Validation of the German version of the North American Spine Society (NASS) cervical and lumbar spine outcome instrument.

Background: Pain and functional limitations are the chief symptoms in patients with back pain. However, standardized assessment of these domains are still not commonplace in clinical practice. The objective of this study was the cultural adaptation and validation of the North American Spine Society (NASS) Lumbar Spine Outcome Assessment Instrument for German speaking patients with back pain. Methods: Translation and backtranslation of the NASS instrument was performed according to international recommendations. 56 consecutive inpatients with a confirmed diagnosis of dorsopathia completed a German version of the NASS instrument, the SF-36 and an established German instrument for back patients (FFbH-R). All patients completed the questionnaires 48 hours apart to assess test-retest reliability. Validity was assessed through correlation with corresponding subscales of the SF-36, the FFbH-R and a 0-10 pain numeric rating scale. Internal consistency and item-to-scale correlation served as statistics of reliability. Results: The two subscales of the NASS Instrument for cervical and lumbar problems correlate significantly with the corresponding subscales of the FFbH-R and the SF-36 (r = 0.28-0.83, p < 0.05) and 0.39-0.68 (p < 0.05) with a pain numeric rating scale. Test-retest reliability demonstrated intraclass correlation coefficients between 0.82 to 0.89. Conclusion: The German version of the NASS Cervical and Lumbar Spine Outcome Assessment Instrument allows the standardized assessment of pain, functional limitations and neurogenic symptoms in patients with back pain and the international comparison of health states and therapeutic outcomes.