Long-Term Danazol Therapy in Autoimmune Thrombocytopenia: Unmaintained Remission and Age-Dependent Response in Women

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Abstract
Study Objective: To assess the long-term benefit and side effects of danazol therapy, and to delineate factors influencing the responses in patients with autoimmune thrombocytopenia. Design: Before and after trial. Setting: Referral-based hematology clinics and the University of Miami teaching hospitals. Patients: Data were collected on 96 patients (60 women and 36 men, 45 of whom had had splenectomies) receiving danazol therapy for autoimmune thrombocytopenia and analyzed. Intervention: Danazol was added to the previous therapy or begun as an initial therapy. Glucocorticoids were tapered gradually. Measurements and Main Results: The overall response rate to danazol was 61.4%. Among responders, the platelet counts (mean ± SD) before and after danazol treatment were 36 ± 24 x 109/L and 145 ± 77 x 109/L, respectively, and the time to response was 2.7 ± 3 months. Sex, age, and the status of the spleen (absent or present) influenced the responses to danazol: In women, but not in men, response rates improved with advancing age, especially in the nonsplenectomized women. This may be because estrogen levels are high in younger women and low in older women and men. Danazol, when given longer than a year, induced remissions lasting for years even after its discontinuation, but early relapses were frequent when danazol was administered for less than 6 months. Platelet-associated IgG returned to normal range during unmaintained remission. Conclusion: Danazol is best suited for long-term medical management of autoimmune thrombocytopenia. It is well tolerated, and lasting, unmaintained remissions often occur after prolonged danazol administration. Age, sex, and the status of the spleen influence the responses. When danazol therapy is used, glucocorticoids can be substantially reduced in dosage or withdrawn. Danazol is a good alternative to splenectomy in elderly persons, especially in women.