Population Management Approach to Kidney Stone Care Improves Patient Compliance to Preventive Measures and Reduces Resource Utilization in Patients at High Risk for Stone Recurrence.

INTRODUCTION: Nephrolithiasis is a chronic condition with 5 to 10-year recurrence rates as high as 50%. Stone recurrence can be reduced by implementing American Urological Association kidney stone medical management guidelines, which recommend additional metabolic testing for high risk, recurrent and interested first-time stone formers. However, clinician adherence to guidelines is variable, and patient compliance with preventive evaluations is low. We evaluated our kidney stone population management program's role in patient compliance with completing American Urological Association metabolic studies. We assessed the program's impact on office encounters, operating room procedures and emergency department visits for known high risk kidney stone patients. METHODS: A retrospective review of electronic medical records between 2009 and 2017 identified 4,029 kidney stone patients. A total of 873 patients were at high risk for kidney stone recurrence. In 2013, we established a population management program in which high risk patients were referred and followed by a nurse case manager. Patients were contacted by email or telephone if metabolic serum and urine collections were incomplete. Office, operating room and emergency department visits were compared before and after the program's implementation. RESULTS: Metabolic evaluation orders increased from 17% to 35% in our institution's urology department. Patient compliance with recommended studies improved from <10% to 82%, and reductions in office visits by 48%, surgical procedures by 38% and emergency department encounters by 40% were observed. CONCLUSIONS: Our program improved patient compliance with American Urological Association recommended studies for high risk kidney stone patients. Reductions in stone events may have been due to our program but require further study in the future.

Aqueous extract of Costus arabicus inhibits calcium oxalate crystal growth and adhesion to renal epithelial cells.

Costus arabicus L. (C. arabicus) is a plant used in Brazilian folk medicine to treat urolithiasis; however, its mechanism of action is unclear. The interaction between calcium oxalate (CaOx) crystals and the renal epithelium is important in calculogenesis, and compounds that modulate this process represent candidate therapeutic agents for stone prevention. Therefore, we assessed the inhibitory activity of C. arabicus on CaOx crystallization and the interaction of CaOx crystals with the renal epithelium. A seeded CaOx monohydrate (COM) crystallization system was used to study the effect of C. arabicus on crystal growth. Madin Darby canine kidney (MDCK) cells were used to study [(14)C] COM crystal adhesion in the presence and absence of an aqueous extract of C. arabicus. Cytotoxicity was assessed using a tetrazolium (MTS) cell proliferation assay. Aqueous extracts of C. arabicus decreased crystal growth in a concentration-dependent fashion. Precoating crystals with C. arabicus extract prevented their adhesion to MDCK cells, while pretreating cells did not show any effect. The extract was non-cytotoxic in concentrations of at least 1 mg/ml, which is likely above concentrations achievable in the urine following oral ingestion and excretion. No inhibitory activity was found in hexane, methyl chloride, n-butanol and ethyl acetate fractions of an ethanol extract of the herb. An aqueous extract of C. arabicus may disrupt calculogenesis by interacting with CaOx crystal surfaces. Activity was present in the aqueous extract; therefore, this agent may be bioavailable when administered orally. Fractionation results suggest that the active agent might be a polar polysaccharide. Further identification and characterization along these lines may be warranted.

Secondarily infected nonstruvite urolithiasis: a prospective evaluation.

OBJECTIVE: To characterize patients who form nonstruvite stones associated with infection (secondarily infected calculi), and to define the bacteria associated with these. MATERIALS AND METHODS: Patients undergoing percutaneous nephrolithotomy were prospectively recruited. Medical records were reviewed, and stones were analyzed using micro computed tomography and infrared spectroscopy. A fragment of each stone was sent for bacterial culture. Patients were categorized by stone culture results (SC ±) and the presence of struvite (ST ±). The Fisher exact test was used for comparison of proportion. Sterility of intraoperative SC was established with independently collected controls. RESULTS: In total, 125 patients were enrolled: 24 SC+/ST-, 19 SC+/ST+, and 82 SC-/ST-. Proportions of patients with prior urologic surgery, diabetes, and immunodeficiency were similar between groups. Patients with neurogenic bladder were more likely to have SC+/ST+ stones or SC+/ST- stones than SC-/ST- stones (26% vs 8% vs 0%, respectively; P <.01). Among patients with metabolic evaluations, hypocitraturia was found in 31.6% (6 of 19) SC+/ST- patients, 46.7% (7 of 15) SC+/ST+ patients, and 26.0% (19 of 73) of SC-/ST- patients (P = .28). Approximately 40% of cultured organisms in the secondarily infected calculi possessed urease and another 40% citrate lyase activities. CONCLUSION: Secondarily infected stones were detected in approximately 20% of this surgical cohort and may be more common than previously appreciated. Neurogenic bladder appeared to predispose patients to either struvite or secondarily infected stones. The role of bacterial infection in stone formation is unclear but may include alteration of urinary components, acting as a nidus for crystallization, or inducing inflammation.

Long-term device outcomes of artificial urinary sphincter reimplantation following prior explantation for erosion or infection.

