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Table 2 Comparison of preoperative and postoperative VAS scores in the studied groups

From: Surgical outcomes of decompression alone versus transpedicular screw fixation for upper lumbar disc herniation

  Groups Mann–Whitney U test
Group 1
N=22
Group 2
N=24
p value
VAS score
 Preoperative Median 8.0 7.0 0.155
IQR 7.0–9.0 7.0–8.0
Mean rank 26.32 20.92
 Immediately postoperative Median 2.0 2.0 0.727
IQR 2.0–3.0 2.0–3.0
Mean rank 24.14 22.92
 7 days after the operation Median 2.0 2.0 0.231
IQR 2.0–2.0 2.0–2.5
Mean rank 21.45 25.38
 3 months after the operation Median 3.0 3.0 0.880
IQR 2.0–3.0 2.0–3.0
Mean rank 23.77 23.25
 6 months after the operation Median 3.0 2.0 0.474
IQR 2.0-3.0 2.0-3.0
Mean rank 24.80 22.31
Friedman test** <0.001* <0.001*  
  1. *Significant at p<0.05
  2. **Pairwise comparison of VAS score (Wilcoxon-signed rank) in group 1 revealed significant differences between all-time points (p<0.05) except immediately postoperative VAS vs 6 months after the operation (p=0.132) and 3 months vs 6 months after the operation (p= 0.564), whereas in group 2, there were significant differences between preoperative VAS and each of immediately postoperative VAS, 7 days VAS, 3 months VAS, and 6 months VAS. Additionally, there was a significant difference between 7 days VAS and 3 months VAS (p<0.05). Otherwise, no significant differences between other time points (p>0.05)