Daniel Olvera-Posada

Risk Factors for Postoperative Complications of Percutaneous Nephrolithotomy at a Tertiary Referral Center

PURPOSE We sought to describe and evaluate the complications related to percutaneous nephrolithotomy and identify risk factors of morbidity according to the modified Clavien scoring system. We also sought to specify which perioperative factors are associated with minor and major complications. MATERIALS AND METHODS We retrospectively analyzed data on patients who underwent percutaneous nephrolithotomy from 1990 to 2013. Descriptive statistics were used to analyze patient characteristics, medical comorbidities and perioperative features. Complications were categorized according to the Clavien score for percutaneous nephrolithotomy. The Mann-Whitney and Fisher exact tests were used as appropriate. Logistic regression analysis was performed to look for prognostic factors associated with major complications. RESULTS A total of 2,318 surgeries were evaluated. Mean age of the population was 53.7 years. The stone-free rate at hospital discharge was 81.6%. The overall complication rate was 18.3%. Two deaths occurred. Patients with any postoperative complications were older, had more comorbidities, were more likely to have staghorn calculi and had longer operative time and hospital stay on univariate analysis (p<0.05). Age 55 years or older and upper pole access were independent predictors of major complications on multivariate analysis. Other factors such as a history of urinary tract infections, body mass index, stone composition, previous percutaneous nephrolithotomy and multiple tracts were not associated with a major complication. CONCLUSIONS At our center percutaneous nephrolithotomy is an excellent option for complex kidney stone management with a low overall complication rate. Older patient age and upper pole access are significantly associated with an increased risk of a major complication.

Emphysematous Pyelonephritis: Multicenter Clinical and Therapeutic Experience in Mexico

OBJECTIVE To analyze the outcomes of emphysematous pyelonephritis (EPN), the impact of different treatment modalities, and to determine risk factors associated with mortality. METHODS We retrospectively reviewed cases of EPN from 3 tertiary care institutions in Mexico. The diagnosis was confirmed with computed tomographic scan. Treatment was classified as follows: medical management (MM), minimally invasive, and surgical. Demographic, clinical, biochemical, and radiological characteristics were assessed and compared between survivors and nonsurvivors. Comparison was assessed using 1-way analysis of variance and chi-square. Univariate and multivariate logistic regression analyses were performed to determine prognostic factors. Main end point was mortality. RESULTS A total of 62 patients were included (49 women and 13 men), with a mean age of 53.9 years. The most common comorbidities were diabetes (69.3%) and hypertension (40.3%). Escherichia coli was the most common isolated microorganism (62.7%). MM was provided to 24.2%, minimally invasive treatment to 51.6%, open drainage to 19.3%, and emergency nephrectomy to 4.8%. Overall mortality was 14.5% and was similar among different treatment modalities (P=.06). Survivors were younger (P=.004), had lower creatinine (P=.002), and better estimated glomerular filtration rate (P=.007). In univariate analysis, age (P=.009), creatinine (P=.009), and need for nephrectomy (P=.03) were associated with mortality. In multivariate logistic regression analysis, creatinine (odds ratio 1.56, 95% confidence interval 1.03-2.35, P=.03) and nephrectomy (odds ratio 9.7, 95% confidence interval 1.007-93.51, P=.049) remained significant predictors of mortality. CONCLUSION EPN needs an aggressive MM and stepwise approach; nephrectomy should be the last resort of treatment. Creatinine level and need for nephrectomy are the strongest predictors of mortality according our analysis.

Natural History of Residual Fragments After Percutaneous Nephrolithotomy: Evaluation of Factors Related to Clinical Events and Intervention