PURPOSE: We evaluated clinical outcomes in patients treated with artificial urinary sphincter reimplantation after artificial urinary sphincter explantation for erosion or infection. MATERIALS AND METHODS: We identified 704 consecutive artificial urinary sphincter implantation procedures performed at our institution from 1998 to 2012, including 497 (71%) as primary implantation and 138 (20%) as revision surgery for device malfunction. A total of 69 patients (10%) had undergone at least 1 prior artificial urinary sphincter explantation secondary to urethral erosion and/or device infection, of whom 36 (52%) were treated with 2 to 5 prior reimplantation procedures. Patient followup was performed through office examination, or written or telephone correspondence. RESULTS: Patients treated with artificial urinary sphincter reimplantation had a median age of 78 years (IQR 72, 80) and a median followup of 34 months (IQR 5, 61). Artificial urinary sphincter reimplantation was done a median of 9 months (IQR 6, 13) after explantation. Patients treated with reimplantation after erosion or infection were more likely to require repeat explantation than those with primary implantation (13 of 69 or 19% vs 32 of 497 or 6.4%, p = 0.002). However, when evaluating repeat procedures, the 5-year device survival rate after reimplantation due to erosion or infection vs primary implantation was 68% vs 76% (p = 0.38). CONCLUSIONS: Our findings suggest that artificial urinary sphincter reimplantation after explantation for urethral erosion and/or device infection is associated with an increased rate of recurrent erosion/infection requiring repeat explantation. However, in appropriately selected and counseled patients clinically acceptable long-term device use can be achieved.

Acute bilateral ureteral obstruction secondary to guaifenesin toxicity.

Several medications or their metabolites have been associated with urolithiasis, although overall they remain an infrequent cause of urolithiasis. Guaifenesin stones were originally reported as complexed with ephedrine, and subsequent reports have demonstrated pure guaifenesin stones, occurring after long term abuse. We report a case of a 23-year-old male who ingested a large, one time dose of guaifenesin, resulting in acute bilateral ureteral obstruction, which, to our knowledge, is the first such reported case in the literature.

Advances in tubeless percutaneous nephrolithotomy and patient selection: an update.

Percutaneous nephrolithotomy (PCNL) is the gold standard for the treatment of large renal calculi. Recently, modifications to the standard PCNL with nephrostomy tube placement have evolved, most notably the introduction of tubeless PCNL. Tubeless PCNL appears to decrease postoperative discomfort and shorten hospital stays, without increasing complication rates in the appropriately selected patient population. Urologists have attempted to expand the role of tubeless PCNL in more complex clinical scenarios, including pediatric and geriatric patients, and in stones complicated by multiple access tracts, renal anomalies or previous renal surgery. In an attempt to further improve outcomes following tubeless PCNL, adjunct interventions such as the use of hemostatic agents along the percutaneous access tract and local tract anesthetic have also been evaluated. We report the most recent published data over the past year, reviewing the employment and efficacy of tubeless PCNL, and discuss the selection of appropriate patients for this modified procedure.

The impact of an antibiotic coating on the artificial urinary sphincter infection rate.

PURPOSE: In April 2008 InhibiZone® antibiotic coated artificial urinary sphincters were introduced. The antibiotic coating significantly increased the cost of the device by an average of $1,300 per artificial urinary sphincter. To our knowledge, no clinical data to date support the theory that this antibiotic coating decreases the risk of artificial urinary sphincter infection. Therefore, we compared infection rates in our cases before and after the introduction of InhibiZone coated artificial urinary sphincters to determine whether the coating decreased the device infection rate. MATERIALS AND METHODS: We retrospectively reviewed the records of 426 consecutive patients in whom an artificial urinary sphincter was implanted by a single surgeon from January 2005 to June 2012. Patients were divided equally into 213 consecutive males who received an artificial urinary sphincter without the antibiotic coating from January 2005 to March 2008 and 213 consecutive males implanted with the antibiotic coated artificial urinary sphincter from April 2008 to June 2012. Demographics and infection rates were compared. RESULTS: Patient mean age, associated comorbidities and complexity were almost identical in the groups with and without the antibiotic coating, and infection rates were identical at 7 patients (3.3%) per group (p = 0.99). In the more complex patient subgroup with revision the antibiotic coating did not impact the infection rate. Infection developed in 2 of 50 patients (5%) with the antibiotic coated device and in 3 of 38 (6%) with the uncoated device (p = 0.42). CONCLUSIONS: The InhibiZone coating of the artificial urinary sphincters did not alter the infection rate in our study. The added cost of the antibiotic coated artificial urinary sphincters (total of approximately $276,000 more for all 213 coated devices) was of no benefit in our series. Based on this assessment, we will transition to using artificial urinary sphincters without InhibiZone in our practice.

Shock wave lithotripsy and diabetes mellitus: a population-based cohort study.

OBJECTIVE: To determine if shock wave lithotripsy (SWL) is associated with diabetes mellitus (DM) in a community setting. The pancreas is vulnerable to injury at SWL as evidenced by case studies; thus, concern exists for the development of DM after SWL. METHODS: The Rochester Epidemiologic Project was used to identify all Olmsted County, Minnesota residents diagnosed with urolithiasis from 1985 to 2008. New-onset DM was identified by diagnostic codes and treatment with SWL by surgical codes. Cox proportional hazards models were used to determine the risk of DM after SWL therapy. RESULTS: A total of 5287 incident cases of stone formation without pre-existing DM and with ≥3 months of follow-up. After an average follow-up of 8.7 years, 423 patients (8%) were treated with SWL and new-onset DM had developed in 743 (12%). The diagnosis of DM followed SWL in 77 patients. However, no association was evident between SWL and the development of DM before (hazard ratio 0.98, 95% confidence interval 0.76-1.26) or after (hazard ratio 0.92, 95% confidence interval 0.71-1.18) SWL, controlling for age, sex, and obesity. CONCLUSION: In the present large, population-based cohort, the long-term risk of developing DM was not increased in persons who underwent SWL to treat their kidney stones.