Objectives: To study the dropout rate for use of sildenafil after initial prescription and during successful treatment to clarify their risk factors.
Methods: A total of 1036 patients with erectile dysfunction who were treated with sildenafil were analyzed. The dropout rate during successful treatment and its risk factors were assessed using the Kaplan–Meier method and Cox proportional hazards model, respectively.
Results: Thirty-one percent (n = 322) of the patients dropped out after the initial prescription. The cumulative dropout rate during successful treatment at 3 years after starting usage was 48%. A lower International Index of Erectile Function (IIEF-5) score before treatment was a significant risk factor for dropout during a successful treatment course (P < 0.029 by the Cox proportional hazards model).
Conclusions: Approximately 30% and 50% of the patients dropped out of treatment after the first prescription and at 3-year follow-up, respectively. Adequate initial instruction and long-term follow-up are required even for patients with successful treatment.