Disclosures: Reza Ehsanian, MD, PhD: No financial relationships or conflicts of interest
Objective: Assess if Numeric Rating Scale (NRS) pain scores are normally distributed in a cohort of patients with axial spine pain pre- and post-intervention.
Design: Retrospective review from four different academic medical centers of prospectively collected data. Setting : Outpatient academic medical center. Participants : 150 patients presenting for confirmation that the source of their axial spine pain was the facet joint.
Interventions: Medial branch blocks (MBBs) with 2% lidocaine or 0.5% bupivacaine.
Main Outcome Measures: Numeric Rating Scale (NRS) pain scores from a uniform pain diary administered to consecutive patients after undergoing MBBs. The pain diary assessed NRS score immediately pre-injection and at 12 different time points post-injection up to 48 hours. D’Agostino & Pearson test was used to test for normality of the data at all time points.
Results: 150 pain diaries were reviewed, with 1,883/1,950 (96.5%) of the potential NRS scales with complete data available. Pre-injection, NRS scores passed normality test (K2 0.655, p=0.72). 30 minutes post injection, during the physiologic action of the injected anesthetic, NRS scores did not pass the test for normality (K2 16.55, p = 0.0003). At all other time points, NRS scores did not pass test for normality, with K2 scores ranging from 9.70 – 17.62 (p= 0.0001 – 0.008). Conclusions: MBBs are a strong model to evaluate normality of NRS scores in patients with axial spine pain, as there are known responders and non-responders to this spine intervention. While NRS scores are normally distributed prior to the intervention, post-intervention the data does not pass the test for normality at any time point. Appropriate statistical considerations should be made when determining primary outcomes in future spine research protocols.
Level of Evidence: Level III
To cite this abstract in AMA style:
Ehsanian R, Kennedy D, Nagpal AS, Patel J, Zheng P, McCormick Z, Schneider B. Non-Normal Distribution of Pain Scores in Patients with Axial Spine Pain After Medial Branch Block [abstract]. PM R. 2020; 12(S1)(suppl 1). https://pmrjabstracts.org/abstract/non-normal-distribution-of-pain-scores-in-patients-with-axial-spine-pain-after-medial-branch-block/. Accessed May 31, 2025.« Back to AAPM&R Annual Assembly 2020
PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/non-normal-distribution-of-pain-scores-in-patients-with-axial-spine-pain-after-medial-branch-block/