Development and initial validation of the ILD-Anxiety-Questionnaire (IAQ): A new instrument for assessing disease specific fears in interstitial lung disease.

Introduction: Multiple studies focusing on chronic lung diseases (i.e. COPD), have indicated that the quality of life (QoL) can be impacted by disease-related fears. In the context of Interstitial Lung Diseases (ILD), however, these have never been systematically examined. Therefore, the aim of the present study was to develop and evaluate an appropriate measuring tool, and to investigate the influence of disease-related anxieties on QoL in ILD.

Method: N = 166 ILD patients participated in the study and completed an itempool on disease-related fears, based on the COPD-Anxiety-Questionnaire (CAF-R) and expert assessments. Further, demographic and psychological variables were assessed (anxiety: GAD-7, QoL: K-BILD; Beliefs about Health: KKG). Psychometric properties were analyzed (factor structure, reliability, validity). Regression analyses were used to calculate the differential predictive power of disease-related anxieties on QoL.

Results: The factor structure was confirmed (Scales: Fear-of-Dependence-and-Progression, Fear-of-Social-Exclusion-and-Isolation, Fear-of-Physical-Activity, Fear-of-Dyspnea, and Sleep-related- Complaints). The Scales showed satisfying reliabilities (α = 0.68 to 0.89) and good validity. Disease-related anxieties proved to be differential predictors for different scales of the K-BILD (ß = -0.15 to ß = -0.58, all ps < .01).

Conclusions: The ILD-Anxiety-Questionnaire (IAQ) is an easy-to-use, valid measurement tool for assessing disease-related anxieties. These vary in their impact on different aspects of QoL. Therefore, it might aid in specifying the indication for potential psychological supplementary interventions. Additional long-term studies are required to investigate how specific anxieties affect both overall and condition-specific QoL in diverse situations.