Newfound compassion after prostate cancer: a psychometric evaluation of additional items in the Posttraumatic Growth Inventory

The most widely used measure of posttraumatic growth (PTG) is the Posttraumatic Growth Inventory (PTGI). Qualitative research indicates the importance of increased compassion as a result of struggling with challenges presented by cancer and treatments. However, current PTG measures may not adequately assess compassion.

A cross-sectional survey of 514 prostate cancer survivors assessed the PTGI and Dispositional Positive Emotional Scale (DPES). Five additional PTG items were derived from previous qualitative research to assess increased compassion.

After removing eight items with complex loadings, a principal components analysis with oblimin rotation revealed a six-component structure. A clear delineation was seen between components relating to compassion, new possibilities, relating to others, personal strength, appreciation of life and spiritual change. Compassion accounted for 48.9 % of variance in data, with the overall model accounting for 79.9 % of variance. Strong factorability was demonstrated through Kaiser–Meyer–Olkin (0.92) and Bartlett's test of sphericity (approximate χ ² = 5,791.85, df 153, p < 0.001). The six-component structure was validated with a confirmatory factor analysis. Strong internal consistency was evidenced through Cronbach's alpha coefficients ranging from 0.74 to 0.90 for subscales, and item-to-total correlations and inter-item correlations exceeded accepted thresholds of 0.50 and 0.30, respectively. Convergent validity was acceptable between the PTGI compassion subscale and DPES (r = 0.50).

Compassion is a highly salient PTG domain after prostate cancer. Further studies can explore this construct with more heterogeneous samples of cancer types and gender.