Peyronie’s disease (PD) is caused by progressive fibrotic scarring of the tunica albuginea resulting in curvature or other deformities of the erect penis. The severity of penile curvature or other deformity may contribute to a man’s inability to have intercourse (sexual disability), due to difficulty with penetration, partner pain or emotional stress. To determine whether the degree of curvature or type of penile deformity predicts sexual disability among men with PD. This cross-sectional analysis of consecutive men evaluated for PD at a single tertiary referral center used a PD-specific questionnaire to evaluate risk factors for sexual disability in men with PD, who did not have erectile dysfunction (ED). Multivariate logistic regression was used to determine the clinical predictors of sexual disability. Sexual disability as defined by the inability to have penetrative intercourse. A total of 202 men were evaluated and 88 men with ED were excluded. Sexual disability was associated with relationship problems, penile curvature and penile length loss in bivariate, but not multivariate analysis. We found that although many of the demographic, medical and sexual function domains were significant predictors of inability to have sex, the only significant predictor of sexual disability in multivariate analysis was curvature>60° (odds ratio 3.23 95%CI 1.08–9.67). PD can be sexually disabling in many men without ED. Severe penile curvature is a robust independent predictor of the ability to have intercourse. Other penile deformities fail to predict sexual disability. This is important for counseling patients with newly diagnosed PD and those who are considering medical or surgical intervention.
Peyronie’s disease (PD) is a poorly defined localized connective tissue disorder caused by progressive fibrotic scarring of the tunica albuginea of the corpora cavernosa, resulting in curvature or other deformities of the erect penis.1, 2, 3 The prevalence of PD is estimated at 3.7–7.1% of men and as high as 16% in men undergoing evaluation for erectile dysfunction (ED).1, 2, 4, 5, 6
ED rarely occurs as a result of PD and the impact of PD on erectile function is poorly characterized.7 In spite of this, many studies of PD have used tools that were developed to assess ED, such as the International Index of Erectile Function to determine the degree of sexual dysfunction in evaluating severity of PD.8, 9 Although ED assessment is a key part of the evaluation of the PD patient, the severity of penile curvature or other penile deformity may contribute to a man’s inability to have intercourse, and is often one of the primary factors prompting emotional distress and surgical intervention.10, 11, 12, 13
To clarify the relationship between PD-specific penile abnormalities and sexual disability, we assessed whether the degree of curvature or type of penile deformity was associated with sexual disability among men with PD who did not have ED.
Materials and methods
We performed a cross-sectional analysis of consecutive men evaluated for PD at a single tertiary referral center. Men with PD were characterized using a nonvalidated PD-specific questionnaire that was completed at the time of initial evaluation.10 Information collected by the questionnaire included demographic characteristics, PD associated symptoms, medical comorbidities, past surgical history and prior treatments for PD. Specific variables assessed included age, duration of disease, marital status, history of DM, history of hypertension, ED status (defined by ability to maintain or achieve an erection), libido, emotional and relationship stress from PD, penetration difficulty and partner pain. Questionnaire data was supplemented by a comprehensive clinical evaluation performed by a single Peyronie’s expert (Tom Lue) that included a detailed review of all questionnaire data, including self-reported: degree and direction of curvature, the presence and location of hinge deformity, hourglass deformity, penile length loss and softening distal to plaque. This study was approved by the University of California San Francisco Committee on Human Subjects.
Main outcome measures
The primary outcome was sexual disability defined as the inability to have sexual intercourse. The specific question asked was, ‘Are you currently capable of sexual intercourse?’ (yes/no).
We used an a priori model for the impact of penile deformity on sexual function to frame our analysis (Figure 1). Given our intent to understand the impact of penile deformity on sexual disability independent of ED, men with self described ED (by answering yes to ‘do you have the ability to maintain and erection adequate for intercourse?’) were excluded from the analyses (n=88). Clinical characteristics were compared between men with and without sexual disability (n=114).
After dichotomizing men by sexual disability status we compared the two groups using a P-value<0.05 from a two-sided t-test as the threshold for statistical significance. Predictor variables were chosen for inclusion based on our a priori model (Figure 1).
We used bivariate and multivariate logistic regression to evaluate potential predictors of sexual disability. Odds ratios (OR) and their 95% confidence intervals were used as a measure of association between predictors and outcome. We analyzed age as a continuous variable and all other demographic, medical and sexual function variables as binary (yes/no) responses. Penile deformity characteristics were coded as binary responses for penile length loss, hourglass deformity, hinge deformity at the head or base and softening distal to the plaque. Penile curvature was initially recorded in degrees and recoded per the modified Kelami classification into mild (<30°), moderate (30−60°) or severe (>60°).14 Only men with complete covariate data were used for this analysis. All analyses were completed using STATA 11 (StataCorp, College Station, TX, USA).
