Development, multi-institutional external validation, and algorithmic audit of an artificial intelligence-based Side-specific Extra-Prostatic Extension Risk Assessment tool (SEPERA) for patients undergoing radical prostatectomy: a retrospective cohort study

BACKGROUND

Accurate prediction of side-specific extraprostatic extension (ssEPE) is essential for performing nerve-sparing surgery to mitigate treatment-related side-effects such as impotence and incontinence in patients with localised prostate cancer. Artificial intelligence (AI) might provide robust and personalised ssEPE predictions to better inform nerve-sparing strategy during radical prostatectomy. We aimed to develop, externally validate, and perform an algorithmic audit of an AI-based Side-specific Extra-Prostatic Extension Risk Assessment tool (SEPERA).

METHODS

Each prostatic lobe was treated as an individual case such that each patient contributed two cases to the overall cohort. SEPERA was trained on 1022 cases from a community hospital network (Trillium Health Partners; Mississauga, ON, Canada) between 2010 and 2020. Subsequently, SEPERA was externally validated on 3914 cases across three academic centres: Princess Margaret Cancer Centre (Toronto, ON, Canada) from 2008 to 2020; L'Institut Mutualiste Montsouris (Paris, France) from 2010 to 2020; and Jules Bordet Institute (Brussels, Belgium) from 2015 to 2020. Model performance was characterised by area under the receiver operating characteristic curve (AUROC), area under the precision recall curve (AUPRC), calibration, and net benefit. SEPERA was compared against contemporary nomograms (ie, Sayyid nomogram, Soeterik nomogram [non-MRI and MRI]), as well as a separate logistic regression model using the same variables included in SEPERA. An algorithmic audit was performed to assess model bias and identify common patient characteristics among predictive errors.

FINDINGS

Overall, 2468 patients comprising 4936 cases (ie, prostatic lobes) were included in this study. SEPERA was well calibrated and had the best performance across all validation cohorts (pooled AUROC of 0·77 [95% CI 0·75-0·78] and pooled AUPRC of 0·61 [0·58-0·63]). In patients with pathological ssEPE despite benign ipsilateral biopsies, SEPERA correctly predicted ssEPE in 72 (68%) of 106 cases compared with the other models (47 [44%] in the logistic regression model, none in the Sayyid model, 13 [12%] in the Soeterik non-MRI model, and five [5%] in the Soeterik MRI model). SEPERA had higher net benefit than the other models to predict ssEPE, enabling more patients to safely undergo nerve-sparing. In the algorithmic audit, no evidence of model bias was observed, with no significant difference in AUROC when stratified by race, biopsy year, age, biopsy type (systematic only vs systematic and MRI-targeted biopsy), biopsy location (academic vs community), and D'Amico risk group. According to the audit, the most common errors were false positives, particularly for older patients with high-risk disease. No aggressive tumours (ie, grade >2 or high-risk disease) were found among false negatives.

INTERPRETATION

We demonstrated the accuracy, safety, and generalisability of using SEPERA to personalise nerve-sparing approaches during radical prostatectomy.

FUNDING

None.

Explainable artificial intelligence to predict the risk of side-specific extraprostatic extension in pre-prostatectomy patients

Introduction: We aimed to develop an explainable machine learning (ML) model to predict side-specific extraprostatic extension (ssEPE) to identify patients who can safely undergo nerve-sparing radical prostatectomy using preoperative clinicopathological variables. Methods: A retrospective sample of clinicopathological data from 900 prostatic lobes at our institution was used as the training cohort. Primary outcome was the presence of ssEPE. The baseline model for comparison had the highest performance out of current biopsy-derived predictive models for ssEPE. A separate logistic regression (LR) model was built using the same variables as the ML model. All models were externally validated using a testing cohort of 122 lobes from another institution. Models were assessed by area under receiver operating characteristic (AUROC), precision-recall (AUPRC), calibration, and decision curve analysis. Model predictions were explained using Shapley Additive exPlanations. This tool was deployed as a publicly available web application. Results: Incidence of ssEPE in the training and testing cohorts were 30.7 and 41.8%, respectively. The ML model achieved AUROC 0.81 (LR 0.78, baseline 0.74) and AUPRC 0.69 (LR 0.64, baseline 0.59) on the training cohort. On the testing cohort, the ML model achieved AUROC 0.81 (LR 0.76, baseline 0.75) and AUPRC 0.78 (LR 0.75, baseline 0.70). The ML model was explainable, well-calibrated, and achieved the highest net benefit for clinically relevant cutoffs of 10–30%. Conclusions: We developed a user-friendly application that enables physicians without prior ML experience to assess ssEPE risk and understand factors driving these predictions to aid surgical planning and patient counselling (www.ssepe.ml).

