Clinimetric properties of the EuroQol-5D in patients with chronic low back pain.

BACKGROUND CONTEXT Clinimetric properties of the EuroQol-5D (EQ-5D) in patients with nonspecific chronic low back pain (CLBP) are largely unknown. PURPOSE To study the criterion validity, responsiveness, and minimal clinically important change (MCIC) of EQ-5D in patients with CLBP. STUDY DESIGN Prospective study design carried out in a multispecialist Spine Center in The Netherlands. PATIENT SAMPLE One hundred fifty-one patients with CLBP. OUTCOME MEASURES Quality of life (QOL) was measured with EQ-5D, consisting of two scales: one scale measuring QOL with five categorical questions and the other measuring health state on a visual analog scale (0-100). Criterion measures were disability, measured with the Pain Disability Index (PDI) and the Roland Morris Disability Questionnaire (RMDQ), and pain intensity, measured with a numeric rating scale (NRS). METHODS Pearson correlation coefficients between the EQ-5D and RMDQ, PDI, and NRS were calculated to test the criterion validity. Correlations were interpreted based on predefined criteria. Responsiveness of the EQ-5D was calculated with area under the receiver operating characteristics (ROC) curve. Minimal clinically important change was calculated with the optimal cutoff point under the ROC curve, and sensitivity and specificity were also calculated. RESULTS Correlations between EQ-5D and criterion measures ranged between 0.39 and 0.59 and were considered moderate to good. Areas under the ROC curve ranged from 0.59 to 0.72 depending on the external criterion and EQ-5D subscale. The MCIC was 0.03 points for the categorical scales of the EQ-5D and 10.5 points for the EQ-5D visual analog scale. CONCLUSIONS The EQ-5D is a valid and responsive QOL scale in patients with CLBP.