A systematic review of the quality and fit of local spirometry studies to the Global Lung Initiative (GLI) and global chronic respiratory disease burden

Abstract

Early diagnosis and treatment are vital to combatting the global rise in chronic respiratory diseases (CRD). Spirometry can reliably support a CRD diagnosis when reference equations (RE) represent the target population. Multi-ethnic representation in Global Lung Initiative (GLI) RE has been a significant advance. However, the GLI lacks data from many global population groups, thus its diagnostic sensitivity may be reduced in local or ethnically diverse populations. We aimed to analyse global trends in PFT studies comparing the applicability (fit) of GLI RE to local populations and their geospatial relationships with CRD burden. A systematic search was conducted using PubMed® and Medline. In the resulting 46 studies, the fit of each local population’s normative PFT data (relative to GLI) was determined using standardized criterion (mean Z-score=0 & <0.5, SD=1, 90% Z-scores >-1.64 & <+1.64) and article quality was evaluated using a modified GRADE criterion. Geospatial relationships were modelled in R statistics. Only 56% of reviewed studies met the applicability criterion and 60% rated low or very low in quality. Evidence of acculturation (post migration) was found in 18% and evidence of longitudinal changes in 31% of studies. A geospatial mismatch was found between CRD burden and the normative data used to construct the GLI RE. We demonstrate a compelling need for normative spirometry data targeted to populations which are both underrepresented in the GLI and have the highest CRD burden. Improved quality in future studies could be facilitated with the adoption of a standardised protocol for normative PFT data collection and analysis.