A longitudinal analysis of electronic cigarette forum participation.

Electronic cigarette (e-cigarette) Internet forums are social networking websites that allow members around the world to share information and personal experiences about e-cigarettes. However, little is known about their popularity and reach. This longitudinal study investigated indicators of participation (membership, number of discussion boards, and number of message posts) in 77 e-cigarette forums from February 2016 to January 2017.