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Premature ejaculation and erectile dysfunction prevalence and attitudes in the Asia-pacific region-a comment.

We read with interest the observational study by McMahon et al. concerning the prevalence of premature ejaculation (PE) and erectile dysfunction (ED) [1]. The authors used a 48-question survey that included the Premature Ejaculation Diagnostic Tool (PEDT) questionnaire. Data collection employed three different methods (computer-assisted interviewing, online, or in person) that varied among countries. They recruited 4,997 men, 68% of which were younger than 46 years, and concluded that PE is more prevalent than ED in the Asia-Pacific countries (31% vs. 5%). Moreover, they also noted that PEDT-diagnosed PE is more prevalent than self-reported PE (16% vs. 13%). As indicated by the authors, there are conflicting reports regarding the prevalence of PE, mainly due to lack of universally acknowledged criteria for diagnosis of PE and standards for designing observational studies at the time these surveys were carried out [2,3]. The high prevalence rates were generally not based on large-scale, broadly representative epidemiologic studies in which proper sampling methods were used [4]. Regrettably, this descriptive study has similar pitfalls, which make the prevalence of PE in this population questionable. First, the possible selection bias hampers the external validity of the results of the entire study. In surveys, selection bias may occur due to the nonrandom sampling and/or due to the participation status (i.e., volunteers tend to be more aware about the topic or nonresponders might represent a special group in which the disease is more frequent) [5]. Although it was pointed that a random sample of heterosexual men were surveyed, the crucial question “Which sampling method was used?” remains unanswered. Moreover, the authors omit to mention the overall response rate and the demographics of the nonparticipants, which do not allow us to evaluate possible selection bias and therefore make the results somewhat spurious. In addition, there are further indicators of bias in this study. Almost half of the respondents were 18–35 years of age and better educated. As the authors noted, the data collection via computer-assisted and online surveys requires a certain level of proficiency and may result in exclusion of older people and/or people within a lower socioeconomic class, among whom ED is more prevalent [6]. Therefore, the sample does not represent the actual population and valid conclusions cannot be made. We believe that the prevalence of ED is underestimated in this sample. The authors used PEDT in diagnosing PE patients, which has been developed to characterize Diagnostic and Statistical Manual of Mental Disorders, the fourth edition–Text Revision which defines PE as a “persistent or recurrent ejaculation with minimal sexual stimulation before, on, or shortly after penetration and before the person wishes it” [7–9]. However, as the authors clearly state in their article, this authority-based definition is not based on evidence and is difficult to apply consistently in diagnosing the condition, and its criteria are somewhat vague and open to interpretation by the clinician [10,11]. Therefore, a diagnostic tool that has been developed according to the criteria of an outdated definition is problematic. Hence, if one applies the criteria of the evidence-based definition from the International Society of Sexual Medicine, only 2.8% of the study population is diagnosed with lifelong PE, which is similar to what has already been published [12]. Finally, the authors noted a discrepancy between PEDTdiagnosed PE and self-reported PE, with only 40% of men with PEDT-diagnosed PE having self-reported PE. In other words, the specificity of PEDT in detecting self-reported PE patients is low. This finding is in accordance with a recent study where the sensitivity and specificity of PEDT were 89.3% and 50.5%, respectively [13]. As the diagnostic value of this tool has already been established, it is not a novel finding. In summary, in spite of the large sample size, this article provides limited understanding about the epidemiology of PE. We believe that additional well-designed cross-sectional studies with a special attention to selection bias are still needed.