A digital self-care intervention for psychological distress associated with premenstrual syndrome: a fully online controlled trial using alternating allocation

Abstract Background Premenstrual syndrome (PMS) is associated with significant psychological distress and productivity loss in women. This study aimed to evaluate whether a low-intensity digital intervention—comprising a symptom-tracking smartphone application and standardized informational emails—could reduce the psychological burden of PMS among women who self-identified as experiencing PMS. Methods We conducted a fully internet-based, open-label, parallel-group, nonrandomized controlled trial using centrally administered alternating allocation among women aged 18 years or older in Japan who self-identified as experiencing PMS. Participants were allocated alternately to either a 3-month intervention group (daily symptom tracking using a smartphone app and twice-weekly informational emails) or a waitlist control group. The primary outcome was the between-group difference in change scores on the psychological subscale of the Japanese version of the PMS-Impact Scale, measured from baseline to 3 months. Analyses were conducted per protocol. Results A total of 419 women were enrolled and assigned to either the intervention group (n = 210) or the waitlist control group ( n = 209). Of these, 355 participants were included in the per-protocol analysis. The intervention group showed greater improvement in self-reported psychological distress than the waitlist control group. The between-group difference in change score, defined as intervention minus control, was − 1.37 points (95% CI, − 2.47 to − 0.27; p = 0.015). Conclusions A simple, scalable digital intervention was associated with greater improvement in self-reported psychological distress among women who self-identified as experiencing PMS. These findings suggest that accessible, non–clinician-led tools may have potential as a self-management strategy for PMS, although causal interpretation is limited by the nonrandomized design. Trial registration This trial was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) on September 26, 2022. Trial registration number: UMIN000048422.