Validity and reliability of the Persian version of illness invalidation inventory (3*I) among patients with non-inflammatory rheumatic painful disorders

Abstract

Abstract Background The Invalidation Illness Inventory (3*I) is an instrument that assesses invalidation (including discounting and lack of understanding dimensions) experienced by patients with rheumatic disorders. This study aimed to translate and validate the 3*I in Iran. Methods Following translation of the 3*I into the Iranian language (Persian), a cross-sectional study was conducted. A consecutive sample of females with chronic non-inflammatory rheumatic painful diseases completed the questionnaire. Patients also completed the Revised Symptom Impact Questionnaire (SIQR) and the Short Form Health Survey-12 (SF-12). To examine convergent validity, the correlation between the 3*I, the SIQR, and the SF-12 was assessed. The reliability of the 3*I was examined by internal consistency (the Cronbach's alpha coefficient) and intraclass correlation coefficient (ICC). Results In all 196 patients participated in the study. The mean (SD) age of patients was 45.62 ± 10.70 years. Several significant correlations between the Invalidation Illness Inventory (discounting/lack of understanding) with the symptom impact (SIQR) and the short form health survey (SF-12) were observed lending support to the convergent validity of the 3*I. The Cronbach’s alpha coefficients were acceptable for most dimensions and sources, ranging from 0.52 to 0.88. Most ICC values for the dimensions of 3*I were above 0.75. Conclusions The findings indicated that the Persian version of Illness Invalidation Inventory (3*I) is a valid instrument for invalidation assessment in patients with chronic pain. Given the high frequency of perceived invalidation among patients with rheumatic painful disorders, serious attention is needed to the issue in clinical and research settings.

Keywords

• Pain
• Fibromyalgia
• Invalidation
• Chronic musculoskeletal pain
• Validation