SERPINA1 and pulmonary emphysema: Patients with AATD (based on the serum AAT levels ≤100 mg/dL) were younger than individuals with normal AAT levels (61.7 years vs 66 years, p<0.001), with a lower pack-year index (39 versus 45, p<0.001), were more likely to have characteristics of emphysema (34.3% versus 18.9%, p = 0.003), have less dyspnea and were less likely to have a Charlson index≥3 (23.7% vs 39.7%,p<0.001).