EXPERIMENTAL AND CLINICAL TRANSPLANTATION

Objectives: Erectile dysfunction is highly prevalent in men with end-stage renal disease and substantially impairs quality of life. Although kidney transplant can mitigate systemic complications, its effect on erectile dysfunction varies. Here, we evaluated 1-year changes in erectile function following living donor kidney transplant in Azerbaijani men and identified clinical predictors of postoperative improvement.
Materials and Methods: This retrospective observa-tional study included 121 male patients undergoing living donor kidney transplant between 2017 and 2024. Erectile function was evaluated with the 5-item International Index of Erectile Function preoperatively and at 6 and 12 months postoperatively. We used multivariate linear regression to identify independent predictors of improvement.
Results: All patients (mean age: 35.9 ± 11.7 y) had erectile dysfunction at baseline, predominantly mild-to-moderate (42.1%) or moderate (28.9%). Mean 5-item International Index of Erectile Function scores increased significantly from 11.0 ± 3.8 at baseline to 12.2 ± 4.1 at 6 months and to 14.0 ± 4.8 at 12 months (both P < .001). At 1 year, 97.5% of patients demon-strated improvement in score, with a mean increase of 3.0 ± 1.6 points. Univariate analysis linked older age, smoking, regular sexual partnerships, and mild baseline erectile dysfunction with greater increase in score. However, multivariate analysis established the base-line score as the sole independent predictor of 1-year erectile function improvement (P < .001).
Conclusions: Living donor kidney transplant was associated with significant and progressive improve-ment in erectile function over 1 year in men with end-stage renal disease. Baseline erectile function was the key determinant of recovery, underscoring the importance of early evaluation and management.

Key words : End-stage renal disease, Erectile dysfunction, IIEF-5, Renal transplantation

Erectile dysfunction (ED) is a highly prevalent condition among men with chronic kidney disease (CKD), particularly in those with end-stage renal disease (ESRD). The prevalence of ED in this population has been reported to approach 80%.¹ This condition has a profoundly negative impact on the overall well-being and quality of life of affected individuals.² Despite its high prevalence and substantial psychological burden, ED often remains underappreciated and underreported in routine clinical practice.
The pathophysiology of ED in patients with CKD is complex and multifactorial. The pathophysiology involves a combination of vascular, neurogenic, hormonal, and psychological factors.³ Specific contr-ibutors include disruptions in the hypothalamic-pituitary-gonadal axis, endothelial dysfunction, secondary hyperparathyroidism, and the adverse side effects of various medications.^1,4 Although hemodial-ysis is a life-saving intervention, hemodialysis does not reliably resolve sexual dysfunction. The hemodynamic and metabolic alterations associated with dialysis can sometimes even exacerbate ED symptoms.³
Kidney transplantation is considered the optimal treatment for ESRD, as it restores renal function and improves many systemic complications associated with uremia. Of note, transplant may reverse several key mechanisms underlying ED, including hormonal imbalances and endothelial dysfunction.⁴ Recent meta-analyses have shown that successful renal transplant substantially improves erectile function and increases serum testosterone levels compared with maintenance dialysis.^5,6 However, these benefits are not universal. Erectile dysfunction persists in approximately 20% to 50% of transplant recipients, indicating substantial interindividual variability in outcomes.⁵ Previous studies have suggested that factors such as patient age and baseline erectile function may influence postoperative improvement, although findings remain inconsistent.⁷
Despite these well-documented benefits, studies on the effects of kidney transplant on ED still present contradictory findings. The current literature is frequently limited by small sample sizes and heterogeneous study designs.⁵ Furthermore, data are scarce on sexual outcomes after kidney transplant in specific geographic and cultural settings, such as Azerbaijan. Therefore, in this study, we aimed to evaluate changes in erectile function over a 1-year follow-up period in Azerbaijani men with ESRD who underwent living donor kidney transplant (LDKT). In addition, we sought to identify clinical factors associated with postoperative improvements in erectile function.

Materials and Methods

Study design and population
This retrospective observational study included adult male patients with ESRD who underwent LDKT between June 2017 and December 2024. All surgical procedures and perioperative care were managed by a single transplant team. Procedures were initially performed at the Republican Diagnostic Center until 2022 and subsequently at the State Security Service Hospital.

Donor characteristics
All kidney transplant procedures included in this study were performed using living related donors or spousal donors, in accordance with national regul-ations and institutional ethical standards. No living unrelated donors were involved. Donors were relatives of the recipients within the first to fourth degree (including parents, siblings, aunts/uncles, cousins) or legally married spouses. All donors were aged ≥18 years at the time of donation.

