Factor Structure and Psychometric Properties of the Injection Phobia Scale-Anxiety

The present investigation examined the factor structure and psychometric properties of the Injection Phobia Scale-Anxiety (IPS-Anx). Principal components analysis of IPS-Anx items in Study 1 (n = 498) revealed a 2-factor structure consisting of Distal Fear and Contact Fear. However, CFA results in Study 2 (n = 567) suggest that a 1-factor structure may be more parsimonious. IPS-Anx scores demonstrated excellent reliability including test-retest over a 12-week period in Study 3 (n = 195). Supportive evidence for convergent and divergent validity of IPS-Anx scores was also found in Study 4 (n = 319), with strong associations with disgust propensity and sensitivity and weak associations with positive affect. Further evidence of validity was found in Study 5 (n = 1,674) because IPS-Anx scores discriminated those who have experienced fainting symptoms or avoided medical procedures from those without a history of such symptoms. In Study 6, data from Studies 2 through 5 were pooled, and the findings of Study 2 were replicated. The 1-factor model also fit the data well for men and women in Study 6. Lastly, IPS-Anx scores differentiated those with blood-injection-injury phobia (n = 39) from those without this phobia (n = 43) in Study 7. These findings suggest that the IPS-Anx has excellent psychometric properties, making it suitable for use in programmatic research on injection phobia. However, future research examining the validity of a short form of the scale with only the Contact Fear items may further improve the efficiency and utility of the IPS-Anx.