Scolaris Content Display Scolaris Content Display

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.
Figures and Tables -
Figure 1

Methodological quality summary: review authors' judgements about each methodological quality item for each included study.

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.2 Difference in number of cramps over 2 weeks ‐ random‐effects (minus Connolly 1992).
Figures and Tables -
Figure 2

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.2 Difference in number of cramps over 2 weeks ‐ random‐effects (minus Connolly 1992).

Forest plot of comparison: 2 Quinine versus vitamin E, outcome: 2.1 Difference in number of cramps in 2 weeks ‐ random‐effects (minus Connolly 1992).
Figures and Tables -
Figure 3

Forest plot of comparison: 2 Quinine versus vitamin E, outcome: 2.1 Difference in number of cramps in 2 weeks ‐ random‐effects (minus Connolly 1992).

Forest plot of comparison: 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), outcome: 3.1 Difference in number of cramps in 2 weeks ‐ random‐effects.
Figures and Tables -
Figure 4

Forest plot of comparison: 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), outcome: 3.1 Difference in number of cramps in 2 weeks ‐ random‐effects.

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.7 Participants suffering minor adverse events ‐ fixed‐effect.
Figures and Tables -
Figure 5

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.7 Participants suffering minor adverse events ‐ fixed‐effect.

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.8 Participants suffering specific minor adverse events.
Figures and Tables -
Figure 6

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.8 Participants suffering specific minor adverse events.

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.9 Participants suffering major adverse events.
Figures and Tables -
Figure 7

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.9 Participants suffering major adverse events.

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.10 Participants suffering specific major adverse events (gastrointestinal).
Figures and Tables -
Figure 8

Forest plot of comparison: 1 Quinine versus placebo, outcome: 1.10 Participants suffering specific major adverse events (gastrointestinal).

Comparison 1 Quinine versus placebo, Outcome 1 Difference in number of cramps over 2 weeks (GIV) ‐ fixed‐effect.
Figures and Tables -
Analysis 1.1

Comparison 1 Quinine versus placebo, Outcome 1 Difference in number of cramps over 2 weeks (GIV) ‐ fixed‐effect.

Comparison 1 Quinine versus placebo, Outcome 2 Difference in number of cramps over 2 weeks ‐ random‐effects (minus Connolly 1992).
Figures and Tables -
Analysis 1.2

Comparison 1 Quinine versus placebo, Outcome 2 Difference in number of cramps over 2 weeks ‐ random‐effects (minus Connolly 1992).

Comparison 1 Quinine versus placebo, Outcome 3 Difference in number of cramps according to quinine dose (GIV) ‐ fixed‐effect.
Figures and Tables -
Analysis 1.3

Comparison 1 Quinine versus placebo, Outcome 3 Difference in number of cramps according to quinine dose (GIV) ‐ fixed‐effect.

Comparison 1 Quinine versus placebo, Outcome 4 Difference in cramp intensity (GIV) ‐ fixed‐effect.
Figures and Tables -
Analysis 1.4

Comparison 1 Quinine versus placebo, Outcome 4 Difference in cramp intensity (GIV) ‐ fixed‐effect.

Comparison 1 Quinine versus placebo, Outcome 5 Change in cramp duration (mins) ‐ random‐effects.
Figures and Tables -
Analysis 1.5

Comparison 1 Quinine versus placebo, Outcome 5 Change in cramp duration (mins) ‐ random‐effects.

Comparison 1 Quinine versus placebo, Outcome 6 Difference in number of cramp days over 2 weeks (GIV) ‐ random‐effects (minus Connolly 1992.
Figures and Tables -
Analysis 1.6

Comparison 1 Quinine versus placebo, Outcome 6 Difference in number of cramp days over 2 weeks (GIV) ‐ random‐effects (minus Connolly 1992.

