Woodfield 2005.

Methods	Double‐blind, randomised controlled 'N‐of‐1' trial, set in New Zealand
Participants	13 elderly participants (median age 75 years), suffering at least 2 cramps per week
Interventions	2‐week washout period followed by 3 x 4‐week treatment blocks in which participants are randomised to either placebo or quinine sulphate (200 to 300 mg) for 2 weeks and then the other treatment for 2 weeks
Outcomes	Cramp number, cramp days
Notes	General practices in New Zealand
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Patients were randomly assigned to one of eight possible treatment sequences..."; "...copy of the randomisations code..." Comment: probably done as description suggests centrally‐organised randomisation codes
Allocation concealment (selection bias)	Low risk	Quote: "A sealed copy of the randomisation code..."; " A master copy of the randomisation codes was also held by the research supervisor..." Comment: probably done
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "Both the patients and the researcher interacting with them and conducting the analyses were blinded..." Comment: adequate double‐blinding
Incomplete outcome data (attrition bias) All outcomes	Low risk	Full explanation provided for the 3 drop‐outs
Selective reporting (reporting bias)	Low risk	All outcomes measured that were described in the initial protocol were addressed in the analysis
Other bias	Unclear risk	Participants continued with their most recent dose of quinine, thus this varied between participants

RCT: randomised controlled trial