Kaji 1976.
| Methods | Double‐blind RCT of cross‐over design, set in New York, USA | |
| Participants | 9 participants with chronic renal failure on maintenance haemodialysis 3 times per week, and with frequent muscle cramps | |
| Interventions | Participants given quinine sulphate 320 mg or placebo at the beginning of each dialysis treatment, for a period of 12 weeks | |
| Outcomes | Cramp frequency, cramp intensity (graded mild = cramp lasting < 5 minutes and disappeared spontaneously, moderate = cramp lasting between 5 and 10 minutes and ceased after reduction of dialysis pump‐rate and severe = cramp lasting > 15 minutes and unrelieved despite reduction in pump rate), cramp duration, adverse events | |
| Notes | Study conducted in New York. Frequency of muscle cramps expressed as number of dialyses affected by cramps, rather than number or cramps during a fixed period | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "...a randomised double blind cross‐over trial..." Comment: details of randomisation not provided |
| Allocation concealment (selection bias) | Unclear risk | No details regarding methods of concealment are provided |
| Blinding (performance bias and detection bias) All outcomes | Low risk | Quote: "Quinine sulphate and placebo were placed in identical gelatin capsules and delivered from the hospital pharmacy...The pharmacy kept a record of the content of the capsule...but this information was withheld from the dialysis staff..." Comment: adequately blinded |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | All participants completed the trial |
| Selective reporting (reporting bias) | High risk | The distribution and timing of cramps, and the blood pressure and dialysis pump rate during an episode were said to be outcomes but these are not mentioned in the Results/Discussion sections |
| Other bias | High risk | Only cramps during dialysis sessions were assessed; effect of treatment on cramps outside of dialysis sessions was not measured. Also, there was no washout period between cross‐over treatments |