Table 1 Characteristics of trials included for the main analyses

1999, Liao, L X [14]

39

0.47

0.22

0.73

0.05

 − 0.17

0.27

Empty plastic needle tube

The pain rescue time

2002, Nabeta, T [15]

34

0.41

0.1

0.75

 − 0.18

 − 0.54

0.2

Blunt needle

Visual analog scale (VAS)

2004, Berman, B M [2]

381

0.58

0.5

0.66

 − 0.49

 − 0.56

 − 0.39

Disposable needle

The Western Ontario and McMaster Universities (WOMAC), Osteoarthritis Index

2005, Park, J [16]

116

0.47

0.33

0.61

 − 0.31

 − 0.49

 − 0.13

Blunt needle

Barthel ADL score

2006, Diener, H C [17]

607

0.13

0.05

0.21

0.19

0.11

0.26

Disposable needle

Migraine days

2006, Smith, C [18]

228

0.19

0.1

0.28

0

 − 0.1

0.1

Streiberger needle

Pregnancy rate

2007, Endres, H C [19]

413

 − 0.16

 − 0.27

 − 0.05

 − 0.04

 − 0.16

0.08

Disposable needle

Pain score

2007, Haake, M [20]

774

 − 0.01

 − 0.01

0.01

0.11

0.04

0.18

Disposable needle

Von Korff Chronic Pain Grade Scale7

2008, Alecrim-A, J [21]

36

0.26

0.02

0.5

 − 0.12

 − 0.35

0.11

Disposable needle

Percentage of patients with ≥ 50% reduction in migraine attack frequency

2008, Deng, G [22]

108

0.08

 − 0.24

0.4

0.19

 − 0.13

0.5

Dummy studs

Pain score

2008, Elden, H [23]

115

0.63

0.51

0.75

 − 0.63

 − 0.76

 − 0.51

Streiberger needle

Visual analog scale (VAS)

2008, Goldman, R H [24]

123

0.43

0.24

0.62

 − 0.63

 − 0.8

 − 0.47

Blunt needle

Pain score

2008, Jubb, R W [25]

68

0.17

 − 0.09

0.43

0.29

0.07

0.5

Blunt needle

The Western Ontario and McMaster Universities (WOMAC), Osteoarthritis Index

2008, Smith, C A [26]

364

 − 0.03

 − 0.14

0.09

0.01

 − 0.01

0.12

Disposable needle

Change in Bishop score

2009, Chae, Y Y [27]

20

0.8

0.49

1.11

 − 0.6

 − 0.95

 − 0.25

Park needle

Behavioral Tests frequency

2010, Modlock, J [28]

125

 − 0.1

 − 0.22

0.1

 − 0.05

 − 0.19

0.1

Park needle

Participant had undergone delivery or was in active labour

2010, Tong, Y Q [29]

63

0.32

0.27

0.37

 − 0.65

 − 0.69

 − 0.61

Disposable needle

F-wave minimum latency

2010, White, P [30]

147

0.92

0.84

0.99

 − 0.85

 − 0.96

 − 0.75

Streitberger needle

Visual analog scale (VAS)

2011, Kim, D II [31]

54

0.82

0.63

1.1

 − 0.47

 − 0.78

 − 0.18

Disposable needle

Hot flush scores

2011, Lee, S W H [32]

90

0.22

 − 0.01

0.47

 − 0.56

 − 0.76

 − 0.35

Disposable needle

Visual analog scale (VAS)

2011, Ma, W Z [33]

233

0.92

0.88

0.96

 − 0.87

 − 0.92

 − 0.82

Pragmatic placebo needles

Visual analog scale (VAS)

2011, Smith, C A [34]

92

0.17

 − 0.02

0.37

0.15

 − 0.03

0.33

Blunt needle

Pain score

2012, Chung, K F [35]

20

0

 − 0.52

0.52

0.11

 − 0.43

0.66

Streitberger needle

Hospital Anxiety and Depression Scale (HADS)

2012, Enblom, A [36]

215

0.84

0.75

0.93

 − 0.63

 − 0.76

 − 0.5

Park needle

Consumption of type of antiemetics

2013, Cho, Y J [37]

130

0.07

 − 0.1

0.24

 − 0.23

 − 0.39

 − 0.08

Blunt needle

Visual analog scale (VAS)

2013, Choi, S M [38]

188

0.21

0.1

0.32

 − 0.11

 − 0.23

0

Disposable needle

Total Nasal Symptom Score (TNSS)

2014, Itoh, K [39]

16

0.5

0

1

 − 0.5

 − 1

0

Blunt needle

The pain intensity

2014, Mao, J J [40]

41

0.43

0.17

0.69

0.15

 − 0.14

0.44

Streitberger needle

Pain score

2015, Chen, X Y [41]

30

0.7

0.44

0.96

 − 1

0

0

Streitberger needle

Knee Injury and Osteoarthritis Outcome

Score (KOOS)

2015, Chung, K F [42]

90

0.1

0.01

0.19

 − 0.03

 − 0.16

0.09

Streitberger needle

Insomnia Severity Index score

2015, Gamermann, P W [43]

58

1

0

0

 − 1

0

0

Disposable needle

Visual analog scale (VAS)

2016, Greenlee, H [44]

63

0.67

0.42

0.92

 − 0.82

 − 1.02

 − 0.62

Park needle

Brief Pain Inventory-Short Form (BPI-SF)

2016, Liu, Z S [45]

