Prospective analysis of clinical evaluation and self-assessment by patients after decompression surgery for degenerative lumbar canal stenosis

Abstract

Background context: Objective measures including neurological findings, radiographic evaluation, and the Japanese Orthopaedic Association (JOA) score are commonly used for the evaluation of surgical outcomes. Because many surgeries are performed primarily to improve quality of life, a patient's subjective evaluations are also important for accurately assessing surgical outcomes. Currently available instruments for assessing quality of life include the Short-Form 36 (F-36), the Oswestry disability index (ODI), and the visual analog scale (VAS) clinical pain scale.

Purpose: The aims of this study were to measure surgical outcomes by using both objective measures and subjective measures including patient self-assessments and psychological changes; to assess the adequacy of the JOA alone for measuring outcome; and to determine which measures, the SF-36v2, ODI, VAS, or JOA correlate with the VAS pain scale score in lumbar canal stenosis.

Study design: We performed a prospective study to measure surgical outcomes for lumbar canal stenosis using traditional objective measures such as neurological findings and subjective measures such as performance of ADLs, patient self-assessments, and psychological changes.

Patient sample: Forty-two surgical patients with a mean age of 66.8+/-10.9 years at the time of surgery were included in the study. All cases were followed for more than 2 years. Surgical indications included no response to conservative treatment and neurological deterioration. Neurological symptoms were classified as nerve root type, cauda equine type, or combined type. We performed surgical decompression at the location of the dural or root indentation by myelography. The concomitant diagnosis causing the spinal stenosis was degenerative spondylolisthesis in 20 cases undergoing posterolateral fusion with pedicle screws.

Outcome measures: Surgical outcomes were assessed by comparing preoperative and 24-month postoperative JOA scores for low back pain, SF-36v2, ODI-v2, and VAS scores. Statistical analysis was performed by using the analysis of variance. A p value<0.05 was considered statistically significant.

Methods: Objective clinical measures, patient self-assessments, and psychological changes were measured before and at 24 months postoperatively. We also examined which measurements correlated with the VAS scale for pain evaluation, thereby relating patient satisfaction to surgery outcome.

Results: All JOA, SF-36v2, ODI-v2, and VAS scores significantly improved postoperatively. The physical component summary (PCS) of the SF-36 v2 showed significant improvement, although all scores remained less than the Japanese norm-based scores (NBSs). The mental component summary (MCS) exhibited such a significant improvement that all postoperative subscales were higher than the Japanese NBS. JOA scores significantly correlated only with postoperative lower-extremity VAS score. All PCS and two MCS scores significantly correlated with the VAS score for low back pain. Parts of the PCS and MCS significantly correlated with the lower-extremity VAS. The ODI significantly correlated with both the preoperative and postoperative VAS scores for low back pain as well as with the postoperative lower-extremity VAS score.

Conclusions: The JOA, SF-36, ODI, and VAS questionnaires are all useful instruments for measuring surgical outcomes. The VAS score is a better assessment of physical rather than mental health. The ODI is more reflective of patients' subjective symptoms. Finally, the SF-36 is particularly informative because it includes questions addressing both psychological and physical status. Therefore, when combined, the SF-36v2, VAS, and ODI scores are a valuable complement to the JOA scores in evaluating outcomes of surgery for lumbar canal stenosis.