Jansen 1994.
| Methods | Double‐blind, parallel group RCT, set in the Netherlands. | |
| Participants | 20 adult volunteers (median age 55 years) from general population who suffered at least 3 muscle cramps per week | |
| Interventions | Hydroquinine hydrobromide 300 mg daily (200 mg at supper, 100 mg at bedtime) or placebo for 2 weeks. This was followed by a 2‐week intervention‐free period whereby persistence of drug effect was monitored | |
| Outcomes | Reduction in cramp number from baseline for each treatment group. Cramp severity (scale not stated), cramp duration, cramp location and adverse events were also outcomes | |
| Notes | Adult volunteers were recruited via a notice in a regional newspaper, with a "small financial reward". Randomisation led to quinine group being solely women whilst all men were randomised into placebo group | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "Twenty participants were randomly allocated to receive either active drug or placebo." Comment: no details of the randomisation process are provided |
| Allocation concealment (selection bias) | Low risk | Quote: "During the trial only the manufacturer knew the codes disclosing drug and placebo." Comment: probably adequate |
| Blinding (performance bias and detection bias) All outcomes | High risk | Quote: "...three quinine users who complained of a bitter taste possibly were not blind to the type of medication..." Comment: inadequate blinding with high risk of bias |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | One participant dropped out of the placebo group but it is unclear if an intention‐to‐treat analysis was performed |
| Selective reporting (reporting bias) | High risk | Quote: "Differences in severity, duration and location ... between placebo...and drug treatment were small." Comment: emphasis placed on cramp number, with no mention of the results for the 3 other outcomes |
| Other bias | Unclear risk | Volunteers were recruited via notice in a regional newspaper, for a "small financial reward". The quinine group was solely women, whilst all men were randomised into placebo group |