Reliability and first validity of the inner correspondence questionnaire for painting therapy (ICPTh) in a sample of breast cancer patients.

Objectives Art therapy (ArT) such as mindfulness-oriented painting therapy is increasingly used in psychosomatic, oncological integrative and rehabilitative medicine. Though it remains unknown how ArT works, we hypothesize that an engaged participation with painting ('Inner-Correspondence') contributes to improved symptom scores. In the context of a comprehensive cohort study for breast cancer survivors with cancer-related fatigue, we developed a patient-reported outcome measure to assess 'Inner Correspondence' with painting therapy and conducted a first validation study. Design A 24-item questionnaire on 'Inner Correspondence' (ICPTh) was administered after ten weeks of intervention and at six month followup together with concurrent scales (Inner Correspondence and Peaceful Harmony, Cancer Fatigue Scale, Hospital Anxiety and Depression Scale, Internal Coherence Scale). Statistical assessment included reliability- and factor analyses. Results A total of n = 68 BC (mean age, 58.2 years, SD = 8.7) participated in the preliminary validation study. Exploratory factor analysis revealed a robust 22-item scale with an unambiguous four-factor solution explaining 78% of total variance and the following subsales: 1) therapy congruence and relaxation (11 items), 2) inner development and mood (6 items), 3) artistic skill (3 items) and 4) task congruence (2 items). The 22-item ICPTh yielded high reliability (Cronbach's alpha = .966, item-total correlation = .497 - .883, test-retest reliability = .888). Conclusions We present a reliable instrument to measure 'Inner Correspondence' with painting therapy. Due to the small sample size and sample selection further validation studies are indicated.