Table 2 Patient characteristics and non-motor symptoms of PD meta-regression analysis among cases ^a

Age at examination

-0.0229428

0.0005514

-0.0123411

0.0664692^b

0.0188255

0.0099428

Percent men

-2.136381

-0.2987655

0.3672128

1.512528

-1.614856

-0.4417779

Disease duration

-0.0117009

0.1112542^b

0.0342322

0.0841153^b

-0.0535196

-0.0164648

Symptom assessment (ref = Self-report symptom)^c

Clinical exam/diagnosis

-0.7969928^b

N/A

-0.2571586

N/A

N/A

0.4188744

Structured questionnaire

-0.6081471^b

0.4599401

0.0039112

0.0728903

N/A

0.5019682

Smell test

N/A

N/A

N/A

N/A

1.580798^b

N/A

Continent (ref = North America)

Europe

0.2150189

0.1268662

0.4494578^b

-0.152538

0.1744257

-0.0748215

Asia

-0.7000721

1.174114^b

0.9805807^b

-0.292603

-0.5923392

-0.3263885

Other

0.051124

0.6902194

0.6824674^b

0.2518004

-0.018769

-0.1487844