An assessment of the validity and responsiveness of the Numerical Rating Scale version of the Pain Disability Quality-Of-Life Questionnaire-Spine.

ABSTRACT

The Numerical Rating Scale Version of the Pain Disability Quality-Of-Life Questionnaire-Spine (NRS PDQQ-S) is a six question compensate patient reported outcome measure designed for use in the field of minimally invasive interventional spine care. Although acceptable reliability, validity and responsiveness have been confirmed for the Visual Analog Scale version of the PDQQ-S in patients undergoing lumbosacral spine corticosteroid injections and radiofrequency neurotomy, the Numerical Rating Scale version has undergone limited psychometric assessment. The purposes of this study were to define the validity and responsiveness of the NRS PDQQ-S, and to do so in a cohort undergoing an emerging type of spine intervention (platelet rich plasma [PRP] injection). Prospectively gathered pre-and 6months post lumbosacral spine PRP injection(s) NRS PDQQ-S and Oswestry Disability Index (ODI) data were analyzed on 75 patients. NRS PDQQ-S construct validity was evaluated by calculating the correlation with the ODI. Internal responsiveness was estimated for both PDQQ-S and ODI by calculating the effect size (Cohen's d). External responsiveness was estimated by calculating the correlation between the change scores of the NRS PDQQ-S and ODI. Strong statistically significant correlations were documented between the PDQQ-S and ODI questionnaires at pre-PRP injection (r â€‹= â€‹0.67; p<.0001) and 6 months post-PRP injection (r â€‹= â€‹0.82; p<.0001) supporting construct validity. Internal responsiveness was confirmed by large and comparable effect sizes for both the NRS PDQQ-S [1.1 (CI 0.8-1.4)] (1.1) and ODI [0.9 (CI 0.7-1.2)]. External responsiveness was confirmed by the strong correlation between the change scores of the NRS PDQQ-S and ODI [r â€‹= â€‹0.73 (p<.0001)]. This study supports the premise that the NRS PDQQ-S is a valid and responsive instrument that can be used to assess patients with low back pain who are treated with PRP injections.