Long-term treatment for endometriosis with dienogest: efficacy, side effects and tolerability

Dienogest (DNG) improves endometriosis-associated pain (EAP) and patients' quality of life; however, the modern cornerstone of the management of endometriosis is the long-term adherence of the patient to medical treatment.

To evaluate DNG as a long-term treatment of endometriosis, focusing on patients' compliance and side effects, also correlating with different phenotypes of endometriosis.

This was a cohort study on a group of patients with endometriosis (n = 114) undergoing long-term treatment with DNG. During the follow up visits (12, 24, and 36 months) patients were interviewed: an assessment of EAP was performed by using a visual analogue scale (VAS) and side effects were evaluated by using a specific questionnaire of 15 items.

At 12 months, 81% were continuing the DNG treatment, with a significant reduction of dysmenorrhea, dyspareunia, dyschezia, dysuria and chronic pelvic pain. Of the 19% that discontinued the treatment: 62% was due to spotting, reduced sexual drive, vaginal dryness, and mood disorders. The improvement of EAP was significant for all endometriosis phenotypes, especially in patients with the deep infiltrating type. At 36 months, 73% of patients were continuing the treatment, showing a significant reduction of EAP through the follow up, along with an increase of amenorrhea (from 77% at 12 months to 93% at 36 months). In a subgroup of 18 patients with gastrointestinal disorders, DNG was administered vaginally at the same dosage, showing similar results in terms of efficacy and tolerability.

DNG was an effective long-term treatment for all endometriosis phenotypes, with few side effects that caused the discontinuation of the treatment mainly during the first year. Thus, the course of 1-year treatment is a predictive indicator for long-term treatment adherence.