In an outpatient clinic a 58-year-old smoker reports chronic cough with sputum for three winters, progressive exertional dyspnea, and wheezing relieved partly by albuterol with no acute fever or chest pain. Which evaluation best establishes a new diagnosis of chronic lung disease?

The correct evaluation establishes COPD by confirming persistent airflow limitation in stable state with clinical correlation and risk stratification, fitting a 58-year-old smoker with three winters of productive cough, progressive exertional dyspnea and partly responsive wheeze without fever or chest pain, where post-bronchodilator FEV1/FVC reduction proves fixed obstruction and symptom-exacerbation assessment guides therapy. The pre-bronchodilator-only approach fails by reversibility because baseline obstruction cannot separate fixed COPD from reversible asthma, critical with partial relief, since post-bronchodilator persistence is definitional. Post-bronchodilator spirometry during acute febrile illness fails by stability because infection and transient bronchospasm depress function and exaggerate symptoms, so chronic diagnosis must await stable baseline. Post-bronchodilator spirometry with low-dose CT without symptom assessment fails by management because CT addresses cancer risk but not dyspnea burden or exacerbation history needed for grouping and treatment. Exam caveat: symptoms, wheeze relief, hyperinflation or oximetry alone never establish COPD and normal imaging or oximetry does not exclude it; persistent post-bronchodilator obstruction in compatible context is required. Practical check: verify acceptable repeatable spirometry with proper hold when safe, record pack-years, exacerbations, CAT or mMRC, eosinophils and comorbidities, and pair diagnosis with cessation, vaccination and inhaler review.