Ethical considerations
The study protocol was approved by the Institutional Ethics Committee of the State Security Service Military Hospital. Because of the retrospective nature of the study and the anonymization of patient data, the requirement for informed consent was waived by the committee. The study was conducted in accor-dance with the ethical standards stated in the 1964 Declaration of Helsinki and its later amendments.

Transplant protocol and patient management
All procedures and perioperative management were conducted in accordance with the European Associa-tion of Urology⁸ and the Kidney Disease: Improving Global Outcomes guidelines.^9,10 Recipients under-went comprehensive pretransplant evaluation, inclu-ding assessment of comorbidities, infectious and malignant disease screening, and immunological compatibility testing. Living donors were evaluated for surgical suitability, renal function, and informed consent. Donor nephrectomy was performed lapa-roscopically for single-artery kidneys and via an open approach for grafts with multiple renal arteries. The graft was routinely implanted into the recipient’s right iliac fossa. Vascular anastomoses were performed in an end-to-side fashion to the external iliac vessels, and ureteroneocystostomy was performed using the extravesical Lich-Gregoir technique. Postoperative graft function was monitored using laboratory parameters, urine output, and Doppler ultrasonography. Immunosuppressive therapy consis-ted of induction with anti-thymocyte globulin or basiliximab, followed by maintenance therapy with a calcineurin inhibitor (preferably tacrolimus), mycop-henolate mofetil, and corticosteroids. Prophylaxis against opportunistic infections included valgan-ciclovir, trimethoprim-sulfamethoxazole, and nystatin. Graft biopsies were performed only in cases of suspected acute rejection.

Data collection and clinical assessments
We extracted baseline demographic and clinical characteristics retrospectively from institutional medical records. Recorded variables included patient age, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), donor-recipient relationship, etiology of ESRD, pretransplant hemodialysis duration, and the date of transplant. Renal function was assessed using the estimated glomerular filtration rate (eGFR) calculated at 3 distinct time points: preoperatively (baseline) and at 6 and 12 months postoperatively. Preoperative eGFR for the entire cohort was reported as a nominal descriptive value, with the acknowledgement that standard eGFR equations are not valid markers of true residual renal function for patients on maintenance dialysis, except for preemptive transplant recipients. Erectile function was evaluated with the validated 5-item International Index of Erectile Function (IIEF-5) questionnaire,¹¹ which was administered at the same time points. Based on IIEF-5 scores, the severity of ED was stratified into 5 categories: severe (score 5-7), moderate (8-11), mild-to-moderate (12-16), mild (17-21), and no ED (22-25). None of the patients received phosphodiesterase type 5 (PDE5) inhibitors or other targeted therapies for ED during the study period.

Study outcomes
The primary outcome of the study was the overall change in the IIEF-5 score from the preoperative baseline to the postoperative assessments following LDKT. Secondary outcomes included determining the prevalence and severity of ED before LDKT and identifying clinical factors associated with postoperative improvements in erectile function.

Statistical analyses
We used IBM SPSS Statistics version 27.0 (IBM Corp) for statistical analyses. We presented categorical data as frequencies (percentages) and continuous data as mean ± SD or median (range), as appropriate.
We verified assumption of normality with visual inspections and formal analytical tests. We evaluated within-group longitudinal changes and differences between independent groups using paired-samples and independent-sample t tests, respectively. We assessed bivariate associations with Spearman correlation. Finally, we incorporated variables demonstrating statistical significance (P < .05) in univariate analyses into a multivariable linear regression model to identify independent predictors. A 2-sided P < .05 was considered statistically significant.

Baseline characteristics
The study included 121 male patients; baseline reci-pient and donor characteristics are listed in Table 1. The mean patient age was 35.9 ± 11.7 years, and the mean BMI was 25.3 ± 4.2. Smoking was reported in 36 patients (29.8%), and diabetes and hypertension were present in 16 patients (13.2%) and 28 patients (23.1%), respectively. Fifty-eight patients (47.9%) reported having a regular sexual partner. All patients had ED at baseline, with most categorized as having mild-to-moderate severity (n = 51, 42.1%) or moderate severity (n = 35, 28.9%). The most common etiology of ESRD was of unknown origin (n = 54, 44.6%). Fifteen patients (12.4%) underwent preemptive transplant; among the 106 patients with non-pre-emptive transplant, the median pretransplant dialysis duration was 18 months (range, 1-120 mo). Mean age of donors was 48.1 ± 11.4 years, with 86 female donors (71.1%) and 99 related donors (81.8%).

