Prognostic impact of pre- and post-bronchodilator airflow obstruction and post-bronchodilator reference values in a population-based study. On behalf of the PLATINO group

INTRODUCTION: Post-bronchodilator (BD) spirometry testing is required for a diagnosis of airflow obstruction (AO) and COPD. We compared the impact of pre- and post-BD AO, as well as that of pre-BD and post-BD reference values, on survival, exacerbations, and FEV₁ decline. METHODS: We analyzed data derived from the Proyecto Latinoamericano de Investigación en Obstrucción Pulmonar (PLATINO, Latin American Project for the Investigation of Obstructive Lung Disease) study, involving individuals residing in three Latin American cities and evaluated 5-9 years after baseline examination. Categories were formed by pre-and post-BD FEV₁/FVC < the 5th percentile (lower limit of normal) by PLATINO reference values (pre-BD and post-BD). RESULTS: At baseline, 2,942 participants completed pre- and post-BD spirometry; 2,262 were normal (controls); 139 had pre-BD AO (FEV₁/FVC below the lower limit of normal; reversible AO); 230 had pre-BD and post-BD AO (persistent AO); 43 had only post-BD AO; and 148 had a preserved ratio impaired spirometry (PRISm) pattern. Additionally, 105 individuals had post-BD AO by post-BD reference values. When compared with controls, the reversible AO group (hazard ratio [HR] = 1.9; 95% CI, 1.1-3.1), the persistent AO group (HR = 2.99; 95% CI, 2.1-4.3), the PRISm group (HR = 1.6; 95% CI, 0.9-2.7), and the group of patients with AO by post-BD reference values (HR = 1.9; 95% CI, 1.1-3.4) had a higher mortality; those with a PRISm pattern and those with persistent AO had more exacerbations, and the latter group had an additional FEV₁ decline in adjusted models (-13.4 mL/year; 95% CI, -6 to -21). The reversible AO group had a higher risk of developing COPD (post-BD AO) during follow-up (OR = 4.1; 95% CI, 2.0-8.5). CONCLUSIONS: Individuals with post-BD AO identified only with post-BD reference values had an increased risk of death. Those with pre-BD AO had higher mortality and an increased risk of developing COPD, therefore requiring close follow-up monitoring and being classified as pre-COPD patients.