Reliability and validity of a Dutch Lymphoedema Questionnaire: Cross-cultural validation of the Norman Questionnaire.

Objective: To perform the cross-cultural validation process of the Dutch Norman Questionnaire (NQ), a questionnaire for the detection and characterisation of breast-cancer related lymphoedema (BCRL) using self-reported signs and symptoms.
Methods: Test-retest reliability and construct (including convergent, divergent and known-groups validity), face and content validity were examined in breast cancer patients with (n = 30) and without (n = 30) lymphoedema. For concurrent validity, first, agreement between the diagnostic item of the NQ and a clinical diagnosis were analysed. Second, correlations between NQ scores and clinical arm volume assessment were tested.
Results: Test-retest reliability was found to be strong to very strong (ICC 0.79-0.96) in the lymphoedema group and moderate to very strong ( ICC 0.64-0.99) in the non-lymphoedema group. Seventeen out of 20 hypotheses on convergent and divergent validity were accepted. There was good face, content and known-groups validity as well. For concurrent validity, agreement between evaluation methods was only 0.462. Moderate correlations were found between 6 out of 9 symptom scores (r = 0.422-0.630) of the NQ and clinical assessment.
Conclusion: The Dutch NQ is a reliable and valid questionnaire for the characterisation of BCRL using self-reported signs and symptoms. Only moderate agreement for the detection of BCRL was found.
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