Do post-operative phone calls enhance family satisfaction and outcomes after outpatient pediatric urological surgeries? A prospective study

INTRODUCTION

This study assesses whether post-operative check-in phone calls (POPC) performed within 48 h of outpatient pediatric urological surgeries by a non-medical professional (NMP) would increase patient/family satisfaction and minimize extraneous resource use by increasing email/telephone communication, while reducing emergency department (ED) visits within 30 days of that procedure.

METHODS

Families of patients undergoing ambulatory pediatric urology surgeries were enrolled over 8 weeks. Group 1 did not receive POPC. Group 2 received a POPC within 48 h of their operation by a NMP. Both groups received a phone-call survey 2 weeks after surgery to assess families' perioperative satisfaction.

RESULTS

In total, 74 families were enrolled (Group 1 = 44, Group 2 = 31). The response rates to phone surveys for Groups 1 and 2 were 59.1% and 77.4%, respectively. POPC did not improve perioperative satisfaction, nor did it significantly promote the use of nursing email/telephone communication (19.2% vs. 4.2%, p = 0.128) or reduce ED visits (15.4% vs. 0.0%, p = 0.111). However, all families in Group 2 thought POPC was timed appropriately and 79.1% perceived it to be helpful in reducing post-operative anxiety.

CONCLUSION

POPC by a NMP within 48 h of surgery may not affect perioperative satisfaction of families of patients undergoing same-day pediatric urology surgery but may have an impact in reducing post-operative anxiety.

Variability among Canadian pediatric surgeons and pediatric urologists in the management of cryptorchidism in boys before the publication of major guidelines: a retrospective review of a single tertiary centre

Background

Before 2014, there was a lack of recommendations on managing cryptorchidism, or undescended testis (UDT), from a large pediatric urological or surgical organization. We assessed the variability in management of UDT among pediatric urologists and pediatric surgeons at a single tertiary pediatric referral centre before publication of major guidelines.

Methods

We performed a retrospective review of the electronic records of patients who underwent primary unilateral or bilateral orchidopexy at our centre between January 2012 and January 2014.

Results

A total of 488 patients (616 testes) were identified, of whom 405 (83.0%) and 83 (17.0%) were managed by pediatric urologists and pediatric surgeons, respectively. There was no difference in baseline characteristics, including age seen in clinic or at surgery, testis location/palpability and availability of preoperative ultrasonograms, of patients seen by the 2 groups. Pediatric surgeons ordered preoperative ultrasonography more often than pediatric urologists (25.3% v. 3.7%, p < 0.001). With palpable UDTs, although both groups used open approaches, pediatric urologists preferred a scrotal approach (56.9%), and pediatric surgeons approached most testes inguinally (98.8%). With nonpalpable UDTs, laparoscopic approaches were preferred by both groups; however, pediatric urologists used a 2-stage Fowler–Stephens approach more often than pediatric surgeons (48.4% v. 15.8%, p < 0.001).

Conclusion

There was wide variation in the management of primary UDT between pediatric urologists and pediatric surgeons before the publication of guidelines. The most prominent difference between the 2 groups was in the ordering of preoperative ultrasonography. Future assessment of change in practice patterns may elucidate whether guidelines are an effective tool for standardization of practice.

Stone growth patterns and risk for surgery among children presenting with hypercalciuria, hypocitraturia and cystinuria as underlying metabolic causes of urolithiasis

INTRODUCTION

Hypercalciuria, hypocitraturia and cystinuria are the most common underlying metabolic stone abnormalities in children. The present study compared stone growth patterns, stone burden, and the risk of stone-related surgery among these underlying metabolic conditions.

