The German version of the body image scale: Validation and item response analysis in cancer patients

To translate the cancer-specific Body Image Scale (BIS) into German and assess its psychometric properties.

The BIS was translated in accordance with current guidelines. In a prospective, cross-sectional two center study (psychosocial counselling center for cancer patients Leipzig, oncological inpatient ward Berlin), we assessed composite reliability and factor structure using confirmatory factor analysis. Additional item response theory (IRT) modelling was performed. Convergent validity was assessed via correlation with the Body Appreciation Scale (BAS) as well as psychological symptom burden (PHQ-9, GAD-2 and Distress Thermometer). Discriminant validity was assessed via demographic and clinical group comparisons.

677 patients participated (response rate 78%). Composite reliability was 0.95 and the one-factor structure was confirmed (standardized root mean square residual = 0.051, average variance extracted ≥50%, no indications of local dependence). In IRT models, all items had a discriminating power above the established threshold of b = 0.5 and relatively high "difficulty" parameters (b = 0.89-2.06). The BIS was negatively correlated with the BAS (rho = -0.62, p < 0.001) and positively with psychological symptom burden (e.g. PHQ-9: rho = 0.49, p < 0.001). Patients who were younger, female, had undergone chemotherapy, radiotherapy or surgery and those who were distressed by fatigue, their appearance or sexual problems had significantly higher BIS scores.

The German version of the BIS is a valid tool to assess BID in patients with cancer that is now available for clinical or research contexts.