The quality of evidence is downgraded by study quality, indirectness of the evidense, and imprecise results.
A network meta-analysis «de Wit AE, de Vries YA, de Boer MK et al. Efficacy of combined oral contraceptives for depressive symptoms and overall symptomatology in premenstrual syndrome: pairwise and network meta-analysis of ra»1 included 9 studies with a total of 1205 subjects. Combined oral contraceptives (COC) were more efficacious than placebo in treating overall premenstrual symptomatology (standardized mean difference, 0.41; 95% credible interval, 0.17 to 0.67), but not premenstrual depressive symptoms specifically (standardized mean difference, 0.22; 95% credible interval, -0.06 to 0.47). There was no evidence for one COC being more efficacious than any other.
A Cochrane review «Oral contraceptives containing drospirenone for premenstrual syndrome»1 «Ma S, Song SJ. Oral contraceptives containing drospirenone for premenstrual syndrome. Cochrane Database Syst Rev 2023;6(6):CD006586. »2 included 5 trials with a total of 858 women. Drospirenone plus ethinyl estradiol 20μg improved overall premenstrual symptoms (standardised mean difference (SMD) -0.41, 95% CI -0.59 to -0.24; 2 RCTs, n=514; I²=64%); productivity (WMD -0.31; 95% CI -0.55 to -0.08), social activities (WMD --0.29; 95% CI -0.54 to -0.04), and relationships (WMD -0.30; 95% CI -0.54 to -0.06). Side effects more common with COC use were nausea, intermenstrual bleeding, and breast pain.