Do neurologists make a difference in Parkinson disease care?

Willis et al.1 reviewed Medicare data to explore 2 questions. First, what characteristics determine whether a patient with Parkinson disease (PD) sees a neurologist? Second, are patients who see a neurologist likely to live longer than patients who do not see a neurologist? The Medicare data for this study data came from insurance claims. When a doctor sees a patient, he or she provides some basic information on forms sent to Medicare as reasons for payment, such as the diagnosis being treated. This type of data is powerful due to the large number of patients with these data. However, insurance claim-based data sources lack detailed information, so reaching definite conclusions is difficult. For example, an insurance claim just records that a patient has a diagnosis of PD, but does not record …