Table 7 Visual analog scale scores for back pain

Yang et al. 2017 [15]

5.8 ± 0.9

1.0 ± 0.9

5.6 ± 0.8

1.2 ± 1.2

Adogwa et al. 2015 [19]

6.97 ± 2.49

4.55 ± 3.81

7.0 ± 2.44

4.67 ± 3.67

Terman et al. 2014 [21]

7.1 (−)

4.7 (−)

7.1 (−)

4.3 (−)

Wong et al. 2014 [22]

6.37 (−)

1.05 (−)

6.72 (−)

1.70 (−)

Sulaiman et al. 2014 [13]

7.3 (−)

3.2 (−)

7.3 (−)

5.1 (−)

Gu et al. 2014 [24]

7.3 ± 1.2

1.9 ± 0.7

7.4 ± 1.0

1.8 ± 0.6

Brodano et al. 2013 [25]

7.8 ± 1.4

2.3 ± 1.3

8.1 ± 1.5

2.6 ± 1.2

Seng et al. 2013 [26]

5.6 ± 3.3

1.3 ± 0.4

6.2 ± 2.7

0.9 ± 0.3

Cheng et al. 2013 [27]

7.1 ± 0.7

2.9 ± 0.3

7.6 ± 0.5

3.5 ± 0.5

Rodriguez-Vela et al. 2013 [29]

7.04 ± 1.12

3.381 ± 2.69

7.19 ± 2.21

4.611 ± 3.12

Parker et al. 2013 [30]

8.1 ± 2.6

3.3 ± 2.9

8.5 ± 2.2

3.6 ± 2.8

Adogwa et al. 2012 [31]

6.80 ± 2.40

–

6.14 ± 1.67

3.14 (−)

Wang et al. 2012 [32]

6.3 ± 2.5

1.3 ± 0.6

6.0 ± 2.1

1.5 ± 0.5

Lee et al. 2012 [6]

6.3 ± 2.9

2.3 ± 3.0

6.3 ± 2.9

2.4 ± 2.7

Parker et al. 2012 [34]

8.4 ± 1.7

5.5 ± 2.6

9.3 ± 0.9

4.7 ± 3.2

Adogwa et al. 2010 [36]

8.4 ± 1.7

5.5 ± 2.6

9.3 ± 0.9

4.7 ± 3.2

Wang et al. 2010 [37]

7.1 ± 2.4

1.3 ± 0.5

6.9 ± 1.7

1.5 ± 0.4

Villavicen et al. 2010 [42]

7.4 (−)

3.4 (−)

8.0 (−)

3.2 (−)

Shunwu et al. 2009 [38]

6.8 ± 1.2

2.3 ± 1.5

6.8 ± 1.4

3.2 ± 1.2

Wang et al. 2010 [37]

7.2 ± 2.1

0.92 ± 0.5

7.4 ± 1.6

1.1 ± 0.6

Peng et al. 2009 [39]

6 (−)

1 (−)

6.5 (−)

1.2 (−)

Schizas et al. 2008 [41]

7.7 (−)

3.5 (−)

5.0 (−)

2.8 (−)