Figure 1

Patient selection diagram. Patients were selected by a modified stratified systematic sampling: every other patient in the first quintile with the greatest COPD-related healthcare costs and every fourth patient in the remaining quintiles. If a patient received primary or pulmonary care from non-VA providers, airflow limitation (FEV₁/FVC < 0.7) was not present on spirometry, or if they were in hospice care, they were excluded and replaced by the next patient on the rank list.