Dahle 1995.
| Study characteristics | ||
| Methods | Double‐blind, parallel‐group RCT | |
| Participants | 73 pregnant women (mean 29 wk gestation) with rest cramps and no previous cramp treatment. Recruitment from Swedish prenatal care clinics | |
| Interventions | Either a chewable tablet containing 122 mg elemental magnesium ("primarily as Mg lactate or Mg citrate") (n = 34), or matched placebo tablet (n = 35), taken once each morning and twice each evening for 3 weeks | |
| Outcomes | Primary outcome unclear Change in cramp frequency on a 5‐point ordinal scale Time of day cramps occurred on a 4‐point nominal scale Presence of symptoms the day after a night of cramping on a 3‐point ordinal scale Global participant assessment of treatment effect on a 5‐point ordinal scale Cramp intensity on a VAS Serum magnesium and calcium and 24‐hour urinary magnesium and calcium excretion |
|
| Conflicts of interest | No mention of conflicts of interest | |
| Funding | Manufacturer sponsored | |
| Notes | Published. Laboratory tests performed at only 1 of the 2 centres. The period during which the trial was conducted is not stated (first received by publisher 2 August 1994). | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "The patients were then randomly allocated to either magnesium or placebo". No further description |
| Allocation concealment (selection bias) | Unclear risk | Not described |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Quote: “A magnesium‐placebo tablet batch of 90 numbered bottles was prepared by ACO Lakemedel...” Comment: probably satisfactory, although pills were not described |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Outcomes measured via an interview. No information available regarding blinding of interviewers but study mentions double‐blinding |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | 4/73 participants dropped out of the study and were excluded from the analysis. Reasons for dropout were well described but treatment group was not identified. 1 placebo participant withdrew from treatment but appears (unclear) to have been included in the analysis. Comment: probably adequate as total number of dropouts was small |
| Selective reporting (reporting bias) | High risk | No description of outcomes by primary and secondary, and outcomes were incompletely described in methods, i.e. only in the results is it evident that before and after comparisons, mean differences and numbers attaining specific cut‐offs are used. Unclear how well outcomes were predefined. Inadequate reporting: no actual numbers for many P values. This study also reported a reduction in cramp frequency "from the initial average of every other day, to every 3 days in the placebo group and one to two times a week in the magnesium group (P < 0.05)". However, "every 3 days" and "one to two times a week" do not belong to the 5‐point ordinal scale used to measure this outcome (daily, every other day, twice a week, once a week, never) |
| Cramp diary (recall bias) | High risk | No diary used |
| Other bias | Low risk | Participants treated differently at each site (1 used laboratory testing, the other did not). Likely not an important difference |