Large-scale international validation of the ADO index in subjects with COPD: an individual subject data analysis of 10 cohorts

Abstract

Background Little evidence on the validity of simple and widely applicable tools to predict mortality in patients with chronic obstructive pulmonary disease (COPD) exists. Objective To conduct a large international study to validate the ADO index that uses age, dyspnoea and FEV₁ to predict 3-year mortality and to update it in order to make prediction of mortality in COPD patients as generalisable as possible. Design Individual subject data analysis of 10 European and American cohorts (n=13 914). Setting Population-based, primary, secondary and tertiary care. Patients COPD GOLD stages I–IV. Measurements We validated the original ADO index. We then obtained an updated ADO index in half of our cohorts to improve its predictive accuracy, which in turn was validated comprehensively in the remaining cohorts using discrimination, calibration and decision curve analysis and a number of sensitivity analyses. Results 1350 (9.7%) of all subjects with COPD (60% male, mean age 61 years, mean FEV₁ 66% predicted) had died at 3 years. The original ADO index showed high discrimination but poor calibration (p1 alone. Interpretation The updated 15-point ADO index accurately predicts 3-year mortality across the COPD severity spectrum and can be used to inform patients about their prognosis, clinical trial study design or benefit harm assessment of medical interventions.