Nafarelin for endometriosis: a large-scale, danazol-controlled trial of efficacy and safety, with 1-year follow-up. The Nafarelin European Endometriosis Trial Group (NEET).

OBJECTIVE: To compare the efficacy and safety of nafarelin and danazol for endometriosis. DESIGN: Randomized, double-blind, double-dummy. SETTING: Multiple European institutions. PATIENTS: In total, 307 patients with laparoscopically diagnosed endometriosis received nafarelin (n = 206) or danazol (n = 101); 263 (171 nafarelin, 92 danazol) were analyzed for efficacy. INTERVENTIONS: Intranasal nafarelin 200 micrograms two times a day or oral danazol 200 mg three times a day were administered for 6 months. MAIN OUTCOME MEASURES: Efficacy assessments were based on preadmission and end-of-treatment laparoscopic scores and subjective symptom scores at admission, end of treatment, 1, 3, 6, and 12 months after treatment. Safety was evaluated by adverse events and clinical laboratory tests. RESULTS: In each group, endometriosis growth and symptoms significantly improved during treatment (P less than 0.001). After treatment, symptoms returned in each group, but severity was less than at admission at all time points (P less than or equal to 0.016). Mean body weight increased in the danazol-treated group (P less than 0.001), serum glutamic oxaloacetic transaminase increased in both groups (P less than 0.001 for both) but significantly more in danazol users (P less than 0.002), and more nafarelin recipients had hot flushes (P less than 0.001). CONCLUSIONS: Nafarelin and danazol were equally effective in reducing endometriosis growth and symptoms during treatment and in preventing the return of symptoms during 12-month follow-up.