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. 2020 Sep 21;2020(9):CD009402. doi: 10.1002/14651858.CD009402.pub3

Sohrabvand 2006.

Study characteristics
Methods Open‐label RCT with 4 parallel treatment groups
Participants 84 pregnant women. Recruitment method (Iranian women) not provided
Interventions Group 1: 500 mg calcium carbonate tablet once daily (n = 21)
Group 2: 7.5 mmol magnesium aspartate (182 mg elemental magnesium) twice daily (n = 21)
Group 3: 100 mg of thiamine (vitamin B₁) plus 40 mg of pyridoxine (vitamin B₆) once daily (n = 21)
Group 4: no treatment (n = 21)
Outcomes "Change in muscle spasms" on a 3‐point ordinal scale (no change, "relative improvement", or "absolute improvement")
Conflicts of interest Funding source and conflicts of interest not provided
Funding Funding source and conflicts of interest not provided
Notes Unusual design. Each treatment was given over 2 weeks but efficacy was assessed at 4 weeks. Published as a "brief communication" (letter) only. No definition of relative and absolute improvement was given in the manuscript but this was confirmed with the author to mean partial and complete resolution of the overall cramp burden (which presumably takes into account both intensity and frequency). The period during which the trial was conducted is not stated (first received by publisher 6 March 2006)
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Unclear risk No description. Baseline characteristics were said to be not significantly different but they were not provided
Allocation concealment (selection bias) Unclear risk No description. Baseline characteristics were said to be not significantly different but they were not provided
Blinding of participants and personnel (performance bias)
All outcomes High risk Open‐label trial. Unclear who rated the degree of improvement (participant or physician)
Blinding of outcome assessment (detection bias)
All outcomes High risk Open‐label trial. Unclear who rated the degree of improvement (participant or physician)
Incomplete outcome data (attrition bias)
All outcomes Low risk No details in the manuscript regarding flow of participants but author communication suggests no dropouts
Selective reporting (reporting bias) Unclear risk Primary outcome not identified (though only 1 outcome reported)
Table 2 showed statistical significance in total improvement for groups 2 and 3 compared to group 4 but in the text it stated groups 1 and 3 (which is supported by the CI results). Trial was very under‐reported. Outcomes were grouped in an impractical way
Cramp diary (recall bias) High risk Specifics were not given but there appeared to have only been a qualitative assessment of the change in cramps upon study completion
Other bias Low risk No obvious other bias