Impact of Using Pre- and Postbronchodilator Spirometry Reference Values in a Chinese Population.

Abstract

<b>Rationale:</b> Spirometry reference equations that are derived from a large, nationally representative general population are warranted in China, and the impact of using prebronchodilator (pre-BD) and post-BD spirometry reference values has yet to be assessed in Chinese populations. <b>Objectives:</b> To present the pre-BD and post-BD spirometry reference values for Chinese adults using the China Pulmonary Health (CPH) Study. <b>Methods:</b> A reference population of 17,969 healthy, nonsmoking participants in the CPH Study was used to calculate the pre- and post-BD reference values for FEV₁, FVC, and FEV₁/FVC ratio. Pre- and post-BD reference values were applied to the entire CPH population (<i>N</i> = 50,991) to illustrate the divergence between the use of different references in determining disease prevalence and severity grading. <b>Measurements and Main Results:</b> The prevalences of airflow limitation were 5.36% using the pre-BD reference and 8.02% using the post-BD reference. Individuals who had a post-BD FEV₁/FVC ratio lower than the post-BD reference value but higher than the pre-BD reference value were found to have significantly higher rates of self-reported respiratory symptoms and significantly lower values on spirometry indicators than those whose post-BD FEV₁/FVC ratio was greater than the post-BD reference value. An additional 3.51% of participants were identified as having grade II-IV chronic obstructive pulmonary disease using the post-BD FEV₁ predicted values. <b>Conclusions:</b> This study generated and applied pre- and post-BD spirometry reference values in a nationally representative Chinese adult population. Post-BD reference values may serve as an additional criterion in identifying individuals at risk for obstructive pulmonary diseases, and their diagnostic and prognostic values should be further investigated.