Validation of the German version of the Brief Pain Inventory

The Brief Pain Inventory is a comprehensive instrument for pain assessment and has been validated in several languages. A validated German version was not available until now. From March to May 1995 all outpatients of the pain clinic of the Department of Anesthesiology completed a questionnaire with the German versions of the Brief Pain Inventory (BPI) and the SF-36 quality-of-life questionnaire. The BPI was repeated after the consultation. The physician assessed the performance status score of the Eastern Cooperative Oncology Group (ECOG). The questionnaire was completed by 151 patients. Forty-two patients were excluded from evaluation for methodological reasons, so 109 patients were evaluated. As in the original version of the BPI, factor analysis showed a common factor for pain intensity and a second factor for pain-related interference with function. The comparative fit index of 0.86 confirmed this model. Responses before and after consultation correlated closely for the sum scores of the pain intensity items (Perarson correlation r = 0.976) as well as for the interference with function items (r = 0.974). Pain intensity in the BPI correlated with bodily pain in the SF-36 (r = 0.585). Sum scores of the pain interference items were higher in patients with deteriorated ECOG performance status, whereas sum scores of the intensity items were not changed. Validity and reliability of the German BPI were comparable to the original version. The BPI may be advantageous for palliative care patients, as it places only a small burden on the patient and offers easy criteria for evaluation. However, further research is needed to differentiate the impact of pain-related and disease-related interference with function on the BPI, and to find an algorithm for the evaluation of the BPI when values are missing.