To the Editor Qin et al1 have performed a meta-analysis of the observational association of circulating cytokines with Parkinson disease (PD) status, finding elevated levels of interleukin 6 and other cytokines among patients with PD compared with healthy control participants. Meta-analyses of observational outcomes, however, are prone to biases because of unresolvable confounding, requiring cautious interpretation.2
Nilsonne G, Lekander M. Circulating Interleukin 6 in Parkinson Disease. JAMA Neurol. 2017;74(5):607–608. doi:10.1001/jamaneurol.2017.0037
Coronavirus Resource Center
Customize your JAMA Network experience by selecting one or more topics from the list below.