Letter in response to Picillo et al., in relation to Szewczyk-Krolikowski et al.: The influence of age and gender on motor and non-motor features of early Parkinson's disease: Initial findings from the Oxford Parkinson disease Center (OPDC) discovery cohort

Abstract

We thank Picillo et al. for their interest in our recent publication [1]. Their previous study [2] has several differences from the OPDC study and in particular was smaller (200 PD patients and 93 controls versus 490 PD patients and 176 controls). Whilst their data suggested that there were gender differences in the frequency of non-motor symptoms (NMS) between PD patients and controls, they did not include any formal statistical test for interaction, making this hard to interpret as some differences may be due to chance.