People live longer than ever before. This desirable progress puts healthy ageing on the agenda, we would like to live longer while still staying healthy, active and able to enjoy life. Unfortunately, many elderlies get symptoms that prevent them from this. A disease with such symptoms is Lumbar Spinal Stenosis (LSS), which mainly afflicts people over 60 years old. It comes with pain in back and legs that worsens by standing and walking, with pain relief upon sitting and bending forward. This puts a considerable strain on patients' walking ability, with patients experiencing problems with exercising and leisure activities. Physical activity is significantly reduced, a recent study shows that those persons spend 82% of their time in sedentary mode, compared to 35% in healthy adults over 60 years.
Walking ability in clinical research regarding LSS patients is assessed mainly by Patient Reported Outcomes (PROs) and walking tests. The PRO most used is the Oswestry Disability Index (ODI), other PROs include the Swiss Spinal Stenosis Questionnaire (SSSQ) and the Roland Morris Disability Questionnaire (RMDQ). PROs have the disadvantage of being subjective, with factors influencing the answers such as response shift and psyche. There is also research that suggests that the patients' perspective is not fully described by these questionnaires.
Several objective walking tests are used to assess walking ability. The Self-Paced Walking test has been suggested as the gold standard. They provide continuous data and are objective but may be time consuming. They report patients' walking capacity- defined as patients' walking ability in a standardized setting on a single testing occasion.
The question is, how do the PROs and the walking tests relate to walking activity in daily living, also called walking performance? It seems the ODI associates to walking tests, the ODI might thereby be reflecting walking capacity. We do not know if the PROs or the walking tests reflect walking performance. There are multiple factors which influences walking performance. For example, personal factors, contextual factors, and diseases like lumbar spinal stenosis. Treatment for spinal stenosis could improve the results of a walking test, but not necessarily increase walking ability in daily living.
Knowledge is scarce on walking performance in patients with LSS. Accelerometers have been used for measuring physical activity and steps in a wide range of research areas, including LSS. They are small wearable sensors that register accelerations. The raw data on accelerations can then be transformed by mathematical algorithms into variables, such as number of steps taken. Studies on accelerometer-based step counts in older people have shown it to be an accurate measure. But the accuracy of the step count depends much on where the accelerometer is placed, how the raw accelerometer data is transformed and traits of the person wearing it, such as gait speed, gait impairments and age. Some studies have used accelerometers to measure step count in LSS patients. But the method for accelerometer monitoring in patients with LSS is not yet fully developed, validated and standardized. There is no research investigating the optimal anatomical placement for accurate step detection using the selected population.
To identify what interventions helps patients with lumbar spinal stenosis to increase walking ability in their daily living, we need a valid and ready-to-use measure of walking performance. Only then can research on LSS help patients to a healthy and active ageing.
Study Aim and Objectives
The aim of the study is to develop a valid and feasible accelerometer-based outcome measure of walking performance in patients with lumbar spinal stenosis.
The study has four objectives:
• The first objective is to develop an accelerometer measurement method that provides an accurate and feasible outcome measure of walking in a standardized environment.
• The second objective is to test the validity of the outcome measure by examine whether it can discriminate between walking performance in healthy subjects and patients with lumbar spinal stenosis.
• The third objective is to further test the validity by evaluate the accelerometer outcome measure in the context of patients' walking capacity, commonly used PRO's and self-reported walking.
• The fourth objective is to test the outcome measures' ability to evaluate change before and after surgery.