OBJECTIVE To determine the natural history of residual fragments (RF) after percutaneous nephrolithotomy in long-term patient follow-up and to identify possible predictive factors for future intervention. MATERIALS AND METHODS We assessed all patients from 2006 to 2013 with postoperative computed tomography scan revealing RF, who did not undergo second-look nephroscopy or immediate ancillary procedures, and with at least 12 months of clinical follow-up. We evaluated factors associated with clinical, radiological, and surgical outcomes. Kaplan-Meier curves were used to calculate the proportion of asymptomatic and treatment-free patients during follow-up. RESULTS From 781 percutaneous nephrolithotomies performed, 202 patients underwent postoperative computed tomography scan and 44 patients with residual stones were included in the analysis. Mean follow-up was 57.9 months. A total of 24 patients (54.5%) developed at least 1 clinical outcome, and 32 (72.7%) patients had a surgical intervention. Only 4 patients had radiological evidence of stone passage. Multivariate analysis found that RF >4 mm and struvite or apatite stones were significant predictors for surgical intervention. The 5-year estimated probability to remain intervention free was 29%. CONCLUSION Despite the size of the RF, the vast majority of patients required an intervention during long-term follow-up. We identified that RFs of diameter >4 mm associate with the need for a surgical therapy, but the rate of clinical events was not affected by the size or location of the stones. Struvite or apatite composition stones had an increased risk of intervention during follow-up. Spontaneous passage was an uncommon event in this cohort.

Erectile Dysfunction Among HIV Patients Undergoing Highly Active Antiretroviral Therapy: Dyslipidemia as a Main Risk Factor

Objective To assess the prevalence and risk factors of erectile dysfunction (ED) in HIV patients from the HIV clinic of a tertiary referral center in Mexico City. Design Prevalence was obtained from cross-sectional studies, and the International Index of Erectile Function (IIEF), a standardized method, was used to assess ED. Methods A cross-sectional study was performed in the HIV clinic. Participants completed the IIEF to allow ED assessment. Information on demographics, clinical and HIV-related variables was retrieved from their medical records. Results One hundred and nine patients were included, with a mean age of 39.9 ± 8.8 years. ED was present in 65.1% of the individuals. Patients had been diagnosed with HIV for a mean of 92.7 ± 70.3 months and had undergone a mean 56.4 ± 45.5 months of HAART. The only variable associated with ED in the univariate analysis was dyslipidemia, and this association was also found in the multivariate analysis (P = 0.01). Conclusions ED is highly prevalent in HIV patients. Dyslipidemia should be considered as a risk factor for ED in HIV patients. Romero-Velez G, Lisker-Cervantes A, Villeda-Sandoval CI, Sotomayor de Zavaleta M, Olvera-Posada D, Sierra-Madero JG, Arreguin-Camacho LO, and Castillejos-Molina RA. Erectile dysfunction among HIV patients undergoing highly active antiretroviral therapy: Dyslipidemia as a main risk factor. Sex Med 2014;2:24–30.

KIM-1 Is a Potential Urinary Biomarker of Obstruction: Results from a Prospective Cohort Study.

INTRODUCTION Partial or complete obstruction of the urinary tract is a common and challenging urological condition that may occur in patients of any age. Serum creatinine is the most commonly used method to evaluate global renal function, although it has low sensitivity for early changes in the glomerular filtration rate or unilateral renal pathology. Hence, finding another measurable parameter that reflects the adaptation of the renal physiology to these circumstances is important. Several recent studies have assessed the use of new biomarkers of acute kidney injury (AKI), but the information among patients with stone disease and those with obstructive uropathy is limited. MATERIAL AND METHODS A prospective cohort study was conducted to determine the urinary levels of kidney injury molecule-1 (KIM-1), Total and Monomeric neutrophil gelatinase-associated lipocalin (NGAL) in patients with hydronephrosis secondary to renal stone disease, congenital ureteropelvic junction obstruction or ureteral stricture. Comparison between patients with hydronephrosis and no hydronephrosis was carried out along with correlation analysis to detect factors associated with biomarker expression. RESULTS Urinary levels of KIM-1 significantly decreased after hydronephrosis treatment in patients with unilateral obstruction (1.19 ng/mL vs 0.76 ng/mL creatinine, p = 0.002), additionally KIM-1 was significantly higher in patients with hydronephrosis compared to stone disease patients without radiological evidence of obstruction (1.19 vs 0.64, p = 0.006). Total and Monomeric NGAL showed a moderate correlation with the presence of leukocyturia. We found that a KIM-1 value of 0.735 ng/mg creatinine had a sensitivity of 75% and specificity of 67% to predict the presence of hydronephrosis in preoperative studies (95% CI 0.58-0.87, p = 0.006). CONCLUSION Our results show that KIM-1 is a promising biomarker of subclinical AKI associated with hydronephrosis in urological patients. NGAL values were influenced by the presence of leukocyturia, limiting its usefulness in this population.

