Oral continuous combined 0.5 mg estradiol valerate and 5 mg dydrogesterone as daily add-back therapy during post-operative GnRH agonist treatment for endometriosis in Chinese women.

OBJECTIVE: To evaluate the lowest effective dose of combined estrogen and progestogen (E(2)+P) add-back therapy during post-operative gonadotropin-releasing hormone agonist (GnRHa) treatment for endometriosis in Chinese women.

STUDY DESIGN: The study enrolled 81 patients aged 18 to 50 years with stage III or IV endometriosis, as diagnosed by surgery. All patients were given GnRHa 3.6 mg by subcutaneous injection once every 28 days for a total of three times. Patients were divided into three groups: the first (n = 35; GnRHa only group) received GnRHa only without add-back therapy, the second (n = 35; 0.5 mg E(2)+P add-back group) received GnRHa plus 0.5 mg estradiol valerate and 5 mg dydrogesterone orally every day, and the third (n = 11; 1 mg E(2)+P add-back group) received GnRHa plus 1 mg estradiol valerate and 10 mg dydrogesterone orally every day for the duration of treatment. All patients were required to follow up at our hospital at 4, 8 and 12 weeks after treatment initiation to assess efficacy and levels of serum reproductive hormones.

RESULTS: Compared with baseline levels, serum levels of the four reproductive hormones assessed (E(2), LH, P(4) and FSH) were significantly decreased in both the GnRHa only and the 0.5 mg E(2)+P add-back groups at 4, 8, and 12 weeks after treatment; and levels reached a stable state at 4 weeks of treatment. In the 1 mg E(2)+P add-back group, LH and FSH serum levels were significantly decreased, while those of E(2) and P were not significantly different at any of the time points assessed. In the 0.5 mg E(2)+P add-back group, E(2) serum levels decreased drastically at first, then gradually over the course of the study. In contrast, pre- and post-treatment E(2) serum levels in the 1 mg E(2)+P add-back group were not significantly different, and these levels were over 45 pg/mL for the entire study duration. Comparison among groups showed that E(2) levels in both add-back groups were significantly higher than in the GnRHa only group at 12 weeks after treatment. Furthermore, E(2) serum levels in the two add-back groups at 8 and 12 weeks after treatment were significantly different.

CONCLUSION: Oral continuous combined 0.5 mg/d estradiol valerate and 5 mg/d dydrogesterone as immediate add-back therapy during post-operative GnRH agonist treatment for severe endometriosis may be the most suitable regimen for Chinese women.