Background Premenstrual syndrome (PMS) is a common cause of physical, psychological and social problems in women of reproductive age. The key characteristic of PMS is the timing of symptoms, which occur only during the two weeks leading up to menstruation (the luteal phase of the menstrual cycle). Selective serotonin reuptake inhibitors (SSRIs) are increasingly used as first line therapy for PMS. SSRIs can be taken either in the luteal phase or else continuously (every day). SSRIs are generally considered to be effective for reducing premenstrual symptoms but they can cause adverse effects. Objectives The objective of this review was to evaluate the effectiveness and safety of SSRIs for treating premenstrual syndrome. Search methods Electronic searches for relevant randomised controlled trials (RCTs) were undertaken in the Cochrane Menstrual Disorders and Sub-fertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, PsycINFO, and CINAHL (February 2013). Where insufficient data were presented in a report, attempts were made to contact the original authors for further details. Selection criteria Studies were considered in which women with a prospective diagnosis of PMS, PMDD or late luteal phase dysphoric disorder (LPDD) were randomised to receive SSRIs or placebo for the treatment of premenstrual syndrome. Data collection and analysis Two review authors independently selected the studies, assessed eligible studies for risk of bias, and extracted data on premenstrual symptoms and adverse effects. Studies were pooled using random-effects models. Standardised mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for premenstrual symptom scores, using separate analyses for different types of continuous data (that is end scores and change scores). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for dichotomous outcomes. Analyses were stratified by type of drug administration (luteal or continuous) and by drug dose (low, medium, or high). We calculated the number of women who would need to be taking a moderate dose of SSRI in order to cause one additional adverse event (number needed to harm: NNH). The overall quality of the evidence for the main findings was assessed using the GRADE working group methods. Main results Thirty-one RCTs were included in the review. They compared fluoxetine, paroxetine, sertraline, escitalopram and citalopram versus placebo. SSRIs reduced overall self-rated symptoms significantly more effectively than placebo. The effect size was moderate when studies reporting end scores were pooled (for moderate dose SSRIs: SMD -0.65, 95% CI -0.46 to -0.84, nine studies, 1276 women; moderate heterogeneity (I-2 = 58%), low quality evidence). The effect size was small when studies reporting change scores were pooled (formoderate dose SSRIs: SMD-0.36, 95% CI -0.20 to -0.51, four studies, 657 women; low heterogeneity (I-2=29%), moderate quality evidence). SSRIs were effective for symptom relief whether taken only in the luteal phase or continuously, with no clear evidence of a difference in effectiveness between these modes of administration. However, few studies directly compared luteal and continuous regimens and more evidence is needed on this question. Withdrawals due to adverse effects were significantly more likely to occur in the SSRI group (moderate dose: OR 2.55, 95% CI 1.84 to 3.53, 15 studies, 2447 women; no heterogeneity (I-2 = 0%), moderate quality evidence). The most common side effects associated with a moderate dose of SSRIs were nausea (NNH = 7), asthenia or decreased energy (NNH = 9), somnolence (NNH = 13), fatigue (NNH = 14), decreased libido (NNH = 14) and sweating (NNH = 14). In secondary analyses, SSRIs were effective for treating specific types of symptoms (that is psychological, physical and functional symptoms, and irritability). Adverse effects were dose-related. The overall quality of the evidence was low to moderate, the main weakness in the included studies being poor reporting of methods. Heterogeneity was low or absent for most outcomes, though (as noted above) there was moderate heterogeneity for one of the primary analyses. Authors' conclusions SSRIs are effective in reducing the symptoms of PMS, whether taken in the luteal phase only or continuously. Adverse effects are relatively frequent, the most common being nausea and asthenia. Adverse effects are dose-dependent.
