Dyslipidemia and kidney stone risk.

PURPOSE: We studied the impact of dyslipidemia on 24-hour urinalysis and stone composition. MATERIALS AND METHODS: We retrospectively identified patients with nephrolithiasis who underwent 24-hour urinalysis and lipid profile evaluation within 3 months. Patients were divided into groups based on total cholesterol, high density lipoprotein, nonhigh density lipoprotein and triglycerides. The groups were compared based on demographic data, diabetes, hypertension and each component of 24-hour urinalysis and stone composition. Multivariate analysis and linear regression were performed to control for potential confounders, including age, gender, body mass index, diabetes and hypertension. RESULTS: A total of 2,442 patients with a mean age of 51.1 years were included in study. On multivariate analysis patients with high total cholesterol had significantly higher urinary potassium and calcium, those with low high density lipoprotein or high triglycerides had significantly higher urinary sodium, oxalate and uric acid with lower pH, and those with high nonhigh density lipoprotein had higher urinary sodium and uric acid. Regarding stone composition, high total cholesterol and triglycerides were significantly associated with a higher uric acid stone rate (p = 0.006 and <0.001, respectively). Linear regression showed a significant association of nonhigh density lipoprotein with higher urinary sodium (p = 0.011) and uric acid (p <0.001) as well as triglycerides and higher uric acid (p = 0.017), and lower urinary pH (p = 0.005). CONCLUSIONS: There is a link between dyslipidemia and kidney stone risk that is independent of other components of metabolic syndrome such as diabetes and obesity. Specific alterations in the patient lipid profiles may portend unique aberrations in urine physicochemistry and stone risk.

Ureteric wall thickness as a novel predictor for failed retrograde ureteric stent placement.

INTRODUCTION: We sought to identify predictors of failed retrograde ureteric stent (FRS) placement in the setting of obstructing ureteric calculi. In addition to patient- and stone-specific characteristics, we also considered computed tomography (CT) measures of ureteric wall thickness (UWT), as it has shown clinical potential in predicting outcomes of shockwave lithotripsy, ureteroscopy, and spontaneous stone passage. METHODS: We performed a retrospective, case-control study comparing patients who had successful retrograde stent (SRS) insertions with those who failed stent placement and ultimately required nephrostomy tube (NT) insertion (2013-2019). Patients were identified using administrative data from a shared electronic medical record (capturing all urology patients in our geographic area) and a prospective database capturing all institutional interventional radiology procedures. Patient demographics, as well as clinical and stone characteristics were then collected, and imaging manually reviewed. Statistical analysis was performed using univariate and multivariate logistic regression analysis in collaboration with a statistician. RESULTS: A total of 109 patients met inclusion for analysis (34 FRS, 75 SRS). The most common indication for stent insertion included sepsis (79%). On multivariate analysis both acute kidney injury as primary indication for stent insertion (odds ratio [OR] 9.16, 95% confidence interval [CI] 1.91-44.00, p=0.006) and UWT (OR 0.34, 95% CI 0.15-0.74, p=0.007) were found to be significantly associated with failed retrograde stent placement. A receiver operator characteristic curve analysis demonstrates an optimal UWT cutoff of 3.2 mm (sensitivity 60.6%, specificity 83.3%). CONCLUSIONS: Elevated UWT and acute kidney injury as an indication for urgent urinary decompression in the setting of obstructing ureteric stones are predictive of failed retrograde stent placement. These patients may benefit from upfront nephrostomy tube insertion.

Direct to cystoscopy: A prospective quality assessment of patient preferences.

INTRODUCTION: Cystourethroscopy is one of the most common procedures performed by urologists in both office and operative settings. With the recent centralization of cystoscopy at our center, we looked to assess our current delivery model, to determine whether patients prefer their initial visit to be in cystoscopy or in the clinic, followed by a cystoscopy appointment later. METHODS: We administered 500 prospective questionnaires to adults undergoing cystoscopy by 14 urologists at our center in 2017. Patient demographics were collected, along with their questionnaire results that we compared to their urologist-reported indication, results, and plan. Our primary objective was to assess whether patients prefer to be seen direct to cystoscopy (DTC) vs. a clinic appointment (CA) before cystoscopy. RESULTS: A total of 500 questionnaires were analyzed, with 336/500 (67%) patients being male. Mean age was 66 years (21-93), with 30% under 60 years. Thirty-nine percent (n=193) were undergoing their first cystoscopy, with 85% preferring DTC. There was no difference in age, gender, first-time cystoscopy, or indication for cystoscopy when comparing those who preferred DTC vs. CA. Patients who had an accurate understanding of the indication for their cystoscopy had 6.23 times higher odds of preferring DTC (p<0.05). We also identified a deficiency in patient comprehension of cystoscopy results and followup plans. CONCLUSIONS: With limited health resources, a large patient catchment area, and the majority of patients preferring to be seen DTC, there is evidence to implement a default DTC approach to booking cystoscopy clinics.

Impact of LUTS on urine volume in stone formers The impact of lower urinary tract symptomatology on urine volumes in stone formers.

