Translation and discriminative validation of the STarT Back Screening Tool into Danish

The STarT Back Screening Tool (STarT) is a nine-item patient self-report questionnaire that classifies low back pain patients into low, medium or high risk of poor prognosis. When assessed by GPs, these subgroups can be used to triage patients into different evidence-based treatment pathways. The objective of this study was to translate the English version of STarT into Danish (STarT-dk) and test its discriminative validity.

Translation was performed using methods recommended by best practice translation guidelines. Psychometric validation of the discriminative ability was performed using the Area Under the Curve statistic. The Area Under the Curve was calculated for seven of the nine items where reference standards were available and compared with the original English version.

The linguistic translation required minor semantic and layout alterations. The response options were changed from "agree/disagree" to "yes/no" for four items. No patients reported item ambiguity using the final version. The Area Under the Curve ranged from 0.735 to 0.855 (CI95% 0.678-0.897) in a Danish cohort (n = 311) and 0.840 to 0.925 (CI95% 0.772-0.948) in the original English cohort (n = 500). On four items, the Area Under the Curve was statistically similar between the two cohorts but lower on three psychosocial sub-score items.

The translation was linguistically accurate and the discriminative validity broadly similar, with some differences probably due to differences in severity between the cohorts and the Danish reference standard questionnaires not having been validated. Despite those differences, we believe the results show that the STarT-dk has sufficient patient acceptability and discriminative validity to be used in Denmark.