Comparison 1 Quinine versus placebo, Outcome 7 Participants suffering minor adverse events ‐ fixed‐effect.
Figures and Tables -
Analysis 1.7

Comparison 1 Quinine versus placebo, Outcome 7 Participants suffering minor adverse events ‐ fixed‐effect.

Comparison 1 Quinine versus placebo, Outcome 8 Participants suffering specific minor adverse events.
Figures and Tables -
Analysis 1.8

Comparison 1 Quinine versus placebo, Outcome 8 Participants suffering specific minor adverse events.

Comparison 1 Quinine versus placebo, Outcome 9 Participants suffering major adverse events.
Figures and Tables -
Analysis 1.9

Comparison 1 Quinine versus placebo, Outcome 9 Participants suffering major adverse events.

Comparison 1 Quinine versus placebo, Outcome 10 Participants suffering specific major adverse events (gastrointestinal).
Figures and Tables -
Analysis 1.10

Comparison 1 Quinine versus placebo, Outcome 10 Participants suffering specific major adverse events (gastrointestinal).

Comparison 2 Quinine versus vitamin E, Outcome 1 Difference in number of cramps in 2 weeks ‐ random‐effects (minus Connolly 1992).
Figures and Tables -
Analysis 2.1

Comparison 2 Quinine versus vitamin E, Outcome 1 Difference in number of cramps in 2 weeks ‐ random‐effects (minus Connolly 1992).

Comparison 2 Quinine versus vitamin E, Outcome 2 Difference in cramp intensity ‐ fixed‐effect.
Figures and Tables -
Analysis 2.2

Comparison 2 Quinine versus vitamin E, Outcome 2 Difference in cramp intensity ‐ fixed‐effect.

Comparison 2 Quinine versus vitamin E, Outcome 3 Difference in number of cramp days over 2 weeks ‐ random‐effects (minus Connolly 1992).
Figures and Tables -
Analysis 2.3

Comparison 2 Quinine versus vitamin E, Outcome 3 Difference in number of cramp days over 2 weeks ‐ random‐effects (minus Connolly 1992).

Comparison 2 Quinine versus vitamin E, Outcome 4 Participants suffering minor adverse events ‐ random‐effects.
Figures and Tables -
Analysis 2.4

Comparison 2 Quinine versus vitamin E, Outcome 4 Participants suffering minor adverse events ‐ random‐effects.

Comparison 2 Quinine versus vitamin E, Outcome 5 Participants suffering major adverse events ‐ random‐effects.
Figures and Tables -
Analysis 2.5

Comparison 2 Quinine versus vitamin E, Outcome 5 Participants suffering major adverse events ‐ random‐effects.

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 1 Difference in number of cramps in 2 weeks ‐ random‐effects.
Figures and Tables -
Analysis 3.1

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 1 Difference in number of cramps in 2 weeks ‐ random‐effects.

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 2 Difference in cramp intensity ‐ random‐effects.
Figures and Tables -
Analysis 3.2

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 2 Difference in cramp intensity ‐ random‐effects.

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 3 Difference in number of cramp days over 2 weeks ‐ random‐effects.
Figures and Tables -
Analysis 3.3

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 3 Difference in number of cramp days over 2 weeks ‐ random‐effects.

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 4 Participants suffering minor adverse events ‐ random‐effects.
Figures and Tables -
Analysis 3.4

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 4 Participants suffering minor adverse events ‐ random‐effects.

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 5 Participants suffering major adverse events ‐ fixed‐effect.
Figures and Tables -
Analysis 3.5

Comparison 3 Quinine versus a quinine‐vitamin E combination (Q‐Vel), Outcome 5 Participants suffering major adverse events ‐ fixed‐effect.

Summary of findings for the main comparison. Quinine for muscle cramps

Quinine for muscle cramps

Patient or population: patients with muscle cramps
Settings: Mainly outpatients
Intervention: Quinine versus placebo

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect
(95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Comments

Assumed risk

Corresponding risk

Control

Quinine versus placebo

Number of cramps over 2 weeks

The mean number of cramps over 2 weeks in the control groups was
8.8 cramps

The mean Number of cramps over 2 weeks in the intervention groups was
2.45 lower
(1.36 to 3.54 lower)

952
(13 studies)

⊕⊕⊕⊝
moderate1

The difference was statistically significant.

