (SD) should ideally be 0 and 1, respectively; 26 however, means up to ±0.5 are tolerated 15 …”