A test of the psychometric properties of the cancer locus of control scale in Greek patients with advanced cancer

Objective The study aimed to assess the psychometric properties of the Cancer Locus of Control (CLOC) scale on a Greek sample of advanced cancer patients. Methods The scale was translated with the forwardbackward procedure to Greek. The CLOC scale was administered to 140 advanced cancer patients. It was administered twice, with a 3-day interval, to 100 (of the 140) eligible patients with advanced cancer. Together with the CLOC scale, the patients also completed the Greek Mental Adjustment to Cancer (G-MAC) scale. Confirmatory factor analysis was carried out using the AMOS 7.0 analysis. The reliability was assessed by the internal consistency (Cronbach's a coefficients), testretest (Spearman's r value) of the instrument, and inter-item correlations. Construct validity was assessed using the G-MAC scale, interscale correlations, itemscale correlations, and scalestotal correlations. Results The homogeneity of the subscales proved to be satisfactory (a coefficient ranged from 0.713 to 0.786). Overall testretest reliability was satisfactory at p<0.0005. Construct validity has shown moderate correlations with G-MAC p<0.0005. Interscale and inter-item correlations were satisfactory at p<0.05. Conclusions The results suggest that the Greek version of CLOC administered in cancer patients treated in a palliative care unit is a reliable and valid clinical instrument. Copyright (c) 2011 John Wiley & Sons, Ltd.