Cramp intensity
(on 3‐point scale; 1=mild; 2=moderate; 3=severe)

The mean cramp intensity in the control groups was
1.2 units

The mean Cramp intensity in the intervention groups was
0.12 lower
(0.2 to 0.05 lower)

666
(7 studies)

⊕⊕⊕⊝
moderate1

The difference was statistically significant.

Participants suffering major adverse events

14 per 1000

15 per 1000
(4 to 35)

See comment

1103
(18 studies)

⊕⊕⊕⊝
moderate2

Risks were calculated from pooled risk differences. The difference was not statistically significant.

Participants suffering minor adverse events

94 per 1000

127 per 1000
(94 to 154)

See comment

969
(16 studies)

⊕⊕⊕⊝
moderate3

Risks were calculated from pooled risk differences. The difference was statistically significant.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1 There were significant shortcomings in study design in some trials, but the majority of those included in this meta‐analysis were of moderate to high quality
2 Major adverse events were defined as those being severe enough to warrant participant withdrawal from the trial. As specific hypersensitivity reactions are so rare, larger studies are needed to clarify the incidence of such adverse events in particular. Some trials did not pre‐specify adverse events as an outcome but simply reported them retrospectively, thus compromising slightly on the quality of evidence.
3 Minor adverse events were defined as being those that did not warrant participant withdrawal from the trial. Some trials did not pre‐specify adverse events as an outcome but simply reported them retrospectively, thus compromising slightly on the quality of evidence. Otherwise, a well reported outcome.

Figures and Tables -
Summary of findings for the main comparison. Quinine for muscle cramps
Summary of findings 2. Quinine versus vitamin E for muscle cramps

Quinine versus vitamin E for muscle cramps

Patient or population: patients with muscle cramps
Settings: Outpatients
Intervention: Quinine versus vitamin E

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect
(95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Comments

Assumed risk

Corresponding risk

Control

Quinine versus vitamin E

Number of cramps over 2 weeks

The mean number of cramps over 2 weeks in the control groups was
7.22

The mean Number of cramps over 2 weeks in the intervention groups was
0.24 lower
(1.29 lower to 0.81 higher)

513
(3 studies)

⊕⊕⊝⊝
low1,2

The difference was not statistically significant.

Cramp intensity
(on 3‐point scale; 1=mild; 2=moderate; 3=severe)

The mean cramp intensity in the control groups was
1.04 units

The mean Cramp intensity in the intervention groups was
0.06 lower
(0.17 lower to 0.04 higher)

513
(3 studies)

⊕⊕⊕⊝
moderate1

The difference was not statistically significant.

Participants suffering major adverse events

3 per 1000

9 per 1000
(‐8 to 25)

See comment

513
(3 studies)

⊕⊕⊕⊝
moderate1

Risks were calculated from pooled risk differences. The difference between the two groups was not statistically significant.

Participants suffering minor adverse events

167 per 1000

189 per 1000
(127 to 257)

See comment

483
(2 studies)

⊕⊕⊕⊝
moderate3

Risks were calculated from pooled risk differences. The difference between the two groups was not statistically significant.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1 Only three trials were available for this comparison, two of which were conducted by pharmaceutical investigators on behalf of manufacturers of quinine. A deficiency in the design of one of these trials meant that there was only a two‐day washout between crossover treatments.
2 The effect on cramp number was inconsistent among the three included trials.
3 Only two studies were available for this comparison; one of them having a very short washout period (two days) between treatments.

