Background: Patients increasingly use the internet to access health information. Inadequate health literacy is common and frequently limits patient comprehension of healthcare literature. We aimed to assess the readability of online consumer-orientated Parkinson's disease (PD) information using two validated measures.
Method: We identified the 100 highest ranked consumer-orientated PD webpages and determined webpage readability using the Flesch-Kincaid and Simple Measure Of Gobbledygook (SMOG) formulae.
Results: None of the webpages analysed complied with current readability guidelines. Commercial websites were significantly easier to read (p = 0.035). The Flesch-Kincaid formula significantly underestimated reading difficulty (p < 0.0001). Ease of reading correlated weakly with search engine ranking (r = 0.35, p = 0.0004).
Conclusions: Only 1% of the top 100 PD information webpages are fully comprehensible to the average adult. Simple Measure Of Gobbledygook should be the preferred measure of webpage readability. Parkinson's disease information websites require major text revision to comply with readability guidelines and to be comprehensible to the average patient.