Frusso 1999.
Methods | Double‐blind RCT of cross‐over design | |
Participants | 45 non‐pregnant rest cramp sufferers > 18 years (mean age 61.6 years) having a normal neurologic exam and at least 6 leg cramps in a 4‐week placebo run‐in. Recruitment from a single large university‐based Argentinean family practice clinic. | |
Interventions | Magnesium citrate 900 mg pill (approx. 100 mg elemental magnesium) twice daily or similar tasting and appearing placebo, each for 4 weeks. Four‐week placebo run‐in and 4‐week washout between treatments. | |
Outcomes | Primary: Number of cramps in treatment period. Secondary: Cramp duration by 4 ordinal categories (< 5 minutes, 5 to 10 minutes, 10 to 30 minutes, > 30 minutes). Cramp intensity by “analog scale”. Sleep disturbance on a 0 to 10 scale with 0 = “no sleep disturbance” and 10 = “could not sleep because of the cramps”. Adverse events. | |
Notes | Published. Independent funding. The 4‐week placebo run‐in was pre‐randomization. Unclear what the range for the analog scale of intensity is (assumed 0 to 10). Cramp duration was recorded by ordinal category but reported with a mean and standard deviation in minutes. | |
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Unclear risk | Quote: “Patients randomly received magnesium or placebo...” Comment: unclear how randomization was performed |
Allocation concealment (selection bias) | Unclear risk | Quote: “The codes were inside a sealed envelope opened at the end of the analysis.” Comment: Unclear who allocated subjects and maintained the blinding |
Blinding (performance bias and detection bias) All outcomes | Low risk | Quote: “Each pill contained 900 mg of magnesium citrate or matched placebo (same appearance and taste).” Comment: Satisfactory blinding |
Incomplete outcome data (attrition bias) All outcomes | Low risk | 3/45 subjects withdrew with reasons given. It is not stated which intervention they were receiving at the time or how their data were dealt with. Comment: Probably satisfactory as the number of dropouts was small. |
Selective reporting (reporting bias) | Unclear risk | No indication of selective reporting for clinical endpoints (although urine for magnesium was collected and not reported). Duration of cramps was measured on a 4‐point ordinal scale but results were reported with the mean duration and standard deviation measured in minutes as though they were a continuous variable |
Cramp diary (recall bias) | Low risk | Diary used |
Other bias | Low risk | No obvious other bias |