METHODS

A retrospective cohort of 356 children with renal stones, followed from 2000 to 2015, was studied. Differences among metabolic groups were determined using Kruskal-Wallis test; the Scheffé-test was used for multiple comparisons to determine differences among single groups. Independent sample t-test was used when adequate, given the sample size, and Chi-squared test was used for categorical variables. Stone growth rates were calculated as differences in diameter divided by time elapsed between U/Ss (mm/year). Logistic regression was performed to assess the effect of initial stone size on the likelihood of surgery.

RESULTS

Median stone size at presentation was significantly different among groups, with cystinuria being the group with the largest proportion of stones >10 mm, while patients with stones <5 mm were likely to have a normal metabolic workup (P < 0.05). Stones with a higher growth rate were found in the operative group, while slower growing stones were mostly managed conservatively (3.4 mm/year vs 0.8 mm/year, respectively; P = 0.014). However, stone growth rates were not significantly different among metabolic groups. On the other hand, the rate of new stone formation in cystinuric patients at their first follow-up was 30.4%, which was significantly higher than in patients with hypercalciuria (16.3%) or with a normal metabolic workup (17.2%; P < 0.05). Compared with stones <5 mm, stones measuring 5-10 mm were more than four times more likely to result in surgery, whereas the likelihood of surgery for 10-20 mm or >20 mm stones was almost 16 or 34 times, respectively (P < 0.001).

CONCLUSIONS

It is believed that this is the first study to evaluate stone growth patterns, stone burden and surgical risk among children with hypercalciuria, hypocitraturia and cystinuria. Cystinuric patients presented with larger stones at the time of diagnosis, higher new stone formation rates, and were at higher risk of surgery. While no significant difference of growth rate was found among metabolic groups, stones with a higher growth rate were significantly more likely to result in surgical treatment than slower growing stones. Initial stone size, location of largest stone, previous urinary tract infection, and patient's metabolic type significantly influenced the likelihood of a surgical intervention. Better understanding of the natural history ultimately helps surgeons and clinicians defining prognosis, treatment, and prevention plans for pediatric urolithiasis.

Flexible cystoscope retrieval of detached resectoscope sheath beak

Surveillance cystoscopy for bladder cancer following transurethral resection of the prostate (TURP) can have unexpected consequences, such as the detachment of the resectoscope beak. This is an infrequent event, with few published or standard techniques for its retrieval. These techniques range from the use of forceps, as Grainger et al described in the first published case report on resectoscope sheath extraction, to the use a holmium YAG laser with a 200 μm fiber to fragment the 26 French (Fr) resectoscope sheath in the patient’s bladder and other laser-based techniques. We hypothesize that resectoscope beak extraction can be achieved efficiently and safely using a flexible cystoscope in the absence of a laser apparatus and with better postoperative results than rigid resectoscope or forceps for extraction.

Developing a program for pediatric urological care in the community

The growth of large metropolitan areas across Canada has fostered the need to provide tertiary care to patients outside of the traditional university-affiliated hospitals. Subspecialty urology care at centres of excellence in the community includes urological oncology, men’s health, community urology, and pediatric urology. The two of us have developed such centres of excellence in pediatric urology in the communitysettings of Mississauga, ON, and Victoria, BC. This article highlights personal experiences in developing these programs and the lessons learned. It is hoped that this can help guide similar undertakings by others to develop centres of excellence in subspecialty urology care so as to bring care closer to patients’ homes.

Outcome Analysis of Asymptomatic Lower Pole Stones in Children

PURPOSE

Lower pole renal stones in children usually present incidentally. To our knowledge frequency and need for intervention are unknown. We evaluated the outcomes of asymptomatic, incidentally found lower pole renal stones in children.

MATERIALS AND METHODS

We retrospectively reviewed the charts and renal ultrasounds of children with lower pole stones seen during a period of 14 years. The unpaired t-test was used to determine factors that might predict the need for stone intervention, including size, growth rate, type of stone and underlying metabolic disease. The success rate of nonoperative management, defined by spontaneous passage or lack of growth in the absence of symptoms, was calculated.

