The following is a summary of “Normality Analysis of Numeric Rating Scale Scores in Patients with Chronic Axial Spine Pain Before and After Medial Branch Blocks: a Multicenter Study,” published in the May 2024 issue of Pain by Ehsanian et al.
Traditional pain analysis methods presume normal pain score distribution for comparing pre- and post-intervention effects.
Researchers conducted a retrospective study to investigate whether the Numeric Rating Scale (NRS), particularly the NRS-11, scores follow a normal distribution in a real-world group of adults with chronic axial spine pain before and after receiving pain medication.
They reviewed four academic medical centers, analyzing collected data from a standard pain diary given to consecutive patients following medial branch blocks. Diary evaluated NRS-11 scores just before the injection and at 12 various intervals afterward, extending up to 48 hours. D’Agostino-Pearson tests were applied to assess normality across all time points.
The results showed that 150 pain diaries, despite normally distributed pre-injection NRS-11 scores (K2 = 0.655, P=0.72), post-injection NRS-11 data was not normally distributed (K2 = 9.70-17.62, P=0.0001-0.008).
Investigators concluded that the study’s NRS-11 scores deviated from a normal distribution after the intervention, highlighting the need for alternative statistical methods for accurate pain data analysis.
Source: academic.oup.com/painmedicine/advance-article-abstract/doi/10.1093/pm/pnae041/7679669
