Linguistic validation of the DN4 for use in international studies.

Objectives: Traditionally, pain is divided into two main groups: nociceptive pain due to an excess of nociception and neuropathic pain associated with an injury or dysfunction of the central or peripheral nervous system. The French neuropathic pain group has developed a specific questionnaire, the DN4, to help clinicians in the differential diagnosis of neuropathic and non-neuropathic pain. In order to allow this questionnaire to be used in international studies, it has been translated and linguistically validated into Dutch, German, Greek and Hungarian, using a well-established procedure.
Methods: The same method was used for each country and involved four stages: (1) two forward translations followed by comparison and reconciliation of the translations, (2) one backward translation, (3) review by an expert clinician, and (4) cognitive testing of the first seven items on patients.
Results: The translation work produced three types of situations. Either the original wording could be translated literally or semantic issues were discussed as the original wording was not always sufficiently clear and had to be clarified by adding an explanation, or, in the case of idiomatic phrases such as "pins and needles", it was necessary to use different expressions, the challenge being to retain the original concept while doing so. The versions proposed to patients and experts were well understood.
Conclusion: The DN4 items were linguistically validated in each of the target languages, thus providing the means for standardising the diagnosis of neuropathic pain and pooling the data collected during clinical research in the different countries involved.