Influence of vocabulary and sentence complexity and passive voice on the readability of consumer-oriented mental health information on the Internet.

Searching for health care information is one of the most common uses of the Internet by the elderly. Our earlier research showed that health care information websites may present information at levels of readability that are excessively difficult for many potential users. This study investigated the influence of several aspects of readability (vocabulary and sentence complexity and use of passive voice construction) on overall readability at several different levels of readability. Results show that easier to read sites could be differentiated most consistently from more difficult sites by vocabulary complexity. Comparison of the easiest and most difficult sites in several cases showed that sentence complexity and passive voice may also be important. These results can provide guidance for those interested in improving the readability of web sites that provide mental health information for consumers.