Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Absence from work/school
Systematic review	24 women with primary dysmenorrhoea Data from 1 RCT	Mean hours of absence from work or school 1.23 hours with low-frequency TENS 1.42 hours with placebo TENS or tablet	WMD –0.2 hours 95% CI –0.6 hours to +0.2 hours Randomisation and blinding unclear		Not significant