Table 2. Baseline Demographics and Characteristics for All Patients in the Cohort.

	ICD	DDS	ICD and DDS	No ICD or DDS	Total	Significance among subgroups
Mean age of PD (symptom) onset	44.20±7.40	45.00±1.00	40.00	48.84±9.54	48.54±9.40	F(3,141) = 0.82, p = 0.49
Mean age at time of surgery	58.50±7.50	60.50±7.14	50.00	61.61±8.86	61.39±8.77	F(3,155) = 0.82, p = 0.49
Mean UPDRS-III OFF MEDICATION	45.83±19.83	43.50±9.88	32.00	42.24±12.10	42.35±12.34	F(3,143) = 0.40, p = 0.75
Mean Hoehn and Yahr Staging OFF MEDICATION	3.00	3.00	2.5	2.87	2.88±0.71	χ2(15) = 9.51
Mean UPDRS-III ON MEDICATION	28.20±10.94	20.00±6.88	20.00	23.57±9.11	23.61±9.09	F(3,133) = 0.68, p = 0.56
Mean Hoehn and Yahr Staging ON MEDICATION	2.10	2.13	2.0	2.34	2.32±0.44	χ2(12) = 3.94
Mean pre-operative levodopa equivalent dose (mg)	734.06±388.32	1270.83±743.76	2250.00	877.11±510.88	888.80±522.32	F(3,141) = 3.13, p = 0.03
Pre-operative dopamine agonist usage	4/6	0/4	1/1	81/148	86/159	χ2(6) = 6.51
Gender (M/F)	3/3	4/0	1/0	105/43	113/46	χ2(3) = 3.33

MEDICATION; all PD medications.