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 analyzed 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 (1) patients with an increase of at least 300 mg of levodopa-equivalent dose (LED) and (2) patients without treatment change, matched for age, sex, and disease duration.

Results: We identified 101 matched pairs of patients with and without a treatment increase. LED increases were mostly 300 to 375 mg/day. Forty-two percent with treatment increase had ≥30% improvement in overall UPDRS motor score, a further 35% had substantial subjective improvement, but only 1 had an objective excellent (>70%) treatment response. Women responded better than men by 5.4 points (95% confidence interval [CI]: 2.7-8.1). All motor features improved with treatment, but after adjustment for age, sex, and initial score, only rest tremor (P < 0.001), rigidity (P = 0.01), bradykinesia (<0.001), posture (P = 0.01), and 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.