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Table 3 Subgroup analyses of the regression measurement, time period, region, study type, LDH level, imaging method and patient count

From: The incidence of regression after the non-surgical treatment of symptomatic lumbar disc herniation: a systematic review and meta-analysis

  Included studies (n) Number of patients Incidence (95% CI) P value*
With Regression Total
Measurement 38 1425 2219 63%(0·49–0·77) 0.01
 Qualitative 25 627 1314 54% (0·37–0·70)
 Quantitative 13 798 905 81% (0·69–0·91)
Time period 38 1425 2219 63%(0·49–0·77) 0.87
 Before 2000 15 353 565 65% (0·55–0·75)
 2000–2009 11 280 530 57% (0·29–0·83)
 2010–2019 12 792 1124 66% (0·35–0·91)
Region 38 1425 2219 63%(0·49–0·77) 0.97
 Asia 19 879 1309 63% (0·40–0·83)
 Europe 14 459 756 65% (0·43–0·85)
 North America 5 87 154 60% (0·22–0·92)
Study type 30a 1315 1965 65%(0·48–0·80) 0.14
 RCT 5 125 421 37% (0·00–0·88)
 Prospective 20 588 882 67% (0·57–0·77)
 Retrospective 5 602 662 84% (0·65–0·97)
LDH level 29b 1241 1667 72% (0·58–0·84) 0.17
 Single 22 1103 1340 78% (0·67–0·87)
 Single/multiple 7 138 327 51% (0·17–0·86)
Imaging method 37c 1416 2208 63%(0·48–0·76) 0.97
 CT 8 202 343 63% (0·46–0·79)
 MRI 29 1214 1865 63% (0·45–0·79)
Countingd 38 1425 2219 63%(0·49–0·77) 0.33
 A 30 1279 2018 61% (0·44–0·77)
 B 8 146 201 72% (0·59–0·83)
  1. *P value is from the test for subgroup differences (random effects model)
  2. aEight studies did not report study type
  3. bNine studies did not report LDH level
  4. cOne study used CT at basline and MRI at follow-up
  5. dCounting. A. The number of patients with regression was reported and was extracted from the publication. B. For studies that recorded the number of patients by the regression proportion or size interval but did not define the interval of non-regression or report the number of patients without regression, we regarded the lowest interval as the no regression range, and the number of patients outside of this interval was considered the number of patients with regression