Summary of findings 2. Quinine versus vitamin E for muscle cramps.
| Quinine versus vitamin E for muscle cramps | ||||||
| Patient or population: people 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 | |||||
| Vitamin E | Quinine | |||||
| 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 2 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 2 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% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval | ||||||
| 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. | ||||||
1Only 3 trials were available for this comparison, 2 of which were conducted by pharmaceutical investigators on behalf of manufacturers of quinine. A deficiency in the design of 1 of these trials meant that there was only a 2‐day washout between cross‐over treatments. 2The effect on cramp number was inconsistent among the 3 included trials. 3Only 2 studies were available for this comparison; 1 of them having a very short washout period (2 days) between treatments.