Combining Mean and Standard Deviation of Hounsfield Unit Measurements from Preoperative CT Allows More Accurate Prediction of Urinary Stone Composition Than Mean Hounsfield Units Alone

INTRODUCTION AND OBJECTIVES The mineral composition of a urinary stone may influence its surgical and medical treatment. Previous attempts at identifying stone composition based on mean Hounsfield Units (HUm) have had varied success. We aimed to evaluate the additional use of standard deviation of HU (HUsd) to more accurately predict stone composition. METHODS We identified patients from two centers who had undergone urinary stone treatment between 2006 and 2013 and had mineral stone analysis and a computed tomography (CT) available. HUm and HUsd of the stones were compared with ANOVA. Receiver operative characteristic analysis with area under the curve (AUC), Youden index, and likelihood ratio calculations were performed. RESULTS Data were available for 466 patients. The major components were calcium oxalate monohydrate (COM), uric acid, hydroxyapatite, struvite, brushite, cystine, and CO dihydrate (COD) in 41.4%, 19.3%, 12.4%, 7.5%, 5.8%, 5.4%, and 4.7% of patients, respectively. The HUm of UA and Br was significantly lower and higher than the HUm of any other stone type, respectively. HUm and HUsd were most accurate in predicting uric acid with an AUC of 0.969 and 0.851, respectively. The combined use of HUm and HUsd resulted in increased positive predictive value and higher likelihood ratios for identifying a stones mineral composition for all stone types but COM. CONCLUSIONS To the best of our knowledge, this is the first report of CT data aiding in the prediction of brushite stone composition. Both HUm and HUsd can help predict stone composition and their combined use results in higher likelihood ratios influencing probability.

The Impact of Multiple Prostate Biopsies on Risk for Major Complications Following Radical Prostatectomy: a Population-Based Cohort Study.

OBJECTIVE To evaluate the impact of multiple transrectal ultrasound-guided prostate biopsies (TRUS-Bx) before radical prostatectomy (RP) on surgical outcomes. MATERIALS AND METHODS Administrative databases were used to identify all patients who had a RP performed in the province of Ontario from April 1, 2002, to March 31, 2013. TRUS-Bx prior to RP were identified and patients were categorized as having one or more than one prior TRUS-Bx. The primary end point was a composite index of serious surgical complications. Secondary outcomes included oncological interventions, functional-related events, and general health service-related outcomes. RESULTS Among 27,637 patients, 4780 (17.3%) had ≥2 biopsies performed before RP. The proportion of patients who experienced the composite end point was similar between those with one TRUS-Bx compared to those with ≥2 TRUS-Bx (1.05% vs 1.19%, OR 1.14, 95% CI 0.85-1.52). Patients with ≥2 biopsies were more likely to have a perioperative blood transfusion compared to patients with only 1 biopsy (15.5% vs 12.8%, OR 1.25, 95% CI 1.15-1.37), while readmission rate and 30-day mortality were similar. The need for radiotherapy and androgen deprivation therapy within the first year after RP was higher in patients with a single biopsy. Patients with multiple TRUS-Bx were more likely to require post-RP urodynamic evaluation and bladder neck contracture-related interventions but were not at increased odds of surgery for incontinence or erectile dysfunction. CONCLUSION Perioperative outcomes after RP are similar between men with single or multiple TRUS-Bx, although multiple TRUS-Bx were associated with an increased odds of perioperative blood transfusion.

Novel Methods of Determining Urinary Calculi Composition: Petrographic Thin Sectioning of Calculi and Nanoscale Flow Cytometry Urinalysis

