Development and initial testing of the self-care of chronic illness inventory

AIM: The aim was to develop and psychometrically test the self-care of chronic illness Inventory, a generic measure of self-care.

BACKGROUND: Existing measures of self-care are disease-specific or behaviour-specific; no generic measure of self-care exists.

DESIGN: Cross-sectional survey.

METHODS: We developed a 20-item self-report instrument based on the Middle Range Theory of Self-Care of Chronic Illness, with three separate scales measuring Self-Care Maintenance, Self-Care Monitoring, and Self-Care Management. Each of the three scales is scored separately and standardized 0-100 with higher scores indicating better self-care. After demonstrating content validity, psychometric testing was conducted in a convenience sample of 407 adults (enrolled from inpatient and outpatient settings at five sites in the United States and ResearchMatch.org). Dimensionality testing with confirmatory factor analysis preceded reliability testing.

RESULTS: The Self-Care Maintenance scale (eight items, two dimensions: illness-related and health-promoting behaviour) fit well when tested with a two-factor confirmatory model. The Self-Care Monitoring scale (five items, single factor) fitted well. The Self-Care Management scale (seven items, two factors: autonomous and consulting behaviour), when tested with a two-factor confirmatory model, fitted adequately. A simultaneous confirmatory factor analysis on the combined set of items supported the more general model.

CONCLUSION: The self-care of chronic illness inventory is adequate in reliability and validity. We suggest further testing in diverse populations of patients with chronic illnesses.