Figures and Tables -
Summary of findings 2. Quinine versus vitamin E for muscle cramps
Summary of findings 3. Quinine versus a quinine‐vitamin E combination (Q‐Vel) for muscle cramps

Quinine versus a quinine‐vitamin E combination (Q‐Vel) for muscle cramps

Patient or population: patients with muscle cramps
Settings: Outpatients
Intervention: Quinine versus a quinine‐vitamin E combination (Q‐Vel)

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect
(95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Comments

Assumed risk

Corresponding risk

Control

Quinine versus a quinine‐vitamin E combination (Q‐Vel)

Number of cramps over 2 weeks

The mean number of cramps over 2 weeks in the control groups was
8.37

The mean Number of cramps over 2 weeks in the intervention groups was
1.07 higher
(1.08 lower to 3.23 higher)

486
(2 studies)

⊕⊕⊝⊝
low1,2

The difference was not statistically significant.

Cramp intensity
(on 3‐point scale; 1=mild; 2=moderate; 3=severe)

The mean cramp intensity in the control groups was
0.87 units

The mean Cramp intensity in the intervention groups was
0.1 higher
(0.06 lower to 0.26 higher)

510
(3 studies)

⊕⊕⊝⊝
low3,4

The difference was not statistically significant.

Participants suffering major adverse events

8 per 1000

8 per 1000
(‐2 to 18)

See comment

510
(3 studies)

⊕⊕⊕⊝
moderate3

Risks were calculated from pooled risk differences.

Participants suffering minor adverse events

173 per 1000

202 per 1000
(133 to 273)

See comment

510
(3 studies)

⊕⊕⊕⊝
moderate3

Risks were calculated from pooled risk differences. The difference was not statistically significant.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1 The results for cramp number in these two trials were not consistent, each suggesting opposite effects.
2 Only two studies were available for this comparison. Both were conducted by pharmaceutical investigators on behalf of manufacturers of quinine and the quinine‐vitamin E combination.
3 All three trials were conducted by pharmaceutical companies who manufacture quinine and the quinine‐vitamin E combination.
4 There was no consistency between the results for intensity in these 3 trials.

Figures and Tables -
Summary of findings 3. Quinine versus a quinine‐vitamin E combination (Q‐Vel) for muscle cramps
Table 1. Study design of the 23 included trials

Study

Number of participants

Study design

Patient focus

Mean

age (yrs)

Female

Male

F: M ratio

Quinine

dose (mg)

Treatment

period (d)

Washout period (d)

Treatment comparisons

CIBA 1988a

n = 556

Study design = Pb

Patient focus = Ib

45

393

163

2.4

260

14

n/ac

Placebo ✓

Vitamin E ✓

Quinine‐vitamin E combination (Q‐Vel®d)