Accurate determination of urinary stone composition has significant bearing on understanding pathophysiology, choosing treatment modalities and preventing recurrence. A need exists for improved methods to determine stone composition. Urine of 31 patients with known renal calculi was examined with nanoscale flow cytometry and the calculi collected during surgery subsequently underwent petrographic thin sectioning with polarized and fluorescent microscopy. Fluorescently labeled bisphosphonate probes (Alendronate-fluorescein/Alendronate-Cy5) were developed for nanoscale flow cytometry to enumerate nanocrystals that bound the fluorescent probes. Petrographic sections of stones were also imaged by fluorescent and polarized light microscopy with composition analysis correlated to alendronate +ve nanocrystal counts in corresponding urine samples. Urine samples from patients with Ca2+ and Mg2+ based calculi exhibited the highest alendronate +ve nanocrystal counts, ranging from 100–1000 nm in diameter. This novel urine based assay was in agreement with composition determined by petrographic thin sections with Alendronate probes. In some cases, high alendronate +ve nanocrystal counts indicated a Ca2+ or Mg2+ composition, as confirmed by petrographic analysis, overturning initial spectrophotometric diagnosis of stone composition. The combination of nanoscale flow cytometry and petrographic thin sections offer an alternative means for determining stone composition. Nanoscale flow cytometry of alendronate +ve nanocrystals alone may provide a high-throughput means of evaluating stone burden.

The Effect of Renal Cysts on the Fragmentation of Renal Stones During Shockwave Lithotripsy: A Comparative In Vitro Study

PURPOSE To assess the potential effect of simple renal cysts (SRC) on stone fragmentation during shockwave lithotripsy (SWL) in an in vitro model. MATERIALS AND METHODS The in vitro model was constructed using 10% ordnance gelatin (OG). Models were created to mimic four scenarios: Model A-with an air-filled cavity (suboptimal for stone fragmentation); model B-without a cavity (normal anatomy); model C-with a 3-cm serum filled cavity (to represent a small SRC); model D-with a 4-cm serum filled cavity (to represent a larger SRC). SWL was applied to 24 standardized phantom stones (weight of 2±0.1 g) in each model using a standardized protocol. Stone fragments were retrieved, then dried overnight at room air temperature. Fragmentation coefficient (FC) was calculated for each stone, for fragments<4 mm and <2 mm. RESULTS The OG in vitro model was robust enough for the proposed research. There was no fragmentation evident in model A as expected. The mean FC was 29.7 (±20.5) and 39.7 (±23.7) for <4 mm fragments (P=0.069) and 7.6 (±4.1) and 10.6 (±6.7) for <2 mm fragments (P=0.047), for noncystic and cystic models, respectively. The mean FC was 29.7 (±20.5), 38.8 (±26.2) and 40.7 (±21.3) for <4 mm fragments (P=0.213) and 7.6 (±4.1), 11.1 (±8) and 10.2 (±5.3) for <2 mm fragments (P=0.138), for models B, C, and D, respectively. CONCLUSION Our in vitro experiment confirms better stone fragmentation associated with SWL in the presence of adjacent SRC.

A Population Based Cohort Study of the Impact of Infectious Complications Requiring Hospitalization after Prostate Biopsy on Radical Prostatectomy Surgical Outcomes

OBJECTIVE To compare radical prostatectomy outcomes in men with and without exposure to a major infectious event within 30-days of a prior TRUS-biopsy. MATERIALS AND METHODS This retrospective cohort study included men who underwent radical prostatectomy from 2002 to 2013 in Ontario, Canada. Several linked administrative databases were used. Exposure was defined as hospitalization with evidence of a urinary tract infection or sepsis during the first 30-days after a prostate biopsy. The primary outcome was a composite of procedures indicative of a likely serious complication of radical prostectomy within the first 12 months after surgery. Secondary outcomes included oncological, functional, and hospital related events within 2 years of radical prostatectomy. RESULTS A total of 26,254 patients were included in this study and 530 (2.02%) had a post-TRUS-biopsy infection. A similar proportion of patients with and without a post-TRUS-biopsy infectious event experienced the composite primary outcome (1.7% vs 1.1%; odds ratio [OR] 1.61, 95% confidence interval [CI] 0.82-3.14; P = .16). However, exposed patients had significantly higher odds of perioperative blood transfusion (OR 1.61, 95% CI 1.30-2.00; P <.001), bladder neck contracture (OR 1.35, 95% CI 1.12-1.63; P = .002), and 30-day hospital readmission (OR 2.08, 95% CI 1.47-2.95; P <.001), and a small but significant increase in length of hospital stay (P = 0.005). No other significant differences were observed. CONCLUSION Although prior infectious events are associated with increased risk of blood transfusion, bladder neck contracture, and hospital readmission following radical prostatectomy, results from this study suggest that major surgical complications, are not adversely affected by TRUS-biopsy related infections.