Roguin Maor 2017.

Study characteristics
Methods	Parallel, double‐blind, randomized, placebo‐controlled trial
Participants	94 non‐pregnant nocturnal leg cramps sufferers at least 21 years of age (mean age 64.9 years, 39% male) with normal renal function and having at least 4 nocturnal leg cramps during the 2‐week screening phase. Recruitment via advertisements in clinics, pharmacies and local media in northern Israel
Interventions	Either 1 capsule of 865 mg magnesium oxide (n = 48) (520 mg elemental Mg) once daily at bedtime or a matching placebo (n = 46) for 4 weeks. All participants received daily text reminders and twice weekly phone calls to ensure adherence to allocation and completion of diaries.
Outcomes	Primary: change in the frequency of nocturnal leg cramps per week between the 4‐week treatment phase and the 2‐week screening phase, as recorded in a sleep diary Secondary: Change in cramps severity (each cramp rated 0 to 10 from least painful to most painful) Cramps duration (measured in minutes) Quality of life (measured via the Short‐Form 36 Health Survey (SF‐36) questionnaire at enrolment and within 1 week after treatment) Quality of sleep (measured via the Pittsburg Sleep Quality Index at enrolment and within 1 week after treatment)
Conflicts of interest	Authors reported no conflict of interest
Funding	The study was funded entirely by the manufacturer (Naveh‐Pharma Ltd)
Notes	Published. Stopped early for futility at an interim analysis. Trial conducted from February to October 2013
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A randomization schedule was computer generated using blocks of 10 and participants received sequential numbers. Number of cramps per week at baseline was somewhat imbalanced (7.84 cramps per week in the Mg group, 8.51 cramps per week in the placebo group). This is likely to bias our outcome of difference between groups in cramps per week on treatment in favour of the Mg group, whose baseline rate was lower
Allocation concealment (selection bias)	Low risk	Identical pills and bottles were prepared in advance. These bottles were identified with sequential numbers that were assigned to each participant in order of recruitment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Identical capsules and bottles. "Both patients and researchers were blind to treatment allocation"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcomes reported (in diaries) by blinded participants
Incomplete outcome data (attrition bias) All outcomes	Low risk	All analyses were ITT with multiple imputations of missing data (assumed to be the baseline value). 3/46 (6.5%) placebo and 3/48 (6.3%) magnesium recipients discontinued the intervention
Selective reporting (reporting bias)	Low risk	Results are reported for all outcomes described under methods and these match the trial protocol
Cramp diary (recall bias)	Low risk	Diary used
Other bias	Low risk	No obvious other bias