Adaptation and validation of the chronic illness-related shame scale among patients with knee osteoarthritis in Singapore

BACKGROUND: Osteoarthritis (OA) of the knee is one of the most common and disabling conditions worldwide. A neglected aspect of knee OA is its psychosocial impact, such as shame. However, assessment tools to measure shame among patients diagnosed with knee OA are lacking. In this study, the psychometric properties of the Chronic Illness-related Shame Scale (CISS) were evaluated among knee OA patients in Singapore. METHODS: Adaptations were made to CISS for use among the knee OA population. An exploratory factor analysis (EFA) was performed to analyze the factor structure. Cronbach’s Alpha and corrected item-total correlations were used to evaluate the internal consistency. Spearman correlation coefficient was used to test the correlation between CISS and Patient Health Questionnaire-4 (PHQ-4) to determine the validity of the instrument. RESULTS: The EFA yielded a one-factor structure, with an eigenvalue of 4.78 explaining 68.25% of variance. Cronbach Alpha was 0.92, which indicated good internal consistency. The Spearman correlation revealed a significant correlation between CISS and PHQ-4. CONCLUSIONS: The adapted CISS is a valid and reliable instrument to measure shame for knee OA patients. Both research and clinical settings can benefit from the use of the adapted CISS for assessing shame among knee OA patients.