Leo Winter 1986a

n = 205

Study design = Cb

Patient focus = Ib

44

173

32

5.4

260

5

2

Placebo ✓

Vitamin E ✓

Quinine‐vitamin E combination (Q‐Vel®) ✓

Gorlich 1991

n = 164

Study design = P

Patient focus = I

56

119

45

2.6

260

14

n/a

Placebo ✓

Quinine‐theophylline combination (Limptar®d)✓

Jansen 1997

n = 106

Study design = P

Patient focus = I

51

68

44

1.5

300

14

n/a

Placebo ✓

Diener 2002

n = 94

Study design = P

Patient focus = I

49

66

32

2.1

400

14

n/a

Placebo ✓

Bottner 1984a

n = 69

Study design = C

Patient focus = I

51

66

3

22.0

260

14

14

Placebo ✓

Hays 1986a

n = 62

Study design = C

Patient focus = I

47

49

13

3.8

325

14

14

Placebo ✓

Lee 1991

n = 31

Study design = P

Patient focus = Lb

62

5

26

0.2

400

28

n/a

Placebo ✓

Connolly 1992

n = 30

Study design = C

Patient focus = I

59

0

30

0.0

500

28

28

Placebo ✓

Vitamin E ✓e

Roca 1992

n = 30

Study design = P

Patient focus = Hb

48

10

19

0.5

325

60f

n/a

Vitamin E ✓

Dunn 1993

n = 28

Study design = C

Patient focus = I

67

17

11

1.5

300

30

3

Placebo ✓

Lim 1986

n = 25

Study design = P

Patient focus = I

_

_

_

_

300

≤ 14

n/a

Placebo ✓

BioDesign 1984a

n = 24

Study design = C

Patient focus = I

57

11

13

0.8

260

7

7

Quinine‐vitamin E combination (Q‐Vel®) ✓

Prateepavanich 1999

n = 24

Study design = P

Patient focus = Ig

64

21

3

7.0

300

28

n/a

Xylocaine injection ✓

Warburton 1987

n = 22

Study design = C

Patient focus = I

74

16

6

2.7

300

21

0

Placebo ✓

Jansen 1994

n = 20

Study design = P
Patient focus = I

55

14

6

2.3

300

14

n/a

Placebo ✓

Sidorov 1993

n = 19

Study design = C

Patient focus = I

58

14

2

7.0

200

14

14

Placebo ✓

Smith 1985

n = 21

Study design = C

Patient focus = I

73

_

_

_

300

21

0

Placebo ✓

Maule 1990

n = 16

Study design = C

Patient focus = I

76

10

6

1.7

300

21

0

Placebo ✓

Woodfield 2005

n = 13

Study design = N‐of‐1

Patient focus = I

75

7

6

1.2

200 ‐300

42

0

Placebo ✓

Kaji 1976

n = 9

Study design = C

Patient focus = H

_

_

_

_

320h

42h

0

Placebo ✓

Jones 1983

n = 9

Study design = C

Patient focus = I

_

_

_

_

300

14

14

Placebo ✓

Fung 1989

n = 9

Study design = C

Patient focus = I

63

7

1

7.0

200

28

7

Placebo ✓

aUnpublished.
bC: crossover, P: parallel, H: haemodialysis‐induced cramps, I: idiopathic, L: patients with liver cirrhosis.
cNA: not available.
dQ‐Vel®: trade name for quinine‐vitamin E combination; Limptar®:trade name for quinine‐theophylline combination.
eConnolly 1992 did not directly compare quinine versus vitamin E ‐ using the data provided we were able to draw comparison.
fA 60‐day trial but results only reported from first month of treatment.
gInclusion criteria included presence of myofascial trigger point in gastrocnemius.hQuinine dose given at beginning of each dialysis session (three times per wk) and not daily.

Figures and Tables -
Table 1. Study design of the 23 included trials
Comparison 1. Quinine versus placebo

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Difference in number of cramps over 2 weeks (GIV) ‐ fixed‐effect Show forest plot

14

Cramp number (Fixed, 95% CI)

‐1.81 [‐2.20, ‐1.42]

2 Difference in number of cramps over 2 weeks ‐ random‐effects (minus Connolly 1992) Show forest plot

13

Cramp Number (Random, 95% CI)

‐2.45 [‐3.54, ‐1.36]

3 Difference in number of cramps according to quinine dose (GIV) ‐ fixed‐effect Show forest plot

14

Cramp Number (Fixed, 95% CI)

‐1.81 [‐2.20, ‐1.42]

3.1 500 mg quinine

1

Cramp Number (Fixed, 95% CI)

‐8.7 [‐10.30, ‐7.10]

3.2 400 mg quinine

2

Cramp Number (Fixed, 95% CI)

‐3.36 [‐4.83, ‐1.89]

3.3 300 to 325 mg quinine

5

Cramp Number (Fixed, 95% CI)

‐0.79 [‐1.31, ‐0.26]

3.4 260 mg quinine

3

Cramp Number (Fixed, 95% CI)

‐1.29 [‐2.15, ‐0.42]

3.5 200 mg quinine

3

Cramp Number (Fixed, 95% CI)

‐3.22 [‐4.40, ‐2.04]

