We trained a nurse from each participating practice. In the first six practices to participate, patients thought to be eligible were sent an information sheet and an invitation to participate in the study. Following a lower than expected response rate we agreed a modification to the recruitment procedure with the ethics committees. In a further 24 practices, patients were invited by letter to express an interest and those responding were then telephoned by the practice nurse, who checked eligibility and sent an information sheet and appointment to those still wishing to participate. Patients then attended an interview at their practice during which the nurse obtained written consent and completed a questionnaire to record baseline data.
How this fits in
Quinine is commonly used as a treatment for night cramps but there are doubts about its effectiveness and it has potential side effects. In 1979 Daniell reported the effectiveness of regular calf-stretching exercises in preventing night cramps but his findings have never been confirmed by a robust study. This randomised study suggests that calf-stretching exercises have no benefit in night cramps but that a significant number of those on repeat prescriptions for quinine may be able to stop medication without major problems.
Randomisation to the trial took place when the nurse opened a sealed, numbered, opaque envelope containing intervention instructions that had been previously randomised by the research assistant using random number tables. Patients were then shown how to complete a 6-week diary record and given advice to either continue or discontinue taking quinine tablets and to undertake a daily programme of either stretching or placebo exercises for which they received training. The placebo exercise was devised to be of comparable duration and simplicity to the intervention stretching exercise, but was passive and involved negligible stretching of the muscles of the calf and foot (Supplementary Box 1). We sought to minimise intervention contamination by terming the stretching and placebo exercises as ‘standing’ and ‘lying’ exercises, respectively. Patients were told that at the end of 6 weeks they could continue the exercises if they wished and also decide themselves whether or not to continue or resume taking quinine tablets. They were also given an instruction sheet describing the exercise programme and confirming the advice.
One week later the nurse telephoned the patient to check that they were coping with the diary recording. Intervention advice was not repeated. Twelve weeks after the interview, patients were sent a self-completion postal questionnaire. Non-responders were telephoned to record their questionnaire responses. Twelve weeks was considered to be an appropriate interval at which to measure the main outcomes as it captured the considered response of patients to the choice resulting from the intervention advice. To avoid bias, intervention codes from the data sheets were removed prior to data entry and then recombined for analysis.
