Reliability and validity of the M. D. Anderson Symptom Inventory–Spine Tumor Module

Abstract

Object Tumors involving the spine have unique associated neurological symptoms. The occurrence of spine-related symptoms has been shown to predict treatment course and survival in several studies conducted in patients with solid tumors and consequent spinal cord dysfunction. Currently, no instrument that measures both neurological and cancer-related symptoms exists for patients with spine tumors. The objective of this study was to develop a reliable and valid self-reporting instrument for patients with spine tumors. Methods Patients with diagnosed tumors involving the spine (both primary and metastatic) participated in this study. Data collection tools included a patient-completed demographic data sheet, an investigator-completed clinician checklist, and the core M. D. Anderson Symptom Inventory to which were added 16 neurological symptoms (M. D. Anderson Symptom Inventory–Spine Tumor Module [MDASI-SP]). The authors evaluated the reliability and validity of the MDASI-SP in patients with spine tumors. Results One hundred twenty-six patients participated in the study. Participants were primarily white (73%) males (53%) with metastatic spine tumors (76%). They ranged in age from 18–81 years (median 56 years). Cognitive debriefing of the MDASI-SP was conducted showing the instrument was clear, concise, and easily understood by patients. The most severe core symptoms were pain, fatigue, numbness, disturbed sleep, and distress. The most severe spine module symptoms were spine pain, numbness, weakness in the legs, neck stiffness, and changes in bowel or sexual function. The mean symptom severity of items as well as a cluster analysis was used to reduce the number of total items to 18 (5 spine module items). Regression analysis showed that 57.4% of the variability in symptom interference with daily function was explained by the final instrument. Factor analysis was performed to determine the underlying constructs being evaluated by the symptom items. The 18-item MDASI-SP measures 4 underlying constructs including a disease, an autonomic, a constitutional/treatment, and an emotional factor. The internal consistency (reliability) of the MDASI-SP was 0.946, and the instrument was sensitive to disease severity based on the Karnofsky Performance Scale (KPS). The mean symptom severity was 1.52 for those with good KPS scores (80–100) versus 2.46 for those with poor scores (p < 0.01). The instrument was also sensitive to neurological status according to the Frankel grade (p < 0.001) and inpatient status (p < 0.01). Conclusions The 18-item MDASI-SP demonstrated validity and reliability in patients with spine tumors as a composite measure of disease-related symptoms. This instrument can be used to describe symptom occurrence throughout the disease trajectory and to evaluate interventions designed for symptom management.