4 Difference in cramp intensity (GIV) ‐ fixed‐effect Show forest plot

7

Cramp intensity (Fixed, 95% CI)

‐0.12 [‐0.20, ‐0.05]

5 Change in cramp duration (mins) ‐ random‐effects Show forest plot

2

Change in duration (Random, 95% CI)

‐1.35 [‐4.00, 1.30]

6 Difference in number of cramp days over 2 weeks (GIV) ‐ random‐effects (minus Connolly 1992 Show forest plot

7

Cramp days (Random, 95% CI)

‐1.15 [‐1.93, ‐0.38]

7 Participants suffering minor adverse events ‐ fixed‐effect Show forest plot

16

1447

Risk Difference (M‐H, Fixed, 95% CI)

0.03 [0.00, 0.06]

8 Participants suffering specific minor adverse events Show forest plot

18

Risk Difference (M‐H, Fixed, 95% CI)

Subtotals only

8.1 Gastrointestinal

18

1581

Risk Difference (M‐H, Fixed, 95% CI)

0.03 [0.01, 0.05]

8.2 Headache

18

1581

Risk Difference (M‐H, Fixed, 95% CI)

0.00 [‐0.02, 0.02]

8.3 Tinnitus

18

1581

Risk Difference (M‐H, Fixed, 95% CI)

0.01 [‐0.00, 0.02]

9 Participants suffering major adverse events Show forest plot

18

1613

Risk Difference (M‐H, Fixed, 95% CI)

0.00 [‐0.01, 0.02]

10 Participants suffering specific major adverse events (gastrointestinal) Show forest plot

18

1613

Risk Difference (M‐H, Fixed, 95% CI)

0.01 [‐0.00, 0.02]

Figures and Tables -
Comparison 1. Quinine versus placebo
Comparison 2. Quinine versus vitamin E

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Difference in number of cramps in 2 weeks ‐ random‐effects (minus Connolly 1992) Show forest plot

3

No. cramps (Random, 95% CI)

‐0.24 [‐1.29, 0.81]

2 Difference in cramp intensity ‐ fixed‐effect Show forest plot

3

Cramp intensity (Fixed, 95% CI)

‐0.06 [‐0.17, 0.04]

3 Difference in number of cramp days over 2 weeks ‐ random‐effects (minus Connolly 1992) Show forest plot

2

Cramp days (Random, 95% CI)

‐0.28 [‐0.98, 0.43]

4 Participants suffering minor adverse events ‐ random‐effects Show forest plot

2

688

Risk Difference (M‐H, Random, 95% CI)

0.02 [‐0.04, 0.09]

5 Participants suffering major adverse events ‐ random‐effects Show forest plot

3

748

Risk Difference (M‐H, Random, 95% CI)

0.01 [‐0.01, 0.02]

Figures and Tables -
Comparison 2. Quinine versus vitamin E
Comparison 3. Quinine versus a quinine‐vitamin E combination (Q‐Vel)

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Difference in number of cramps in 2 weeks ‐ random‐effects Show forest plot

2

No. cramps (Random, 95% CI)

1.07 [‐1.08, 3.23]

2 Difference in cramp intensity ‐ random‐effects Show forest plot

3

Cramp intensity (Random, 95% CI)

0.10 [‐0.06, 0.26]

3 Difference in number of cramp days over 2 weeks ‐ random‐effects Show forest plot

2

Cramp days (Random, 95% CI)

0.18 [‐1.13, 1.49]

4 Participants suffering minor adverse events ‐ random‐effects Show forest plot

3

739

Risk Difference (M‐H, Random, 95% CI)

0.03 [‐0.04, 0.10]

5 Participants suffering major adverse events ‐ fixed‐effect Show forest plot

3

739

Risk Difference (M‐H, Fixed, 95% CI)

‐0.00 [‐0.01, 0.01]

Figures and Tables -
Comparison 3. Quinine versus a quinine‐vitamin E combination (Q‐Vel)