Internet-and computer-based cognitive-behavioral treatments have been introduced as novel approaches to deliver standard, quality treatment that may reduce barriers to care. The purpose of this review is to quantitatively summarize the literature examining the treatment effects of Internet- or computer-based treatment (ICT) on anxiety. Nineteen randomized controlled ICT trials were identified and subjected to fixed and random effects meta-analytic techniques. Weighted mean effect sizes (Cohen's d) showed that ICT was superior to waitlist and placebo assignment across outcome measures (ds=.49-1.14). The effects of ICT also were equal to therapist-delivered treatment across anxiety disorders. However, conclusions were limited by small sample sizes, the rare use of placebo controls, and other methodological problems. In addition, the number of available studies limited the opportunity to conduct analyses by diagnostic group; there was preliminary support for the use of ICT for panic disorder and phobia. Large, well-designed, placebo-controlled trials are needed to confirm and extend the results of this meta-analysis.
(c) 2008 Wiley Periodicals, Inc.