Posttransplant renal and erectile function outcomes
Post-LDKT, the mean eGFR increased from 7.5 ± 3.7 to 67.3 ± 16.5 mL/min/1.73 m² at 6 months and to 68.3 ± 17.2 mL/min/1.73 m² at 12 months. Erectile function demonstrated continuous improvement over the 1-year follow-up period. The mean IIEF-5 score increased from 11.0 ± 3.8 at baseline to 12.2 ± 4.1 at 6 months (mean change of 1.2 ± 0.8; P < .001) and then to 14.0 ± 4.8 at 12 months (mean change of 1.8 ± 1.3; P < .001) (Figure 1). At 12 months, 97.5% of patients demonstrated an increase in IIEF-5 score compared with baseline. The mean change in IIEF-5 score at 1 year was 3.0 ± 1.6 (range, 0-7).

Factors associated with 1-year improvement in erectile function
Spearman correlation analysis revealed a strong positive correlation between the 1-year change in IIEF-5 score and the baseline IIEF-5 score (r = 0.53, P < .01). A positive correlation was also observed between the 1-year change in IIEF-5 score and patient age (r = 0.22, P < .05). No significant correlations were shown between the 1-year change in erectile function and BMI (r = 0.08), dialysis duration (r = 0.14), 1-year eGFR (r = -0.12), or 1-year change in eGFR (r = -0.13) (Figure 2). Univariate analysis identified specific factors associated with the 1-year change in IIEF-5 score (Table 2). Patients older than 40 years exhibited a significantly greater mean improvement in their 1-year score than those aged 18 to 40 years (3.6 ± 1.6 vs 2.7 ± 1.5; P = .004). Smoking was similarly asso-ciated with greater improvement in IIEF-5 score (3.5 ± 1.4 vs 2.8 ± 1.7; P = .049). Patients with a regular sexual partner also demonstrated a larger mean score increase than those without a partner (3.4 ± 1.6 vs 2.7 ± 1.5; P = .006). Furthermore, patients with mild baseline ED (score > 11) experienced a greater impro-vement compared with those with moderate-to-severe baseline ED (score ≤ 11) (3.5 ± 1.2 vs 2.6 ± 1.8; P = .004). Of note, undergoing preemptive transplant did not confer a significant advantage in terms of initial baseline erectile function (P > .05) or the 1-year change in IIEF-5 score (3.1 ± 1.8 vs 3.0 ± 1.6; P = .931) compared with non-preemptive transplant.
To identify independent predictors of erectile function improvement, a multivariate linear regression analysis was performed, in which variables that were statistically significant in the univariate analysis were incorporated. Analyses identified baseline IIEF-5 score as the only independent factor significantly associated with the 1-year change in erectile function (B = 0.203; 95% CI, 0.135-0.270; P < .001) (Table 3).

