Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Leg cramp symptoms
Systematic review	People with nocturnal leg cramps 7 RCTs in this analysis	Reduction in frequency of nocturnal leg cramps 4 weeks with quinine with placebo Absolute results reported graphically	ARR for quinine v placebo 3.60 cramps/month 95% CI 2.15 to 5.05 cramps/month RR 0.21 95% CI 0.12 to 0.30	Moderate effect size	quinine
Systematic review	People with cramps 14 RCTs in this analysis	Difference in number of cramps (occurring day or night) 2-week treatment period with quinine with placebo	Mean difference in the number of cramps –1.81 95% CI –1.42 to –2.20 P <0.00001 Significant heterogeneity in analysis (I2 = 89%; P value for heterogeneity <0.0001) See Further information on studies	Effect size not calculated	quinine
Systematic review	People with cramps 7 RCTs in this analysis	Difference in cramp intensity (measured on a 3-point scale where 1 = mild pain; 2 = moderate pain; 3 = severe pain) with quinine with placebo	Cramp intensity –0.12 95% CI –0.20 to –0.05 P = 0.0011	Effect size not calculated	quinine
Systematic review	People with leg cramps 2 RCTs in this analysis	Change in cramp duration (minutes) with quinine with placebo	Change in duration –1.35 minutes 95% CI –4.00 to +1.30 minutes P = 0.32 The review reported that of 6 further RCTs that did not present data in a form that allowed them to be added to the meta-analysis, 5 found no significant difference with regard to cramp duration		Not significant
Systematic review	People with cramps 7 RCTs in this analysis	Difference in number of cramp days 2 weeks with quinine with placebo	Cramp days –1.15 95% CI –1.93 to –0.38 P = 0.0036 Significant heterogeneity in analysis (I2 = 86%; P <0.00001); this was following the exclusion of 1 RCT which was causing heterogeneity; further sensitivity analysis not reported	Effect size not calculated	quinine