Psychometric Testing of the Self-Care of Coronary Heart Disease Inventory (SC-CHDI).

Although coronary heart disease (CHD) requires a significant amount of self-care, there are no instruments available to measure self-care in this population. The purpose of this study was to test the psychometric properties of the Self-Care of Coronary Heart Disease Inventory (SC-CHDI). Using the Self-Care of Chronic Illness theory, we developed a 22-item measure of maintenance, management, and confidence appropriate for persons with stable CHD and tested it in a convenience sample of 392 adults (62% male, mean age 61.4 ± 9.6 years). Factorial validity was tested with confirmatory factor analysis. Convergent validity was tested with the Medical Outcomes Study MOS-SAS Specific Adherence Scale and the Decision Making Competency Inventory (DMCI). Cronbach alpha and factor determinacy scores (FDS) were calculated to assess reliability. Two multidimensional self-care scales were confirmed: self-care maintenance included "consultative behaviors" (e.g., taking medicines as prescribed) and "autonomous behaviors" (e.g., exercising 30 minute/day; FDS = .87). The multidimensional self-care management scale included "early recognition and response" (e.g., recognizing symptoms) and "delayed response" (e.g., taking an aspirin; FDS = .76). A unidimensional confidence factor captured confidence in each self-care process (α = .84). All the self-care dimensions were associated with treatment adherence as measured by the MOS-SAS. Only self-care maintenance and confidence were associated with decision-making (DCMI). These findings support the conceptual basis of self-care in patients with CHD as a process of maintenance that includes both consultative and autonomous behaviors, and management with symptom awareness and response. The SC-CHDI confidence scale is promising as a measure of self-efficacy, an important factor influencing self-care.