Special Poster Session 51st International Society for the Study of the Lumbar Spine Annual Meeting 2025

INTRODUCTION:  Lumbar spinal stenosis is a leading cause of pain and disability in older adults.¹ The condition is defined as narrowing of the spinal canal that results in pain, weakness, numbness in the lower limbs when standing or walking, that is reduced when sitting or bending forward. Despite how common the condition is, the quality of the assessment tools used to assess remains unclear. ²

METHODS: Before and after surgery, 124 people [mean age 64.08, SD: 13.94] diagnosed with symptomatic lumbar spinal stenosis who were recommended decompression surgery by a neurosurgeon were assessed. At baseline, 78% of the cohort reported back pain and 100% reported lower neurogenic claudication [lower limb pain, numbness, weakness with walking/standing that was alleviated with lumbar flexion/sitting down]. The assessment included a 30-minute Self Paced Walking Test using a wearable activity monitor. The Oswestry Disability Index [ODI], Physical Function Scale [of the Swiss Spinal Stenosis Questionnaire], iPhone walking application, and a likert recovery scale were also assessed. Up to three assessments were conducted to determine validity, test re-test reliability, and responsiveness. Criterion validity was determined using a Spearman or Pearson correlation coefficient. Test re-test reliability was captured using intraclass correlation coefficient. Responsiveness was captured using an Area Under the Curve [AUC]. The COSMIN quality criteria was used for determining adequate measurement property results.  

RESULTS: Criterion validity [gold standard was the Self Paced Walking Test] was found to be highest for the activity monitor [0.96] and lowest for the ODI walk item [-0.33]. The iPhone walking application [0.93] and activity monitor were the only assessments with adequate criterion validity, with the Physical Function Scale [-0.46], ODI [-0.48] and ODI walk item [-0.33] all having inadequate validity according to COSMIN. Reliability was adequate for all measures except the ODI walk item. Responsiveness was highest for the Self Paced Walking Test [AUC 0.73] and ODI walk item [AUC 0.71]. No other measure had an AUC above 0.70. 68% of the cohort reported a moderate or complete recovery in their symptoms post decompression surgery.

DISCUSSION: Common assessment tools for assessing lumbar spinal stenosis have a mix of adequate and inadequate measurement properties. The activity monitor provides an excellent option for capturing walking distance, but its responsiveness is limited when compared with patient's self-reported recovery. Clinicians and researchers should consider which construct they are wanting to assess for people with lumbar spinal stenosis, as the measurement properties of existing tools are not all adequate.