Can the International Index of Erectile Function distinguish between organic and psychogenic erectile function?

To define the ability of the International Index of Erectile Function (IIEF) to differentiate between organic and psychogenic erectile dysfunction (ED).

Patients presenting for the evaluation and treatment of ED who had penile duplex Doppler ultrasonography (DUS) completed the IIEF questionnaire. Accepted ranges of the IIEF EF domain were used to grade baseline severity (severe, moderate and mild < or =11, 11-17, 18-25, respectively). Accepted criteria were used to define normality on DUS (peak systolic velocity >30 cm/s and end-diastolic velocity <5 cm/s). Patients with documented Peyronie's disease, hypogonadism and a history of radical prostatectomy were excluded.

In all, 112 patients were enrolled, with a mean (sd) age and duration of ED of 56 (16) and 2 (0.6) years, respectively. The vascular risk-factor profile included diabetes in 15%, hypertension in 26% and hyperlipidaemia in 20%. The baseline severity of ED was mild, moderate and severe in 28%, 41% and 32% men, respectively. All patients had normal testosterone levels. Patients also with a normal DUS were diagnosed with psychogenic ED, in 50%, 13% and 17% of men with mild, moderate and severe ED by the IIEF, respectively. No patient with venous leak had mild ED, and 62% of men with venous leak had severe ED.

These results indicate that the IIEF is not completely accurate in differentiating between organic and psychogenic ED, and that almost a fifth of men in this study population with severe ED by the IIEF had normal erectile haemodynamics. These data have potential ramifications for evaluating the baseline severity of ED in trials of erectogenic agents.