Table 4.

Parkinson’s disease (PD) clinical stage based on the neurologist’s clinical judgment (gold standard)

Clinical stage	Clinical characteristics
Initiala	Very mild clinical manifestations; absence of disability; and no need of pharmacologic treatment or only initial therapy at low effective doses
Milda	Mild clinical and functional manifestations; minimal or no complications; and satisfactory response to conventional pharmacologic therapy
Moderatea	Moderate clinical manifestations and disability; good response; some complications are present, although not satisfactory to the conventional pharmacologic therapy
Advancedb	Severe clinical manifestations and disability; severe motor and non-motor complications; partial poor response to conventional pharmacologic therapy
Late-stageb	Very severe clinical manifestations and disability; very severe motor and non-motor complications; no response to conventional pharmacologic therapy

^aNon-advanced PD

^bAdvanced PD