RESULTS

A total of 224 children were found to have lower pole stones. Mean ± SD age at presentation was 95.2 ± 65.3 months. Of the patients 120 (53.6%) spontaneously passed stones. Of the stones 25% remained asymptomatic and did not grow with time. Intervention was performed in 48 children (21.4%). Stones originally managed conservatively that later required intervention were significantly larger at baseline than stones that did not require intervention through the end of followup (median 7 vs 5 mm, p <0.001) and those that grew with time (median stone size 8 mm at surgical intervention, p = 0.01).

CONCLUSIONS

Our data suggest that asymptomatic lower pole renal stones can be followed conservatively. Of the calculi 78.6% passed spontaneously or remained asymptomatic and did not grow. Median initial size greater than 7 mm and stone growth with time were significant risk factors that predicted the need for intervention.

Should the presence of congenital para-ureteral diverticulum affect the management of vesicoureteral reflux?

PURPOSE

The presence of congenital para-ureteral diverticulum (PUD) has been presumed to lower the resolution rate of vesicoureteral reflux (VUR). PUD is considered an important cause of distortion of the vesicoureteral junction and persistence of VUR. Early surgery has been recommended based on this assumption. However, the scientific evidence supporting this approach is weak. We have been managing this group of patients more conservatively in the last 7 to 8 years on the premise that the presence of PUD is not per se an indication for surgery. To test this hypothesis, we performed a retrospective cohort study to compare the outcome of VUR in children with and without PUD.

MATERIALS AND METHODS

We identified 141 consecutive patients with VUR associated with PUD between 1990 and 2004. Of the patients 57 with duplication, ureterocele, neurogenic bladder or outlet obstruction were excluded from study. Median age of the remaining 84 patients at diagnosis was 2.9 years and 56 (69%) were males. Reflux was bilateral in 4 patients, and low (I to II), intermediate (III) and high (IV to V) grade in 39%, 35% and 26%, respectively. Followup was 3 to 168 months (median 47). The outcome was compared to a control group of 95 patients (150 units) with primary VUR and no PUD. The baseline parameters and followup were comparable in both groups.

RESULTS

Overall, VUR resolved in 43%, persisted in 27% and was surgically corrected in 30% of the units with PUD. In the 25 patients (26 units) who underwent surgical intervention breakthrough urinary tract infection or new renal scars were the indication in only 5. The remainder were operated on because of persistent VUR and the presence of PUD, mainly before 1997. The incidence of breakthrough urinary tract infection or new renal scar was similar in the controls (6% in PUD group vs 10% in controls, p = 0.7). The resolution rate was 60% for low grade, 39% for intermediate grade and 22% for high grade VUR. These figures were not significantly different from those of the control group in which the resolution rates were 52%, 28% and 33% for comparable grades (p = 0.9). Kaplan-Meier analysis and log rank test did not show any difference in resolution of VUR in the 2 groups (p = 0.84). Multivariate analysis identified grade as the only variable affecting resolution (p = 0.028). The size of PUD did not affect the likelihood of resolution.

CONCLUSIONS

The outcome of VUR is similar in children with or without PUD. Therefore, treatment of these patients should not differ. Surgery should be reserved for patients with breakthrough infection or renal scar progression.

VESICOURETERAL REFLUX AND COMPLETE URETERAL DUPLICATION. CONSERVATIVE OR SURGICAL MANAGEMENT?

PURPOSE

The management of vesicoureteral reflux (VUR) in a duplicated collecting system (DS) is controversial. Available literature is sparse and it does not assess all co-factors. We compared the outcome of VUR in DS cases with VUR in single system (SS) cases, given similar clinical management in the 2 groups.

MATERIALS AND METHODS

A retrospective cohort study was done to compare the outcome of VUR in 35 children (44 units) with a DS and in 95 (150 units) with an SS. Patients with secondary reflux, incomplete duplication and ureterocele were excluded. Two groups were similar in terms of prognostic factors. Mean followup in the DS and SS groups was 43 and 48 months, respectively. Outcomes of interest were spontaneous resolution or uncomplicated persistence vs surgical correction. The same criteria were used to intervene surgically in the 2 groups.

RESULTS

In the DS group 24 of 35 patients (69%) underwent surgery compared with 25 of 95 (25%) in the SS group. Multivariate analysis showed an association between surgery due to complications and the presence of DS (p = 0.0001). Higher grade and female gender were independent predictors (p = 0.02 and 0.0007, respectively). The likelihood of undergoing surgery was the same for low grade VUR (I and II) in the DS and SS groups (p = 0.16). No resolution was seen in the duplex group with severe VUR at a mean followup of 42 months.

