Psychometric evaluation of the Japanese version of the fear of pain questionnaire-III and its association with dental anxiety: a cross-sectional study

BACKGROUND: Fear of pain is a significant concern related to chronic pain and its impact on daily functioning. It is also associated with dental anxiety, highlighting its relevance in dental practice. This study aimed to validate the Japanese version of the Fear of Pain Questionnaire-III (FPQ-III) and explore its relationship with dental anxiety. METHODS: 400 participants completed the Japanese version of the FPQ-III, with 100 participants re-evaluated after one month. Convergent validity was tested against dental anxiety and pain catastrophizing, while discriminant validity was assessed by examining general anxiety and depression correlations. Confirmatory factor analysis was used to examine the factorial validity of the FPQ-III and a shortened version of the FPQ-III (FPQ-9). Item response theory was applied for each subscale to estimate the discriminative power of each item and draw a test information curve. Structural equation modeling (SEM) was used to investigate the relationship between fear of pain and dental anxiety. RESULTS: Data from 400 participants (200 women, 44.9 ± 14.5 years) were analyzed. The FPQ-III showed good internal validity, intra-examiner reliability, discriminant validity, and convergent validity. Confirmatory factor analysis results supported a three-factor structure, and the FPQ-9 showed a good fit. Test information curves demonstrated that the FPQ-9 maintained high accuracy over a similarly wide range as the FPQ-III. SEM revealed that fear of minor pain was associated with dental anxiety via fear of medical pain even in individuals without painful medical or dental experiences (indirect effect 0.48 [95% CI: 0.32–0.81]). Fear of severe pain tended to be higher in individuals with chronic pain compared to those without (latent mean values 0 vs. 0.27, p = 0.002) and was also associated with dental anxiety via fear of medical pain in women (indirect effect 0.15 [95% CI: 0.01–0.34]). CONCLUSION: The Japanese version of the FPQ-9 demonstrated high reliability and validity, making it a valuable tool in dental clinical and research settings. It provides insights into the fear of pain among individuals with chronic pain and dental anxiety, informing potential intervention strategies.