Medication Utilization Behavior in Patients Receiving Phosphodiesterase Type 5 Inhibitors for Erectile Dysfunction

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Abstract
A number of preference studies have been conducted with phosphodiesterase type 5 (PDE5) inhibitor medications demonstrating inconsistent findings. Additionally, limited information is available regarding real-world utilization patterns of PDE5 inhibitors. To evaluate treatment patterns using real-world data for patients initiating erectile dysfunction (ED) therapy with Viagra (sildenafil citrate), Levitra (vardenafil), or Cialis (tadalafil). Patients with an initial prescription claim for sildenafil, vardenafil, or tadalafil were identified in NDCHealth's Intelligent Health Repository. Medication refills, medication switching, and dose titration were analyzed. Logistic regression on the odds of refilling initial PDE5 medications was conducted controlling for patient age, presence of common comorbidities, initial number of tablets, and copay. A higher percentage of patients receiving sildenafil (52%) refilled their ED medication during the study period than patients receiving vardenafil (30%) or tadalafil (29%) (P<0.001). A smaller percentage of patients in the sildenafil cohort (6.4%) switched medication than in the tadalafil (9.0%) or vardenafil (10.4%) cohorts (P<0.001); the difference between the tadalafil and vardenafil cohorts in switching medications was also significant (P<0.001). There were no statistically significant differences between cohorts in dose titration frequency, which was low in all three treatment cohorts. Using logistic regression, the odds of refilling initial PDE5 therapy was significantly lower for vardenafil (odds ratio [OR]: 0.39, 95% confidence interval [CI]: 0.38-0.40; P<0.0001) and tadalafil (OR: 0.38, 95% CI: 0.37-0.40; P<0.0001) compared with sildenafil. Patients who were initially prescribed sildenafil were significantly more likely to refill their medication and significantly less likely to switch medications during the study period compared with patients who were initially prescribed vardenafil or tadalafil. These findings may indicate greater treatment satisfaction in patients receiving sildenafil, although future prospective evaluation is required.