Table 1

Demographic and clinical characteristics at baseline for the patients in the two studies

VariableTracking Parkinson’s cohort (n=1601) mean (SD) or n (%)Discovery cohort (n=944) mean (SD) or n (%)P-value difference between cohorts
Female554 (34.6%)334 (35.4%)0.69*
Ethnicity (non-white)28 (1.8%)20 (2.1%)0.51*
Age diagnosis (years)65.9 (9.3)65.9 (9.6)0.92†
Disease duration from diagnosis (years)1.3 (0.9)1.2 (0.9)0.03†
MDS-UPDRS part I‡9.1 (5.2)8.8 (5.1)0.09†
MDS-UPDRS part II‡9.5 (6.2)8.7 (6.0)<0.001†
MDS-UPDRS part III‡22.3 (11.9)26.4 (10.8)<0.001†
MDS-UPDRS part IV‡0.7 (1.7)0.3 (1.1)<0.001†
MDS-UPDRS total (all four parts)‡41.8 (18.7)44.2 (17.5)0.002†
MoCA (adjusted for education years)‡25.4 (3.4)25.0 (3.3)0.012†
Untreated149 (9.3%)119 (12.6%)0.01*
LEDD (mg)293 (205)282 (212)0.20†
LEDD (those on medication) (mg)324 (190)327 (194)0.77†
Hoehn and Yahr§ median (IQR)1 (1–2)2 (2–2)<0.001*
  • Motor assessments (UPDRS and Hoehn and Yahr) were rated in the clinically defined ‘on medication’ state for treated patients with PD.

  • 2 test.

  • †T-test.

  • ‡Changed denominator where 80% or more of questions were answered.

  • §In Tracking Parkinson’s cohort, Hoehn and Yahr 1.5 and 2.5 were changed to 1 and 2, respectively, for comparison with Oxford Parkinson’s Disease Centre Discovery cohort.

  • LEDD, levodopa equivalent daily dose; MDS, Movement Disorders Society; MoCA, Montreal Cognitive Assessment; UPDRS, Unified Parkinson’s Disease Rating Scale.