Background This interim 12‐month analysis is a part of an open‐label, observational, prospective study on health outcomes and cost impact of levodopa/carbidopa intestinal gel (LCIG, Duodopa) in Parkinson disease (PD). The specific aim was to investigate clinical and health‐related quality of life (HRQoL) effects in routine care. Methods Unified PD rating scale (UPDRS) was the primary efficacy measurement. PD QoL questionnaire 39 (PDQ‐39) assessed HRQoL. Subjects were assessed at baseline, ≥3 months after surgery, and then every 3 months. Results Twenty‐seven treatment‐naïve subjects when started with LCIG showed a decrease in UPDRS score that was statistically significant throughout the year: UPDRS total score (mean ± SD), baseline = 52.1 ± 16.1, N = 27, month 0 (first visit; at least 3 months after permanent LCIG) = 43.1 ± 16.7, N = 27, P = 0.003; month 12 = 42.5 ± 22.6, n = 25, P = 0.017. PDQ‐39 results also showed a tendency for improvement: PDQ‐39 (mean ± SD), baseline = 33.6 ± 10.8, N = 27, month 0 = 27.1 ± 11.8, N = 27, P = 0.001; 12 months = 28.8 ± 12.8, n = 23, P = 0.126. Conclusions LCIG provides functional improvement beginning at first visit that is sustained for 12 months.