Severe health anxiety can be effectively treated with exposure-based Internet-delivered cognitive
behavior therapy (ICBT), but information about which factors that predict outcome is scarce. Using data
from a recently conducted RCT comparing ICBT (n ¼ 79) with Internet-delivered behavioral stress
management (IBSM) (n ¼ 79) the presented study investigated predictors of treatment outcome. Analyses
were conducted using a two-step linear regression approach and the dependent variable was
operationalized both as end state health anxiety at post-treatment and as baseline-to post-treatment
improvement. A hypothesis driven approach was used where predictors expected to influence outcome
were based on a previous predictor study by our research group. As hypothesized, the results showed
that baseline health anxiety and treatment adherence predicted both end state health anxiety and
improvement. In addition, anxiety sensitivity, treatment credibility, and working alliance were signifi-
cant predictors of health anxiety improvement. Demographic variables, i.e. age, gender, marital status,
computer skills, educational level, and having children, had no significant predictive value. We conclude
that it is possible to predict a substantial proportion of the outcome variance in ICBT and IBSM for severe
health anxiety. The findings of the present study can be of high clinical value as they provide information
about factors of importance for outcome in the treatment of severe health anxiety