Validity of the Fear of Progression Questionnaire-Short Form in Patients With Systemic Sclerosis

Objective. To validate the Dutch translation of the Fear of Progression Questionnaire-Short Form (FoP-Q-SF) for patients with systemic sclerosis (SSc). Although concerns about the future are often expressed by patients with SSc, there is no valid quantitative measure available to assess the extent to which patients with SSc are troubled by those concerns. Methods. Measurement properties of the FoP-Q-SF were assessed using a cross-sectional design that included 215 patients with SSc. Patients completed the FoP-Q-SF as well as questionnaires on physical and psychological functioning. Psychometric properties of the FoP-Q-SF were assessed using the Consensus-Based Standards for the Selection of Health Status Measurement Instruments checklist. Results. The mean +/- SD FoP-Q-SF score in patients with SSc was 30.05 +/- 8.97. There were no indications of floor or ceiling effects. Confirmatory factor analysis supported the single-factor structure of the questionnaire (chi(2)[52] = 96.84, P < 0.001, root mean square error of approximation = 0.064, chi-square/df ratio = 1.86). Cronbach's alpha was 0.86 for the questionnaire. Most of our a priori hypotheses (11 of 12) were confirmed, supporting the construct validity of the questionnaire. Conclusion. A valid measure is now available to assess fear of disease progression in patients with SSc, which is significant since fear of progression is one of the most important stressors in this patient population.