Methods: Data from VA neurosurgery clinic patients with CSM were obtained from structured interviews and the medical record. Patients were assessed using established CSM severity measures (Nurick, Harsh, and modified Japanese Orthopaedic Association (mJOA) scales), and completed the SF-36 v1.0 (yielding physical component summary [PCS] and mental component summary [MCS] scores), and the QWB-SA v1.04. The validity of the QWB-SA was assessed by comparing QWB-SA scores with CSM-specific severity scales (Nurick, Harsh, mJOA scales) and with validated health status measures (SF-36 PCS and MCS) using Spearman's rho for continuous variables (e.g. PCS) and Cuzick's non-parametric test for trend for ordinal variables (e.g., Nurick scale).
Results: The 46 patients who completed the QWB-SA were predominantly male (93%) and Caucasian (87%) with a median age of 56.1 years (interquartile rage [IR]: 53.4, 63.0); and 31% rated themselves as disabled. The median SF-36 PCS was 25.0 (IR: 21.7, 31.9), MCS was 43.1 (IR: 33.4, 49.7), and QWB-SA was 0.49 (IR: 0.40, 0.55). There was a positive association between QWB-SA scores and better functioning as measured on the Nurick scale (P=0.037), Harsh scale (P=0.038), mJOA scale (P=0.082), mJOA leg subscale (P<0.001), and the SF-36 PCS (P=0.046, rho=0.30) and MCS (P=0.056, rho=0.28).
Conclusions: Patients with CSM have a substantially reduced quality of life as measured with the QWB-SA. The QWB-SA appears to be a valid measure of quality of life in patients with CSM, since higher QWB-SA scores are associated with lower disease severity as measured with CSM-specific instruments and with better health status as measured with the SF-36, a generic health status instrument. Compared with severity scales or health status measures, the QWB-SA has the advantage of providing a health value on a 0-1 ratio scale that can be incorporated into decision analyses and cost-effectiveness analyses.