A total 202 men completed the PD-specific questionnaire and had a complete clinical evaluation. Among these, 88 (45%) men were excluded due to concomitant ED identified by the International Index of Erectile Function questionnaire. The remaining men had a mean age 54.3 years (range 25–77) and had the following distribution penile curvature severity: mild—38% (21% sexual disability), moderate—34% (28% sexual disability) and severe—28% (57% sexual disability). Notably, men with and without sexual disability did not differ with regard to directionality or location of penile curve (data not shown).
Sexual disability was associated with relationship problems, penile curvature and penile length loss (Table 1). Men with sexual disability were significantly more likely to have penetration difficulty due to penile curvature (82 vs 62%, P=0.04), partner pain due to penile curvature (32 vs 14%, P=0.05), a higher proportion with severe penile curvature (63 vs 38%, P<0.001) and a higher proportion of subjective penile length loss (93 vs 79%, P=0.05).
Analysis of risk factors of sexual disability
Although many of the demographic, medical and sexual function variables were significant predictors of inability to have sex in bivariate analyses the only significant predictor of sexual disability in multivariate analysis was curvature>60° (odds ratio 3.23 95%CI 1.08–9.67) (Table 2, Figure 2). None of the other penile deformity characteristics were statistically significant independent predictors of sexual disability.
In this cross-sectional study of self-reported penile deformity and sexual function, we have found that PD can be sexually disabling in greater than 30% of men who do not have ED. Severe penile curvature is a significant independent predictor of the ability to have intercourse, all other penile deformities and other areas of sexual function fail to predict sexual disability. Further, unlike previous studies,2, 8, 15, 16 we failed to identify an independent association between DM and sexual disability in a population of men without ED.
In this group of men with PD (without ED), penile curvature greater than 60 degrees conferred a more than threefold increase in the odds of sexual disability. Despite the fact that ED occurs rarely as the direct result of PD,7 much of the current PD literature focuses on ED as the primary endpoint in evaluating PD.8, 9, 17 Recent work has demonstrated that severity of penile curvature is one of the main factors contributing to sexual disability, emotional distress and surgical intervention.10, 11, 12 Previous studies of PD that included men with and without ED in their study population may have confounded their analyses by examining factors that predict severity of ED in addition to sexual disability from PD.18, 19
As sexual disability has been shown to influence the need for surgical intervention, careful determination of the severity of penile curvature in men without ED may be an important tool for counseling men with newly diagnosed PD.10
Our work demonstrated that only severe curvature and not demographics, medical comorbidities, sexual function parameters or other penile deformity characteristics predicted sexual disability. Previous work has implicated DM as being associated with the severity of penile curvature;8, 9, 16, 18 however, data from our cohort did not support this observation. Work by Saigal et al.19 has demonstrated that advanced age, DM, hypertension and obesity were significantly associated with ED in multivariate analysis on a population level. It is well-known that men with ED are more likely to be evaluated by a urologist and to have PD diagnosed.6 Evaluating all men with PD regardless of ED status likely introduces some confounding into risk factors for PD. Although it is clear that erectile function is a major contributor to reduced quality of life in men with PD,20 severe penile curvature among men with normal erectile function is an additional predictor of impaired sexual function.
A simple multivariate model adjusting for degree of curvature, age and DM identified only degree of curvature as being predictive of sexual disability (data not shown). By limiting our analysis to men without ED, we did not find that age or DM was associated with what we have identified as one of the most clinically relevant parameters of PD disability, sexual disability.
Our study has some significant limitations. Although there were 584 men evaluated for PD, only 202 completed both the PD-specific questionnaire and a comprehensive clinical evaluation, and were available for analysis. Some selection bias could have been introduced by non-differential misclassification; which would tend to bias measures of association toward the null hypothesis. There also may have been an unwillingness to complete the sensitive questions related to sexual disability, which may have biased our results. The penile deformity characteristics that were used to predict outcome were self-reported, and therefore may be prone to reporting bias. The outcome measures in this study have not been validated, thus decreasing the chance that they accurately measure what they attempt to measure. Importantly, this is a cross-sectional, self-assessment, and the exact reasons for why a man is unable to have intercourse cannot be determined without a focus-group type of study. In some cases, a specific physical or mechanical limitation may be the reason for why a man cannot have sexual intercourse. However, other men are may be unable to have sexual intercourse for reasons of personal pain, partner pain, embarrassment or other psychological stresses. It is for these reasons that we intend the phrase ‘sexual disability’ to imply a broader scope of reasons for a man’s inability to have sex.
Although these findings are certainly hypothesis generating they are subject to institutional bias and selection bias, and will need to be verified in additional studies to confirm their validity.
PD can be sexually disabling in many men without ED. Severe penile curvature is an independent predictor of the ability to have intercourse. Other penile deformities fail to predict sexual disability. This is important for counseling patients who are considering medical or surgical intervention.
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The authors declare no conflict of interest.
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Cite this article
Walsh, T., Hotaling, J., Lue, T. et al. How curved is too curved? The severity of penile deformity may predict sexual disability among men with Peyronie’s disease. Int J Impot Res 25, 109–112 (2013). https://doi.org/10.1038/ijir.2012.48
- erectile dysfunction
- peyronie’s disease
- sexual disability
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