CONCLUSIONS

Low grade VUR in DS cases has an outcome similar to that of VUR in SS cases. Females with moderate or high grade VUR and a DS should be treated differently because they present more often with complications.

A NOVEL APPROACH TO SKIN COVERAGE FOR EPISPADIAS REPAIR

PURPOSE

Current techniques for epispadias repair have resulted in significant improvement in the reconstruction of the urethra, corpora and glans. The final challenging step is to enhance the cosmetic result by accomplishing skin coverage for the penis and subpubic area, creating a penopubic and penoscrotal angle without dorsal suture lines, and avoiding future dorsal tethering of the penis as a result of scar contraction. We report a novel technique for penile skin coverage in the patient with epispadias that results in a superior cosmetic outcome.

MATERIALS AND METHODS

The technique involves creation of 2 flaps-a ventral preputial transverse island flap rotated dorsally to cover the dorsal aspect of the penile shaft, and an advancement flap from the patch of skin present between the penis and scrotum in epispadias, which is advanced distally to cover the ventral aspect of the penis. The 2 flaps are sewn to each other with 2 lateral suture lines. Thus, the dorsal and ventral aspects of the penis are covered with intact skin devoid of suture lines.

RESULTS

This technique was used in 8 males 2 days to 15 years old. The epispadias was part of exstrophy in 5 patients and an isolated defect in 3. Both flaps healed well in 7 of 8 patients. In 1 exstrophy case a segment of the transverse island flap became ischemic and was discarded intraoperatively. Dorsal skin coverage in this patient was achieved using a laterally based flap from the inguinal area, which healed without problem. Followup was 6 to 33 months. No patient had development of skin tethering, curvature or recurrence of the dorsal chordee. The cosmetic appearance of the penis was subjectively superior to that of boys who underwent skin closure using reverse Byars flaps.

CONCLUSIONS

The cosmetic appearance of the penis using this novel technique is superior because of the absence of the dorsal scar that may cause chordee, the development of penopubic and penoscrotal angles, which gives the penis a more normal appearance, and the absence of the redundant patch of skin between the shaft of the penis and the scrotum.

Outcome of small residual stone fragments following shock wave lithotripsy in children

PURPOSE

We evaluate the outcome of small residual stone fragments (RF) following extra-corporeal shock wave lithotripsy (ESWL, Dornier Medical Systems, Inc., Marietta, Georgia) in children.

MATERIALS AND METHODS

The medical records of 39 boys and 44 girls (88 renal units) with urolithiasis who underwent ESWL were reviewed. Median patient age was 7 years. Average stone burden was 14 mm. Mean followup was 46 months. After the first ESWL 40 of the 88 (46%) renal units became stone-free and 18 (20%) had RF 5 mm or less. The remaining 30 (34%) units required further treatment using ESWL or ancillary surgical procedures that rendered 12 of them stone-free and 8 with RF. The 26 renal units with RF constitute our study subjects. Adverse outcomes such as growth of RF, symptomatic episodes or calculi recurrence in stone-free cases were recorded.

RESULTS

Of the 26 renal units with RF 5 mm or less, 18 (69%) had an adverse clinical outcome (symptoms or RF growth) and 8 (31%) patients were asymptomatic and had no stone growth. Patients with RF had a significant increase in adverse clinical outcome compared to stone-free subjects, with an odds ratio of 3.9 (95% CI 1.5-9.6). The presence of metabolic disorders was associated with RF growth (odds ratio 11.4, 95% CI 1.5-79).

CONCLUSIONS

Small RF after ESWL is clinically significant in children and increase the chance of adverse clinical outcome. These patients require close followup, particularly those with identifiable predisposing disorders.

Retroperitoneal-Assisted Laparoscopic Pyeloplasty in Children: Initial Experience

PURPOSE

To demonstrate a novel application of laparoscopy to assist in the correction of ureteropelvic junction (UPJ) obstruction.

