Nonsteroidal anti-inflammatory drugs for dysmenorrhoea

Dysmenorrhoea is a common gynaecological problem consisting of painful cramps accompanying menstruation, which in the absence of any underlying abnormality is known as primary dysmenorrhoea. Research has shown that women with dysmenorrhoea have high levels of prostaglandins, hormones known to cause cramping abdominal pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) are drugs which act by blocking prostaglandin production.

The purpose of this review is to compare nonsteroidal anti-inflammatory drugs used in the treatment of primary dysmenorrhoea versus placebo, versus paracetamol and versus each other, to evaluate their effectiveness and safety.

We searched the following databases to May 2009: Cochrane Menstrual Disorders and Subfertility Group trials register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and Web of Science. The National Research Register and the Clinical Trials Register were also searched. Abstracts of major scientific meetings and the reference lists of relevant articles were checked.

All randomised controlled comparisons of NSAIDs versus placebo, other NSAIDs or paracetamol, when used to treat primary dysmenorrhoea.

Two reviewers independently assessed trials for quality and extracted data, calculating odds ratios (ORs) for dichotomous outcomes and mean differences for continuous outcomes, with 95% confidence intervals (CIs). Inverse variance methods were used to combine data.

Seventy-three randomised controlled trials were included. Among women with primary dysmenorrhoea, NSAIDs were significantly more effective for pain relief than placebo (OR 4.50, 95% CI: 3.85, 5.27). There was substantial heterogeneity for this finding (I(2) statistic =53%): exclusion of two outlying studies with no or negligible placebo effect reduced heterogeneity, resulting in an odds ratio of 4.14 (95% CI: 3.52, 4.86, I(2)=40%). NSAIDs were also significantly more effective for pain relief than paracetamol (OR 1.90, 95% CI:1.05 to 3.44). However, NSAIDS were associated with significantly more overall adverse effects than placebo (OR 1.37, 95% CI: 1.12 to 1.66). When NSAIDs were compared with each other there was little evidence of the superiority of any individual NSAID for either pain-relief or safety. However the available evidence had little power to detect such differences, as most individual comparisons were based on very few small trials.

NSAIDs are an effective treatment for dysmenorrhoea, though women using them need to be aware of the significant risk of adverse effects. There is insufficient evidence to determine which (if any) individual NSAID is the safest and most effective for the treatment of dysmenorrhoea.