The present study aimed to evaluate the longitudinal changes in erectile function among Azerbaijani men with ESRD following LDKT and to identify clinical predictors of postoperative improvement. Our fin-dings demonstrated that LDKT leads to a continuous and significant improvement in erectile function over a 1-year follow-up period. Although 100% of our cohort experienced ED prior to LDKT, 97.5% of the patients exhibited an increase in their IIEF-5 scores at 12 months, with a mean overall improvement of 3.0 points. Notably, the multivariable analysis identified the baseline IIEF-5 score as the sole independent predictor of this postoperative improvement.
Our observed mean IIEF-5 score increase of 3.0 points aligns remarkably well with a comprehensive meta-analysis by Pyrgidis and colleagues,¹² who reported a pooled mean increase of 3.04 points follo-wing kidney transplant. The progressive recovery of sexual function documented in our cohort has been also corroborated by recent prospective data showing significant increases in total IIEF scores at 1-year posttransplant.¹³ Several meta-analyses have consis-tently confirmed that successful kidney transplantation improves erectile function, increases sexual desire, and reduces the overall severity of ED compared with maintenance dialysis.^6,14,15 The robust improvements seen in our study may be partially attributed to the exclusive use of living donor grafts, as recent work has indicated that LDKT recipients experience greater sexual function recovery than recipients of kidneys from deceased donors.¹⁵
Despite the general consensus that kidney transplant exerts a protective and restorative effect on sexual health, the literature remains somewhat contradictory. For example, in a retrospective analysis, Spirito and colleagues¹⁶ reported a parado-xical worsening of both erectile and ejaculatory func-tions at 6 and 12 months posttransplant. Similarly, Yavuz and colleagues¹⁷ found no significant differen-ce in the pre-valence of ED between patients under-going hemodialysis and those who received a renal transplant. These discrepancies likely stem from high heterogeneity across study designs, varying degrees of baseline comorbidities (such as advanced age, prolon-ged diabetes, and profound vascular disease), and differences in graft quality or immunosuppressive regimens.
A critical finding of our analysis was the identification of baseline erectile function as the only independent predictor of 1-year postoperative improvement. Patients with mild baseline ED demonstrated significantly greater recovery than those with moderate-to-severe ED. This observation strongly correlates with the findings of Pyrgidis and colleagues,¹² who noted that renal transplant offered no favorable effect for individuals with seve-re preoperative ED. El Hennawy and colleagues¹⁸ similarly observed that the most pronounced impro-vements occurred in patients who presented with mild pretransplant ED. This finding suggests that severe ED in ESRD may reflect irreversible structural changes, such as severe cavernosal endothelial damage or autonomic neuropathy, which cannot be salvaged simply by restoring renal clearance.
Of note, we found no significant correlation between the duration of pretransplant dialysis and the degree of erectile function improvement. This finding is consistent with some reports in the literature,¹⁸ although it contradicts others that suggest prolonged hemodialysis negatively affects postoperative sexual recovery.^19,20 Furthermore, although univariate analysis indicated that age greater than 40 years, a history of smoking, and having a regular sexual partner were associated with greater absolute score increases, these factors did not retain significance in the multivariable model. This underscores that the preexisting functional capacity of the penile tissue overshadows demographic factors in determining reversibility.
The physiological mechanisms driving the obser-ved improvements in our cohort likely involve the systemic clearance of uremic toxins and the resolu-tion of endocrine derangements. Previous studies have established that successful kidney transplant significantly increases serum testosterone while decreasing prolactin and luteinizing hormone levels compared with patients on dialysis.^6,19,21 Although sex hormone profiles were not routinely measured in our retrospective cohort, the continuous score improvement from 6 to 12 months likely mirrors this gradual hormonal normalization alongside improve-ments in endothelial function.
Despite the significant improvements that were recorded, it is essential from a clinical perspective to acknowledge that the final mean IIEF-5 score at 12 months was 14.0, which still categorizes these patients as having mild-to-moderate ED. As highlighted by Dell’Atti,²² between 20% and 50% of transplant recipients continue to experience ED due to multi-faceted causes, including drug side effects, residual vascular impairment, and psychological anxiety. Consequently, kidney transplant should be viewed as a facilitator of sexual health rather than an absolute cure. For the persistent ED observed in these populations, adjunct therapies are frequently required.¹⁵ Phosphodiesterase type 5 inhibitors remain the first-line treatment and have demonstrated excellent safety and efficacy profiles in renal transplant recipients.^22,23 However, clinicians must remain vigi-lant regarding potential drug-drug interactions; for example, the concurrent use of sildenafil and calcineurin inhibitors such as tacrolimus may alter the pharmacokinetics of the PDE5 inhibitor and provoke pronounced hypotensive episodes, neces-sitating careful dose titration.²⁴
The present study had several notable strengths. Our study is the first to evaluate the trajectory of erectile function after kidney transplant in an Azerbaijani population, thereby contributing valuable data from an underrepresented demographic. Furthermore, the inclusion of a highly homogeneous cohort minimized the confounding variables typically associated with mixed donor types and disparate perioperative protocols. However, the study had some limitations. First, the retrospective design restricted our ability to infer definitive causality. In addition, the lack of endocrinological data such as testosterone and prolactin levels limited our capacity to correlate clinical improvements directly with hormonal recovery. We also lacked data concerning the sexual function of the recipients’ partners and the specific psychological effects of the transplant process, both of which are known to influence IIEF-5 outcomes. Because none of the patients in our cohort used targeted ED therapies during the follow-up period, our results reflected the natural evolution of erectile function posttransplant; however, future prospective trials should evaluate the efficacy of early, combined interventions (eg, PDE5 inhibitors or testosterone replacement) in this specific population.

Living-donor kidney transplant was associated with a significant and progressive improvement in erectile function among men with ESRD over a 1-year period. The severity of pretransplant ED served as the most critical independent predictor of posto-perative recovery, emphasizing the importance of early diagnosis and intervention before irreversible cavernosal damage occurs. Although transplant provides substantial benefits, residual ED remains common, underscoring the need for a multi-disciplinary approach and the judicious integration of targeted pharmacological therapies to optimize the quality of life in renal transplant recipients.

Volume: 24 Issue: 7 July 2026

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