Simultaneous Nonmotor Symptoms Do Not Affect General Validity but Interpretation of the Parkinson's Disease Motor...

Motor fluctuations are routinely documented using the Parkinson's disease (PD) home diary. However, the validity of this diary when compared to clinical observers is limited.

This study disassembled the effects of nonmotor symptoms (NMS) on inter-method agreement between the PD home motor diary and clinical observers (outside validity criterion).

A prospective observational VALIDATE-PD cohort study in advanced PD assessing symptom severity by simultaneous hourly ratings using the home diary (Off, On, dyskinetic state) and a nonmotor diary (11 key NMSs) was performed. Test validity measures (accuracy and Cohen's κ) were compared between hours with and without co-occurring NMS.

Four hundred eighty-seven hourly time periods from 47 participants were analyzed. Inter-method agreement (accuracy, Cohen's κ) of the motor diary was independent of co-occurring NMSs, but simultaneous NMSs inversely influence false ratings of motor Off and On states.

Simultaneously occurring NMSs do not affect general validity but the interpretation of the PD home motor diary.