Translation and adaptation of an international questionnaire to measure usage of complementary and alternative medicine (I-CAM-G)

Background: The growing body of data on prevalence of complementary and alternative medicine (CAM) usage means there is a need to standardize measurement on an international level. An international team has published a questionnaire (I-CAM-Q), but no validation has yet been provided. The aim of the present study was to provide a German measurement instrument for CAM usage (I-CAM-G) which closely resembles the original English version, and to assess it's performance in two potential samples for measuring CAM usage. Methods: The English I-CAM-Q questionnaire was translated into German, and adapted slightly. The resulting I-CAM-G questionnaire was then pre-tested on 16 healthy volunteers, and 12 cognitive interviews were carried out. The questionnaire was employed in a sample of breast cancer patients (N = 92, paper and pencil), and a sample from the general population (N = 210, internet survey). Descriptive analyses of items and missing data, as well as results from the cognitive interviews, are presented in this paper. Results: The translated questionnaire had to be adapted to be consistent with the German health care system. All items were comprehensible, whereby some items were unambiguous (e.g. CAM use yes/no, helpfulness), while others gave rise to ambiguous answers (e.g. reasons for CAM use), or high rates of missing data (e.g. number of times the CAM modality had been used during the last 3 months). 78% of the breast cancer patients and up to 85% of a sample of the general population had used some form of CAM. Conclusions: Following methodologically sound and comprehensive translation, adaptation and assessment processes using recognized translation procedures, cognitive interviews, and studying the performance of the questionnaire in two samples, we arrived at a German questionnaire for measuring CAM use which is comparable with the international (English) version. The questionnaire appropriately measures CAM use, with some items being more appropriate than others. We recommend the development of a short version.