The North American Spine Society Lumbar Spine Outcome Assessment Instrument: translation and psychometric analysis of the German version in rehabilitation patients with chronic back pain

The "Lumbar Spine Outcome Assessment Instrument", developed by the North Am erican Spine Society (NASS), was translated into German. Its psychometric p roperties were tested in a group of rehabilitation patients with chronic, u nspecific back pain, and in a comparison group of patients in cardiologic r ehabilitation. With a Cronbach's alpha of 0.92, internal consistency was high. Principal c omponent analysis revealed that the German version of the NASS instrument s urveys the factors "back pain", "neurologic symptoms", and "impairments". A strong correlation with other measures of functional impairment (FFbH-R, I RES) indicates a high concurrent validity of the NASS instrument. After thr ee weeks of inpatient rehabilitation, sensitivity to change could be demons trated for the summary score of the instrument. This significant change was primarily due to moderate effects in the factor "back pain". In our study population, the factor "impairments" did not show a significant change. On the basis of these results, the German version of "The North American Sp ine Society Lumbar Spine Outcome Assessment Instrument" can be described as a reliable and valid instrument for measuring back pain, related neurologi c symptoms, and back pain-induced impairments in rehabilitation patients. B ecause the factor "impairments" is not sensitive to change within three wee ks of rehabilitation, the instrument is only partly suitable for measuring shortterm outcome in rehabilitation patients. Further research is needed to determine if the instrument is useful for middle- and long-term outcome me asurement in rehabilitation.