Predictive factor for volume reduction of uterine fibroids after short-term use of ulipristal acetate

Ulipristal acetate (UPA) is a selective progesterone receptor modulator, which has been used to treat uterine fibroids. Many published reports about the outcomes indicate effective control of bleeding and reduction in the fibroid volume following both short- and long-term therapy. However, the reported volume reduction varies across different reports. Therefore, the purpose of this study was to investigate the factors that can affect the volume reduction of uterine fibroids, after short-term UPA therapy in patients with symptomatic uterine fibroids. Women treated with UPA for 3 months, between November 2013 and February 2017, for symptomatic uterine fibroids were evaluated retrospectively. The fibroid volume was measured using ultrasonography or magnetic resonance imaging. Response was defined as any reduction in volume after treatment and non-response was defined as no change or increase in volume. Totally, 152 women were treated with UPA and the median volume reduction was 13.1% (interquartile range [IQR] −16.8 to 36.7). Response to treatment was seen in 92 of 152 (60.5%) patients, while 60 women (39.5%) showed no response. Median number of fibroids in the response group was less than that in the non-response group (P = 0.030; median 2, IQR 1–4 vs. median 4, IQR 1–6). On multivariate regression analysis, fewer number of uterine fibroids was an independent factor for predicting a good response to UPA (odds ratio 0.830, CI: 0.710–0.969, P = 0.019). An independent factor that can affect the volume reduction after a 3-month UPA therapy in women with uterine fibroids was the number of fibroids. This indicates that UPA might be ineffective for volume reduction in cases with multiple leiomyomas. However, future prospective studies comparing solitary and multiple leiomyomas for response to UPA are necessary.