The efficacy and safety of nebulized glycopyrrolate inhalation solution (GLY), administered twice daily (BID) via the innovative eFlow® Closed System nebulizer (PARI Pharma GmbH, Starnberg, Germany), were demonstrated in two replicate, placebo-controlled, 12-week Phase III studies (GOLDEN 3 and GOLDEN 4). This report evaluates the efficacy and safety of GLY by baseline disease severity and age in the pooled GOLDEN 3 and GOLDEN 4 patient population (N=1,294).Patients were grouped by baseline predicted post-bronchodilator FEV1 (<50%, ≥50%) and age (<65, ≥65, ≥75 years).GLY (25 and 50 μg BID) produced significant improvements in trough FEV1 in FEV1% predicted <50% (0.070 L, 0.079 L) and ≥50% (0.112 L, 0.126 L) subgroups (P<0.01 vs placebo), and in patients aged <65 (0.056 L, 0.086 L), ≥65 (0.140 L, 0.124 L), and ≥75 (0.144 L, 0.120 L) years (P<0.05 vs placebo). St George's Respiratory Questionnaire (SGRQ) total score was significantly improved with GLY 25 and 50 μg BID (P<0.05 vs placebo) in FEV1% predicted <50% (-3.237, -3.061) and ≥50% (-3.392, -2.322) and in <65 years (-3.447, -2.318) and ≥65 years (-3.053, -3.098) subgroups. In patients aged ≥75 years, GLY 25 μg reduced SGRQ total score by -6.278 units (P<0.01 vs placebo). The incidence of treatment-emergent adverse events was similar between GLY and placebo across all subgroups, and the overall incidence of cardiovascular events was low.Nebulized GLY improved lung function and health status and was well tolerated over 12 weeks in patients with moderate-to-very-severe COPD, irrespective of baseline disease severity and age.NCT02347761, NCT02347774.