INTRODUCTION: We aimed to determine if there is a correlation between International Prostate Symptom scores (IPSS) and 24-hour urine collection volumes, as patients experiencing lower urinary tract symptoms (LUTS) may have impaired ability to increase fluid intake for stone prevention. METHODS: We conducted a single-centre, retrospective review was performed of stone-formers presenting from 2014-2016. Inclusion criteria were completion of an IPSS questionnaire and a 24-hour urine collection. Exclusion criteria included symptomatic stone or urinary tract infection at time of IPSS completion, inadequate 24-hour collection, or incomplete IPSS questionnaire. RESULTS: A total of 131 patients met inclusion criteria. Stratification by IPSS severity into mild (0-7), moderate (8-19), and severe (20-35) yielded groups of n=96, 28, and 7, respectively. Linear regression modelling did not reveal a correlation between IPSS score and volume (p=0.10). When compared to those with adequate urine volumes (>2 L/day, n=65), low-volume patients (<1 L/day, n=10) had a significantly higher total IPSS (11.7 vs. 6.1; p=0.036). These groups showed significant differences in their responses to questions about incomplete emptying (p=0.031), intermittency (p=0.011), and stranguria (p=0.0020), with higher scores noted in the low urine output group. CONCLUSIONS: This study is the first to examine the correlation between IPSS and 24-hour urine volume. Though our data does not show a linear relationship between urine output and IPSS, those with lower urine volumes appear to have worse self-reported voiding symptoms when compared to those with adequate volumes (>2 L/day) for stone prevention. The overall number of patients in our study is relatively small, which may account for the lack of a relationship between IPSS and 24-hour urine volumes.

Are We Banging Our Heads Against the Wall? The Effect of Treatment Head Wear on the Outcomes of Extracorporeal Shockwave Lithotripsy.

INTRODUCTION AND OBJECTIVE: The manufacturer for the Storz Modulith SLX-F2 lithotripter recommends treatment head exchange after 1.65 million shocks. However, there is no documentation describing longevity of the treatment head with continued usage. The objective of this study is to determine whether there is a difference in stone fragmentation effectiveness with the treatment head at the beginning versus the end of its treatment life. METHODS: We conducted a retrospective chart review of 200 patients-50 consecutive patients treated immediately preceding, and following, two separate treatment head exchanges. Primary outcome measures were stone-free rate (no stone), total stone fragmentation (any decrease in size), and fragmentation rate ≤4 mm (decrease in size with largest residual fragment ≤4 mm), based on most recent follow-up imaging post shockwave. RESULTS: There were no baseline characteristic differences between the pre-exchange and postexchange groups with respect to first time lithotripsy for the stone (85% vs. 77%), stone location, preoperative stenting (3% vs. 4%), mean stone density (912 hounsfield units [HU] vs. 840 HU), mean stone size (9.0 mm vs. 8.1 mm), stone location, and mean number of shocks delivered (3105 vs. 3089). Mean time to follow-up was 2.7 weeks in both groups, with most follow-up imaging consisting of a kidney ureter bladder X-ray (87% pre-exchange vs. 85% postexchange). Stone free (34% vs. 27%), total stone fragmentation (76% vs. 76%), fragmentation ≤4 mm (48% vs. 42%), re-treatment rates (38% vs. 51%), and complication rates (6% vs. 7%), were not statistically different between the pre and postexchange groups, respectively. CONCLUSIONS: Exchanging the Storz Modulith F2 lithotripter head at the manufacturer recommended 1.65 million shocks does not affect the stone-free or fragmentation rate. If the manufacturer's recommendation for treatment head longevity is based on clinical outcomes, then there is likely room to extend this number without affecting treatment efficacy.

Changing trends in the American diet and the rising prevalence of kidney stones.

OBJECTIVE: To evaluate the trends in the American diet over the last 40 years (1974-2010), during which time the National Health and Nutrition Examination Survey data set has documented an increase in stone prevalence from 3.8% to 8.8%. MATERIALS AND METHODS: We used the National Health and Nutrition Examination Survey reported rates for stone disease (1974-2010) to compare the United States Department of Agriculture's food distribution data during the same period. Three data points for prevalence were used from the literature. We correlated these to changing lithogenic food distributions using linear models to interpolate annual changes in prevalence. Spearman correlations were performed (P ≤.05) using SAS 9.2 (SAS Institute, Cary, NC). RESULTS: Increased total daily calories (rho, 0.96; P <.001), fat (rho, 0.79; P <.001), protein (rho, 0.85; P <.001), fruit (rho, 0.6; P = .01), and vegetables (rho, 0.73; P <.001) correlated strongly with increasing stone prevalence. Dark green vegetables, flour or cereal products, fish or shellfish, corn products (including high fructose corn syrup), and added sugars also showed strong correlations with stone prevalence. Citrus fruits were negatively correlated to stone disease (rho, -0.18; P = .31). Protein, fruits and vegetables, and added sugars actually decreased in proportion to daily caloric per capita increases. CONCLUSION: Increases in caloric intake and several lithogenic foods correlate temporally with increasing stone prevalence. The nature of this relationship is difficult to determine from this data; although, clearly, American diets have changed over the last 4 decades.