Objective: The Revised-Illness Perception Questionnaire (IPQ-R) assesses illness perceptions according to Leventhal's self-regulatory model. The aim of this paper is to present findings on the reliability and validity of the IPQ-R in a population of Greek cancer patients.
Methods: A total of 206 patients completed a Greek translation of the IPQ-R and the Greek version of the Beck Depression Inventory (BDI). The scale's reliability was investigated by examining its internal consistency (Cronbach's alpha) and its test-retest reliability. Structural validity was examined through factor analyses. Predictive validity was tested by regressing BDI scores on IPQ subscale scores. Inter-relationships between IPQ-R dimensions were also examined by computing Pearson's Correlation Coefficients.
Results: Cronbach's alpha showed satisfactory internal consistency for the IPQ-R subscales. Paired samples' t-test showed good test-retest reliability. Factor analysis of the IPQ-R items revealed that the Greek version reflects the structure of the original with the only difference being that the 'Consequences' and 'Emotional Representations' subscales loaded on one factor. Factor analysis of the causal dimension items revealed a different structure of Causal Representations than that of the original questionnaire yielding three main factors: Psychological Attributions, Behavioral, and External Factors. Multiple regression analyses showed that Consequences, Emotional Representations, Illness Identity, and Psychological Attributions were the best predictors for depression.
Conclusions: Translation of the IPQ-R has good reliability and similar structure to that of the original. Difficulties to confirm the structure of Causal Representations may represent cultural differences in understanding illness causation.
(c) 2009 John Wiley & Sons, Ltd.