This study sought to validate empirically, through factor analysis, the theoretically developed Illness Perceptions Questionnaire (IPQ) measure of illness representations, and investigated how illness representations varied within an illness condition between different treatments.Methods.
Two hundred and fourteen coronary artery disease (CAD) patients, 70 of whom were undergoing medication, 71 to undergo angioplasty and 73 to undergo coronary artery bypass surgery (CABG), completed the New Zealand Heart Attack Recovery Project version of the IPQ. The core cognitive illness representation statement responses were subject to principal components analyses (PCA), with oblique rotation. Identity data were examined regarding symptom frequency. Subscales based on factor structures and frequency scores were utilized to investigate treatment group differences in illness beliefs through analysis of covariance (ANCOVA).Findings.
PCA of the core components indicated four factors labelled: ‘illness impact’, ‘duration’, ‘control’, and ‘self-image’, accounting for 46.5% of the variance. The most frequently experienced symptoms were fatigue, breathlessness and chest-pain (angina). ANCOVAs showed significant treatment group differences in frequency of chest-pain experienced (medication < CABG, p <.01) and differences on illness ‘duration’ beliefs (medication > revascularization groups, p <.001).Discussion.
The results produced a modified structure for the IPQ, which appeared to reflect the nature of the illness under study and the possible fractionation of the core illness representation components. Responses on the subscales created were also related to the position within the ‘subjective experience with the illness’ that a patient had reached and the treatment being undertaken.