Treatment Responsiveness of Motor Features in Parkinson's Disease: A Matched Case‐Control Analysis

Background: Treatment response in PD is important clinically and for research diagnostic criteria but few objective data show treatment-responsiveness of PD motor features. Objectives: To evaluate the treatment response of motor features to moderate treatment doses in a “real-world” PD cohort. Methods: We analysed data from a community-based incident cohort of PD in North-East Scotland (PINE study). We assessed change in the UPDRS motor scale and its individual items over a period of up to 13 months comparing (i) patients with an increase of at least 300mg of levodopa-equivalent dose (LED) and (ii) patients without treatment change, matched for age, gender, and disease duration. Results: We identified 101 matched pairs of patients with and without a treatment increase. LED increases were mostly 300-375mg/day. 42% with treatment increase had ≥30% improvement in overall UPDRS motor score, a further 35% had substantial subjective improvement, but only one had an objective excellent (>70%) treatment response. Women responded better than men by 5.4 points (95% CI 2.7–8.1). All motor features improved with treatment, but after adjustment for age, gender, and initial score only rest tremor (p<0.001), rigidity (p=0.01), bradykinesia (<0.001), posture (p=0.01), gait (p=0.03) had significant improvements, compared to those with no treatment change. Dopa-less-responsive motor items, taken together, had small statistically significant relative improvements (1.1-point difference [95% CI 0.4–1.8], p=0.004). Conclusions: Motor items sometimes previously considered dopa-unresponsive have small improvements with moderate LED increases. Women respond better than men. Excellent treatment responses are uncommon. These data can inform clinical decisions about treatment.