1072

0.8

0.68

0.92

 − 0.78

 − 0.91

 − 0.66

Disposable needle

Complete Spontaneous Bowel Movements (CSBMs)

2018, Deng, G [46]

60

0.17

 − 0.13

0.47

 − 0.1

 − 0.38

0.19

Disposable needle

MD Anderson Symptom Inventory (MDASI)

2018, Liu, Z S [47]

360

0.89

0.83

0.94

 − 0.9

 − 0.95

 − 0.84

Blunt needle

Menopause Rating Scale (MRS)

2018, Qin, Z S [48]

68

0.76

0.6

0.93

 − 0.53

 − 0.75

 − 0.31

Pragmatic placebo needles

National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI)

2018, Smith, C A [49]

848

0.18

0.12

0.25

0.06

 − 0.01

0.13

Park needle

Pregnancy rate

2019, Huang, Z L [50]

46

0.74

0.53

0.95

 − 0.67

 − 0.9

 − 0.44

Blunt needle

Visual analog scale (VAS)

2019, Kargozar, R [51]

72

0.94

0.84

1.03

 − 1

0

0

Disposable needle

Hot flashes and the change in the quality of life (MENQOL)

2019, Zheng, Z [52]

77

0.3

0.1

0.52

 − 0.11

 − 0.4

0.14

Disposable needle

The dosage of opioid medicine (OM)

2020, Kong, J T [53]

121

0.5

0.31

0.68

0.2

 − 0.07

0.5

Streiberger needle

Pain score

2020, Lee, B [54]

150

0.65

0.5

0.83

 − 0.26

 − 0.52

0.01

Park needle

Insomnia Severity Index (ISI) score

2020, Li, S S [55]

84

0.38

0.21

0.55

 − 0.14

 − 0.36

0.08

Streiberger needle

Pittsburgh Sleep Quality Index (PSQI)

2020, Lin, Z X [56]

99

0.96

0.87

1.04

 − 0.59

 − 0.82

 − 0.36

Blunt needle

Frequency of urgency urinary incontinence (UUI)

2020, Qin, Z S [57]

80

0.39

0.25

0.54

 − 0.31

 − 0.48

 − 0.14

Disposable needle

The Modified Roland-Morris Disability Questionnaire (RMDQ)

2020, Xu, S B [58]

120

0.74

0.62

0.85

 − 0.68

 − 0.81

 − 0.56

Streiberger needle

Change of migraine days

2020, Yang, J W [59]

278

0.51

0.38

0.64

 − 0.55

 − 0.68

 − 0.42

Disposable needle

Response rate

2020, Zhang, L X [60]

96

0.54

0.37

0.72

 − 0.44

 − 0.63

 − 0.24

Park needle

Pittsburgh Sleep Quality Index (PSQI)

2021, Kim, K W [61]

120

0.19

0.03

0.41

0.25

0.16

0.34

Park needle

High-density lipoprotein (HDL)

2021, Kim, M [62]

30

0.64

0.26

1.02

 − 0.77

 − 1.08

 − 0.46

Park needle

17-items HRDS

2021, Li, H [63]

120

0.66

0.5

0.81

 − 0.36

 − 0.56

 − 0.16

Blunt needle

Montreal Cognitive Assessment(MoCA)

2021, Lynning, M [64]

44

0.33

0.03

0.63

0.22

 − 0.05

0.5

Streiberger needle

Functional Assessment of Multiple Sclerosis (FAMS)

2021, Park, J G [65]

32

0.5

0.14

0.86

0.12

 − 0.28

0.53

Park needle

SCORing Atopic Dermatitis index score (SCORAD)

2021, Rona, M R [66]

28

1

0

0

0.12

 − 0.41

0.66

Disposable needle

Visual analog scale (VAS)

2021, Tu, J F [67]

442

0.63

0.57

0.69

 − 0.45

 − 0.55

 − 0.35

Disposable needle

The Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index-Function

2021, Yeung, W F [68]

140

0.34

0.21

0.48

 − 0.13

 − 0.27

0.01

Streitberger needle

Hospital Anxiety and Depression Scale (HADS)

2021, Zheng, Y J [69]

130

0.49

0.32

0.67

0.33

0.14

0.53

Disposable needle

Spontaneous Bowel Movements (SBMs)

2022, Fan, J Q [70]

60

 − 0.13

 − 0.43

0.16

0.2

 − 0.1

0.49

Disposable needle

Hamilton Anxiety Rating Scale (HAM-A)

2022, Qi, L Y [71]

90

 − 0.27

 − 0.49

 − 0.06

0.19

 − 0.03

0.5

Blunt needle

Response rate

2022, Taras, I U [72]

120

0.27

0.11

0.42

0.1

 − 0.04

0.24

Self-adhesive tape

Pain score

2022, Tu, J F [73]

80

0.15

0.06

0.24

0.08

0

0.14

Disposable needle

Visual analog scale (VAS)

2022, Wang, Y [74]

249

0.33

0.2

0.47

 − 0.17

 − 0.32

 − 0.02

Disposable needle

The time to first defecation

2022, Yin, X [75]

180

0.5

0.4

0.7

 − 0.4

 − 0.6

 − 0.3

Streitberger needle

Pittsburgh Sleep Quality Index (PSQI)

2022, Zeng, D [76]

169

0.53

0.38

0.68

0.02

 − 0.12

0.16

Disposable needle

Northwick Park Neck Pain Questionnaire (NPQ)