Prediction of outcome in the treatment of specific phobia. A cross validation study.

The purpose of this study was to investigate possible predictors of treatment outcome in specific phobia at 1 week after treatment, and at I year follow-up. The subjects (n = 138) came from four studies (two on spider phobia, one on blood phobia and one on injection phobia), and all had been diagnosed with simple phobia according to DSM-III-R. The dependent variable was clinically significant improvement in three different factors; avoidance behavior in a behavior test, self-rated anxiety during the test, assessor rating of phobic severity or fainting behavior. Fourteen variables covering self-report, demographic and physiological variables, and data from the behavior test were used as prognostic variables. Multiple regression analyses were used in a cross validation procedure. The results showed that diastolic blood pressure at pretest was a predictor at post-treatment for one sample and credibility was found as a predictor for the other sample both at post-treatment and at 1 year follow-up. Analyses were made for the diagnoses and the treatments but the results were inconclusive. Despite the large sample size and the cross validation procedure no stable predictors were found for short- and long-term outcome. The few significant predictors should be considered as chance findings.