Validity and Reliability of Caregiver Contribution to Self-Care of Chronic Obstructive Pulmonary Disease Inventory and Caregiver Self-Efficacy in Contributing to Self-Care Scale

The study tested the construct validity and reliability of the Caregiver Contribution to Self-Care of Chronic Obstructive Pulmonary Disease (COPD) Inventory and the Caregiver Self-Efficacy in Contributing to Self-Care of COPD Scale. The two instruments were developed by modifying the Self-Care of COPD Inventory and Self-Care Self-Efficacy Scale in COPD into caregiver versions. The psychometric properties were tested in a convenience sample of 261 informal caregivers of COPD patients recruited in Italy in two cross-sectional studies. Structural validity was tested by confirmatory factor analysis, construct validity by posing several hypotheses, and internal consistency through factor score determinacy and global reliability index for multidimensional scales. In confirmatory factor analysis, the caregiver contribution to self-care maintenance, monitoring and management scales, composing the Caregiver Contribution to Self-Care of COPD Inventory, presented good fit indices. Global reliability indices ranged 0.75-0.88. The caregiver self-efficacy scale presented a comparative fit index of 0.96 and a global reliability index of 0.82. The caregiver contribution to self-care and the caregiver self-efficacy scales correlated moderately among themselves and with the patient versions of the scales, and scores were higher with caregiver-oriented dyadic care types and female caregivers. Our study provides evidence of the two instruments' construct validity and internal consistency.