Guidelines for the Process of Cross-Cultural Adaptation of Self-Report Measures :

Statistical analyses of Differential Item Functioning (DIF) can be used for rigorous translation evaluations. DIF techniques test whether each item functions in the same way, irrespective of the country, language, or culture of the respondents. For a given level of health, the score on any item should be independent of nationality. This requirement can be tested through contingency-table methods, which are efficient for analyzing all types of items. We investigated DIF in the Danish translation of the SF-36 Health Survey, using two general population samples (USA, n = 1,506; Denmark, n = 3,950). DIF was identified for 12 out of 35 items. These results agreed with independent ratings of translation quality, but the statistical techniques were more sensitive. When included in scales, the items exhibiting DIF had only a little impact on conclusions about cross-national differences in health in the general population. However, if used as single items, the DIF items could seriously bias results from cross-national comparisons. Also, the DIF items might have larger impact on cross-national comparison of groups with poorer health status. We conclude that analysis of DIF is useful for evaluating questionnaire translations.

Cross-cultural adaptation and cross-sectional psychometric testing. To develop and validate a cross-cultural version of the Roland-Morris Questionnaire for use in German-speaking patients with low back pain. Clinical research related to the management of back pain would be facilitated enormously if a small number of patient-oriented questionnaires became widely used. If the transposition of a questionnaire from its original cultural context is done by simple translation, it is unlikely to be successful because of language and cultural differences. Therefore, a simple direct translation of a questionnaire from one language to another does not permit its use in clinical trials. The instrument was translated and back-translated, pretested, and reviewed by a committee. The German version of the Roland-Morris Questionnaire was tested in 125 patients with low back pain. The study was conducted at the spa resort at Senftenberg, Austria, which is visited by patients from all countries of German-speaking Europe. Reliability and concurrent construct validity were assessed with Pearson's correlation coefficient on the Roland-Morris Questionnaire scores compared with the scales of the Medical Outcome Study Short Form-36 questionnaire. Pearson's correlation coefficient for test-retest reliability of the German version was r = 0.82 (P = 0.0001), and Cronbach's alpha was 0.81. The concurrent validity was r = 0.81 (Roland-Morris Questionnaire/pain rating; P = 0.0001), r = 0.48 (Roland-Morris Questionnaire/forward bending; P = 0.0001), and r = -0.47 (Roland-Morris Questionnaire/lateral bending; P = 0.0001). Correlation between the functional scales of the Medical Outcome Study Short Form-36 questionnaire and the Roland-Morris Questionnaire sum scores ranged from r = -0.29 (emotional limitations; P = 0.0011) to r = -0.71 (physical limitations; P = 0.0001). Because the German version of the Roland-Morris Questionnaire seems to be reliable and valid for the assessment of the functional status in German-speaking patients with low back pain, the use of this translated instrument can be recommended in future clinical trials.