Validity of Erectile Function Assessment Questionnaires in Premature Ejaculation Patients: A Comparative Study Between the Abridged Forms of the International Index of Erectile Function and Proposal for Optimal Cutoff Redefinition

Abstract

Background: Patients with premature ejaculation (PE) are often diagnosed as having a comorbid erectile dysfunction (ED). When evaluating erectile function in PE patients with the popular International Index of Erectile Function-5 (IIEF-5, or Sexual Health Inventory for Men [SHIM]), question #5 (Q5) about sexual satisfaction in the intercourse often lowers the total score of the questionnaire, giving false-positive results for the presence of ED.

Aim: We aimed to compare SHIM with the other abridged form of IIEF, which is IIEF-EF, and to discriminate which tool has the best diagnostic accuracy in the evaluation of erectile function in PE patients.

Methods: The study was conducted from March 2019 to January 2020. A total of 189 heterosexual males with lifelong PE (117, 61.9%) or acquired PE (72, 38.1%) were included. They all compiled Premature Ejaculation Diagnostic Tool, IIEF-15, SHIM, and IIEF-EF and underwent a full clinical examination to evaluate their erectile function.

Outcomes: The scores of the 2 erectile function assessment questionnaires (SHIM and IIEF-EF) were compared in terms of their sensitivity and specificity in the diagnosis of ED in PE patients.

Results: In terms of diagnosing ED in PE patients, the sensitivity of SHIM is 100% while the specificity is only 36%; meanwhile, the sensitivity of IIEF-EF is 100% but specificity is 77.2%. Further analysis demonstrates that decreasing cutoff of SHIM to 17.5 would provide an increased specificity of 82.5%, while sensitivity would lower to 96.0%. However, the highest area under the curve (0.966 vs 0.941) is given by the IIEF-EF with 100% sensitivity and 80.7% specificity at the cutoff of 24.5, which is one point lower than the usual cutoff value of 25.5.

Clinical implications: Our study suggests that when evaluating erection function in PE patients, the cutoff of both SHIM and IIEF-EF should be amended.

Strengths & limitations: We proposed the solution for the bias of erectile function assessment in PE patients. However, other trials are needed to further validate in larger cohorts of PE patients.

Conclusion: We suggest that the cutoff of SHIM and IIEF-EF should be amended (SHIM at 17.5 and IIEF-EF at 24.5, respectively) when assessing erectile function among PE population. Xi Y, Colonnello E, Ma G, et al. Validity of Erectile Function Assessment Questionnaires in Premature Ejaculation Patients: A Comparative Study Between the Abridged Forms of the International Index of Erectile Function and Proposal for Optimal Cutoff Redefinition. J Sex Med 2021;18:440-447.

Keywords: Erectile Function; International Index of Erectile Function; Premature Ejaculation; Sexual Health Inventory for Men.