An Empirical vs Risk-Based Approach Algorithm to Intracavernosal Injection Therapy: A Prospective Study

Introduction Intracavernosal injection (ICI) therapy is widely used for the treatment of erectile dysfunction (ED). Its use in practice is largely empirical and has not been validated with evidence-based approaches. Aim To compare two strategies for ICI, specifically a risk-based approach and an empiric-based approach, and assess the efficacy, patient satisfaction, and complication rates of the two treatment approaches. Methods After obtaining approval from the institutional review board, a prospective database of patients enrolled in the ICI program at the Johns Hopkins Hospital (Baltimore, MD, USA) from May 2012 through May 2014 was amassed. Demographic information, treatment outcomes, and subjective patient evaluations of sexual function (International Index of Erectile Function erectile function domain [IIEF-EF], Quality of Erection Questionnaire [QEQ], Sexual Quality of Life [SQoL], and Erectile Dysfunction Inventory of Treatment Satisfaction [EDITS]) were obtained at baseline and at 3 and 6 months. Two approaches were compared. Group 1 received empiric ICI treatment initially with prostaglandin E₁ (PGE1) 10 μg irrespective of ED etiology or severity. After initial dosing with PGE1 in the clinic, adjustments were made to titrate or change formulations pending on patient results. Group 2 received a risk-based approach, in which an algorithm that factored in ED etiology and number of ED risk factors was used for a bimix (papaverine 30 mg/mL, phentolamine 1 mg/mL), a low-dose trimix (papaverine 30 mg/mL, phentolamine 1 mg/mL, PGE1 10 μg/mL), or a high-dose trimix (papaverine 30 mg/mL, phentolamine 2 mg/mL, PGE1 40 μg/mL). Dose titration was permitted in the two groups. Statistical analysis was carried out using t-test and χ² analysis. Main Outcome Measures The study design was powered for a non-inferiority comparison of the two approaches, in which the primary end point was a 15-point difference on the EDITS score or a 20% difference in the IIEF-EF score. Results One hundred seventy-five patients were enrolled (57 in group 1, 118 in group 2) with 3- and 6-month follow-up at 57% and 35%, respectively, and similar between groups. Baseline patient characteristics and sexual function questionnaire responses were similar between groups 1 and 2, although group 1 reported higher-quality erections at baseline (QEQ score = 14.3 vs 7.3, P = .05) and had a smaller proportion of patients with prostatectomy (54.4% vs 74.6%, P = .02). In the two groups, QEQ score (mean = 10.78 vs 56.76, P < .05), SQoL score (mean = 38.41 vs 50.25, P < .05), and IIEF-EF score (mean = 7.51 vs 18.48, P < .05) improved with treatment. However, at 3 and 6 months, there were no statistically significant differences in responses for IIEF, QEQ, SQoL, or EDITS scores and no difference in failure or medication switch rates between groups. There were no significant differences in complication rates, although at 3 months group 2 reported a higher incidence of priapism and pain (23% vs 7.4%, P = .08). Conclusion Empiric and risk-based strategies for ICI therapy resulted in significant improvements across multiple domains of sexual function. Complication rates, satisfaction, and efficacy overall were similar between the two approaches. Clinicians can be reassured that no one approach to ICI therapy for ED management appears inferior to another.