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Predicting major ischemic priapism: a novel dynamic nomogram based on recurrent ischemic priapism risk factors
Laurence T Hou1, Yuezhou Jing2, Bruce J Trock2
1Department of Urology, Hackensack University Medical Center, Hackensack, NJ 07601, United States.
Background:
Recurrent ischemic priapism (RIP) is a repetitive, self-remitting subtype of ischemic priapism with high risk of progression to major ischemic priapism (MIP), which can cause irreversible fibrosis and erectile dysfunction.
Aim:
To identify the risk factors for MIP in patients with RIP and develop a prognostic model and a RIP severity scoring system to predict future MIP events.
Methods:
We conducted a retrospective chart review of patients with RIP across a major academic health system (May 2006-November 2020). Demographic, clinical, and priapism characteristics were collected, and univariate and multivariable Poisson regression analyses were performed to identify predictors of MIP events per person-year (MIP PPY). Internal validation was performed using 10-fold cross-validation with mean absolute error as the performance metric. A web-based dynamic nomogram was created from significant risk factors, and patients were risk-stratified based on predicted MIP PPY.
Outcomes:
Primary outcome was the incidence rate ratio of MIP PPY predicted by significant risk factors.
Results:
Among 113 patients (mean age 32 years, mean follow-up 3 years), 225 MIP events were recorded over 557.5 person-years. Multivariable analysis identified longer priapism duration, adult-onset RIP (>25 years old), sickle cell disease, marijuana use, and tobacco smoking as independent predictors of increased MIP PPY. Patients were classified post hoc as low-risk (<1 MIP PPY, n = 81) or high-risk (≥1 MIP PPY, n = 32), with high-risk patients exhibiting longer priapism episodes, older age of onset, and higher recurrence rates.
Clinical Implications:
The nomogram offers an investigational tool for individualized risk estimation that, if validated, may help identify patients at higher risk of MIP and inform future study of preventive strategies.
Strengths And Limitations:
Strengths include the largest RIP cohort reported to date, robust statistical modeling, and creation of an interactive nomogram. Limitations include retrospective single-institution design, potential underreporting of priapism events, and lack of external validation, which may limit generalizability.
Conclusion:
This study identifies key MIP risk factors in patients with RIP, introduces a novel dynamic nomogram to predict future MIP events, and proposes a RIP severity scoring system that may improve risk stratification, inform treatment decisions, and guide future prospective studies.
