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Introduction The Global Lung Function Initiative (GLI) 2022 reference values are a race neutral approach to spirometry interpretation. We aimed to determine the impact of switching from GLI 2012 to GLI 2022 on spirometry results in patients seen at Great Ormond Street Hospital for Children (GOSH).Methods A retrospective analysis of spirometry performed between 2020 and 2023. Results were interpreted and compared using both GLI 2012 and GLI 2022 to ARTP standards (LLN <-1.64z-score). Mean results between methods, and normal/abnormal classification were compared for white children and black children.Results Spirometry results were analysed in 3,254 patients aged (mean [SD]) 11.5[3.8] years. 54.5% were male. Patients/carers self-reported race using the GLI 2012 groups and at time of test as White (2,219, 68.2%), Black (512, 15.7%) and Other (523, 16.1%).When using GLI 2012, there were 1,183 (36.4%) results < LLN, compared to GLI 2022 with 1,117 (34.3%).Black children had lower spirometry z-scores with GLI 2022 than with GLI 2012 (FEV1: -1.54 vs -0.83, difference -0.71, p<0.01; FVC: -1.39 vs -0.65, difference -0.75, p<0.01).61 (11.9%) Black subjects whose results were classified as normal by GLI 2012 were reclassified as restrictive by GLI 2022. There was no change in the number of tests classified as obstructive.White children had higher spirometry z-scores with GLI 2022 than with GLI 2012 (FEV1: -0.68 vs -1.1, difference 0.40, p>0.01; FVC: -0.47 vs -0.90, difference 0.437, p<0.01. 118 (5.3%) White subjects whose results were classified as restrictive by GLI 2012 were reclassified as normal by GLI 2022. There was virtually no change in the number of tests classified as obstructive.Conclusion Interpretation of spirometry changes when switching from GLI 2012 to GLI 2022.