Perioperative outcomes of penile prosthesis implantation in Germany: results from the GRAND study

Penile prosthesis implantation (PPI) is the standard treatment for refractory erectile dysfunction (ED) and includes inflatable and semi-rigid devices. Semi-rigid devices have lower material costs and are suitable for patients with limited manual dexterity but result in persistent, less natural erections, whereas inflatable devices provide more natural function and concealability, leading to patient preference. Approximately 15,000 PPIs are performed annually worldwide, with >85% in the USA and Germany contributing about 2.5%. The inflatable-to-semi-rigid ratio in the USA is roughly 10:1. It is recommended that PPI be performed by surgeons with at least one case per month. Despite PPI’s safety, it has been hypothesized that inflatable PPI might have higher morbidity and longer hospital stays than semi-rigid PPI; however, large nationwide comparative studies are scarce. Evidence suggests higher annual hospital volume may improve outcomes and has driven centralization. Thresholds for optimal annual caseload are better studied in the USA than elsewhere. There is a lack of data on trends and outcomes in Germany. This study aims to determine recommended annual hospital volume for inflatable PPI and to compare perioperative outcomes of semi-rigid versus inflatable PPI using nationwide German data.

Prior studies, primarily from the USA, suggest that higher annual hospital or surgeon volume for PPI is associated with improved perioperative and long-term outcomes, including shorter operative times and fewer complications. The literature indicates a preference for inflatable devices and a move toward centralization in centers of excellence. However, head-to-head comparisons of inflatable versus semi-rigid PPI and robust nationwide data outside the USA are limited. German nationwide, real-world perioperative outcome data had not been previously reported, and optimal annual caseload thresholds outside the USA remain unclear.

Design and data source: Retrospective analysis of the GeRmAn Nationwide inpatient Data (GRAND) from 2005–2021, covering virtually all inpatient cases in Germany (excluding psychiatric and military). Data are anonymized and provided by the Research Data Center of the Federal Bureau of Statistics. Population: All patients undergoing first-time PPI were included; semi-rigid devices identified via procedural codes (e.g., DSO 654911). Inflatable versus semi-rigid PPI cohorts were defined, and inflatable PPI cases were stratified by annual hospital caseload. Exposure definition: Hospitals performing inflatable PPI were identified by postal code. Centers were categorized by annual volume into low-volume (<20 inflatable PPI/year) and high-volume (≥20 inflatable PPI/year). Outcomes: Primary analyses compared low- versus high-volume centers on postoperative complications (sepsis, ICU admission, mortality, urinary tract infection, surgical wound infection) and length of hospital stay. Secondary analyses compared perioperative complications and length of hospital stay between semi-rigid and inflatable PPI and assessed temporal trends in PPI in Germany. Statistical analysis: Categorical variables were reported as frequencies (%) and compared via chi-squared tests; continuous variables (normally distributed) were reported as mean ± SD and compared via t-tests. Multivariable logistic and linear regression models assessed associations of hospital volume and PPI type with complications and length of stay, adjusting for age, obesity, diabetes, and prior pelvic radiation. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported; p<0.05 deemed significant. Analyses were executed by the Research Data Center using R code provided by the authors. To ensure anonymity, outcomes with fewer than three events were suppressed. Ethics approval and patient consent were not required due to the use of anonymized administrative data.

- Sample: 7,222 first-time PPI patients (2005–2021): 6,818 (94.4%) inflatable; 404 (5.6%) semi-rigid. - Baseline differences: Inflatable recipients were older and more likely to have hypertension; priapism more frequent among semi-rigid recipients. - Length of stay (LOS): Mean LOS 7.4 ± 5 days (inflatable) vs 9.7 ± 9 days (semi-rigid). Adjusted difference: inflatable associated with shorter LOS by ~2.2 days (95% CI: 1.6–2.7; p<0.001). - Infections: Inflatable associated with lower odds of urinary tract infection (5.5% vs 9.2%; OR 0.58; 95% CI 0.41–0.84; p=0.003) and surgical wound infection (1.0% vs 2.5%; OR 0.42; 95% CI 0.22–0.88; p=0.012) versus semi-rigid. - ICU admission: No significant difference (0.72% vs 1%; OR ~0.67; 95% CI ~0.27–2.2; not significant). - Mortality and sepsis: Not assessable due to suppression of cells with <3 events. - Volume stratification (inflatable PPI): 4,255 (62.4%) low-volume centers (<20/year) vs 2,563 (37.6%) high-volume centers (≥20/year). - Volume-outcome: High-volume centers associated with shorter LOS by 1.4 days (95% CI: 1.2–1.7; p<0.001); no significant differences in urinary tract infection, surgical wound infection, or ICU admission between volume groups. - Trends: Inflatable PPI volume increased over time (e.g., 165 cases in 2005 to 433 in 2019); both device types declined during the COVID-19 pandemic (e.g., 2021: 496 inflatable; 30 semi-rigid).

This nationwide analysis indicates that PPI is a safe option for refractory ED with low perioperative complication rates. Inflatable PPI is associated with shorter hospital stays and lower rates of urinary tract and surgical wound infections compared to semi-rigid devices, supporting the prevailing clinical preference for inflatable implants. While higher hospital case volume for inflatable PPI correlates with reduced length of stay, it does not significantly impact perioperative infection rates or ICU admissions, suggesting that centralization may offer efficiency benefits without clear short-term complication differences. The study fills a gap in German real-world data and provides head-to-head perioperative comparisons that have been limited in prior literature. Pandemic-related healthcare disruptions likely contributed to the observed decline in PPI volumes in 2020–2021.

Inflatable penile prosthesis implantation is associated with shorter hospitalization and lower perioperative urinary tract and wound infection rates than semi-rigid implantation. High-volume centers discharge inflatable PPI patients earlier, though perioperative infectious complication rates are similar across volume strata. Ongoing monitoring of PPI practice patterns and outcomes is warranted, particularly in the context of COVID-19-related care disruptions. Future research should refine volume thresholds, incorporate patient-level clinical covariates, and assess long-term functional outcomes and revisions.

- Use of anonymized administrative data with no direct patient-level access; analyses based on summary results provided by the Research Data Center. - Suppression of rare outcomes (<3 events) precluded assessment of in-hospital mortality and sepsis. - Potential coding inaccuracies and lack of granular clinical variables (e.g., operative time, surgeon volume, device specifics, perioperative protocols). - Observational retrospective design limits causal inference; residual confounding may persist despite adjustment. - Some inconsistencies/typographical issues in reported summary tables may affect interpretation of specific subgroup counts.