PATIENTS AND METHODS

A retroperitoneal space is created, and the UPJ is identified and dissected from the surrounding tissue with a 1 x 10-mm 0 degrees telescope and 2 x 5-mm endoscopic instruments. Using a 5-0 Prolene stay suture, the UPJ is brought up through the 10-mm trocar site to the skin level, and the pyeloplasty is performed ex vivo over a double-J stent with loop magnification. Between July 2002 and March 2003, nine male and two female patients with UPJ obstruction underwent a pyeloplasty using this retroperitoneal-assisted laparoscopic pyeloplasty (RALP). The operative time, hospital stay, pain management, and follow-up radiologic studies were reviewed.

RESULTS

In nine patients, RALP (bilateral in one patient) was performed (nine on the left side and one on the right). In the remaining two patients, mobilization of the UPJ was inadequate, and open conversion was performed. The average RALP operative time was 160 minutes (range 121-193 minutes). Postoperative pain management was optimal using oral codeine in eight patients, while one patient (RALP and pyelolithotomy) received parenteral analgesic postoperatively. The average length of stay in the hospital was 2 days (range 1-3 days). Follow-up (5-14 months) radiologic studies after stent removal showed improvement in the hydronephrosis in all except one patient. Furosemide renal scan at 3 to 6 months postoperatively was done in all patients and showed no obstruction.

CONCLUSION

We consider RALP as the technique of choice for surgeons who want to increase their reconstructive laparoscopic skills. It provides an additional technique when skilled laparoscopists are faced with technically difficult pyeloplasties.

Effect of adult microsurgical varicocelectomy on testicular volume

OBJECTIVES

To re-examine the potential influence of varicocelectomy on testicular volume using scrotal ultrasonography, because it has been reported that total testicular volume (assessed by physical examination) increases after adult varicocele ligation.

METHODS

A retrospective review of the testicular volume and semen parameters of 61 men who underwent microsurgical varicocelectomy between 1996 and 1998 was performed. Ultrasound-derived testicular volumes and total motile sperm counts were compared before varicocelectomy and at a mean of 7.2 months postoperatively.

RESULTS

Bilateral varicocelectomy was performed in 22 men; 39 men underwent a left-sided procedure only. Overall, no significant change was found in the mean total testicular volume after varicocelectomy compared with preoperatively (24.0 versus 23.9 mL, respectively; P = 0.74). Similarly, the testicular volumes did not change significantly after left or bilateral varicocelectomy (P >0.05). Overall, the mean total motile sperm count increased significantly after varicocelectomy (17. 9 to 25.4, P = 0.05).

CONCLUSIONS

This was the first study to examine the effect of adult varicocelectomy on testicular volume using ultrasound-derived measurements of volume. Unlike previous findings, our data suggest that although adult varicocelectomy improves semen quality in most infertile men, it does not result in a significant increase in testicular volume.

Conserved tyrosines in the alpha subunit of the nicotinic acetylcholine receptor stabilize quaternary ammonium groups of agonists and curariform antagonists

Studies with site-directed labeling reagents have identified residues near the ligand binding pocket of the nicotinic acetylcholine receptor. Among these residues are three conserved tyrosines, Tyr-93, Tyr-190, and Tyr-198 of the alpha subunit. Previous studies combined mutagenesis, expression in Xenopus oocytes, and dose-response analysis to examine contributions of these tyrosines to agonist affinity. In this study, we prepared a series of mutants at each position, expressed them in 293 HEK cells, and studied binding of agonists and antagonists to mutant receptors on intact cells. We show that all three tyrosines contribute to binding of agonists, and that each tyrosine contributes roughly equally to the binding energy. Although the contributions are roughly equivalent, the nature of the contribution is not equivalent at each position. For Tyr-93 and Tyr-190 the aromatic hydroxyl is essential, whereas for Tyr-198 aromaticity of the side chain is essential. Nearly identical results were obtained for the elementary quaternary ligand tetramethylammonium, indicating that these tyrosines contribute to stabilization of the quaternary ammonium portion of agonist. Tyr-190 and Tyr-198 also contribute to binding of the competitive antagonist dimethyl-d-tubocurarine; the side chain specificity for binding supports tyrosine interactions with one of two quaternary ammonium groups in dimethyl-d-tubocurarine. Y190F, in addition to altering binding affinity, also affects the equilibrium between activatable and desensitized receptor states.