Changing incidence of factitious renal stone disease
.

PURPOSE: We sought to describe patterns of factitious urinary stone submission over time by investigating a contemporary stone analysis database and comparing two distinct time points. MATERIALS AND METHODS: We retrospectively reviewed a single stone analysis lab database at two time points, 1990 and 2010, and compared total incidence of factitious stone submission, as well as gender patterns and type of factitious stone submitted. RESULTS: A total of 27,014 stones were analyzed, 16,216 (60%) from 1990 and 10,798 (40%) from 2010 with a decrease in total incidence from 2.6% (428/16,216) in 1990 to 1.2% (131/10,798) in 2010 (p < 0.001). In 1990, women were significantly more likely to submit a factitious stone (RR 1.5, 95% CI 1.4 - 1.7, p < 0.001), while in 2010 there was no gender difference (RR 0.9, 95% CI 0.8 - 1.03, p < 0.05). Plant material and geologic material represented the most common factitious stone types respectively, in both 1990 and 2010. CONCLUSION: In the largest contemporary review of spurious urinary stones, we find a decreased incidence and increased gender equivalence of factitious urinary stones in 2010 compared to 1990.
.

Cost-effectiveness comparison of ureteral calculi treated with ureteroscopic laser lithotripsy versus shockwave lithotripsy.

PURPOSE: To evaluate the cost-effectiveness of shockwave lithotripsy (SWL) versus ureteroscopic lithotripsy (URS) for patients with ureteral stones less than 1.5 cm in diameter. METHODS: Patient age, stone diameter, stone location, and stone-free status were recorded for patients treated with SWL or URS for ureteral stones under 1.5 cm over a 1 year period. Institutional charges were obtained from in-house billing. A decision analysis model was constructed to compare the cost-effectiveness of SWL and URS using our results and success rates for modeling. Three separate models were created to reflect differing practice patterns. RESULTS: A total of 113 patients were included-51 underwent SWL and 62 underwent URS as primary treatment. Single procedure stone-free rates for SWL and URS were 47.1 and 88.7 %, respectively (p < 0.002). Decision analysis modeling demonstrated cost-effectiveness of SWL when SWL single procedure stone-free rates (SFR) were greater than or equal to 60-64 % or when URS single procedure SFRs were less than or equal to 57-76 %, depending on practice patterns. CONCLUSIONS: This retrospective study revealed superior SFR for ureteral stones less than 1.5 cm treated with URS compared to SWL. Our decision analysis model demonstrated that when SFR for SWL is less than 60-64 % or is greater than 57-76 % for URS, SWL is not a cost-effective treatment option. Based on these findings, careful stratification and selection of stone patients may enable surgeons to increase the cost-effectiveness of SWL.

Cost-effectiveness of anti-retropulsion devices for ureteroscopic lithotripsy.

PURPOSE: We evaluated the cost-effectiveness of anti-retropulsion devices used during ureteroscopic lithotripsy. MATERIALS AND METHODS: A decision analysis model was constructed to compare the cost-effectiveness of ureteroscopic lithotripsy with vs without an anti-retropulsion device. The risk of stone retropulsion was determined from published data in the English language literature. Expected value calculations were used to determine whether the additional cost of a device would be cost-effective to prevent secondary procedures used to treat retropulsed stones. Device cost was determined using the average cost of all commercially available devices. RESULTS: It became cost-effective to use an anti-retropulsion device at or above a 6.3% retropulsion rate. The weighted probability of retropulsion with vs without an anti-retropulsion device was 98.1% vs 83.7%. The estimated costs of secondary procedures needed to treat retropulsed stones were $5,290 for shock wave lithotripsy and $6,390 for ureteroscopy. Average device cost was $278. Thus, the average additional cost of ureteroscopic lithotripsy with vs without an anti-migration device would be $384 vs $952. CONCLUSIONS: It is cost-effective to use an anti-retropulsion device at a retropulsion rate of greater than 6.3%.

Recording urinary flow and lower urinary tract symptoms using sonouroflowmetry.

INTRODUCTION: To assess the accuracy of sonouroflow (SUF), an at-home, wireless-based acoustic system for recording lower urinary tract symptoms (LUTS) and urinary flow rate, and to compare test-to-test variability in flow parameters recorded using this new portable method with those obtained by conventional uroflowmetry. MATERIALS AND METHODS: An initial pilot study evaluated the technical feasibility of the SUF system. Subsequently, test-to-test variability was compared between sonourograms (SUFm) and standard uroflowmetry recordings. Uroflowmetry tests were performed at the urology office at pre-set times. SUF tests were performed at home on a schedule in keeping with the subjects' normal habits. RESULTS: In the initial feasibility study, 94% of SUFm recordings obtained from male volunteers displayed regular bell-shaped flow curves comparable to those recorded by standard uroflowmetry; significant variability was noted among female volunteers. In the comparative study, the coefficient of variation for SUFm-derived values was significantly lower for voiding time (p < 0.001) and significantly higher for average flow rate (p = 0.009) than that obtained from standard uroflowmetry recordings; maximum flow rate and time to maximum flow were not significantly different between methods. Box-and-whisker plots showed reduced test-to-test variability in the SUFm dataset for voiding time, maximum flow rate and time to maximum flow rate in 62.5%, 43.75% and 56%, respectively, of study subjects. CONCLUSIONS: The SUF system is easy to use and yields results comparable to those of standard uroflowmetry. Integration of recordings of LUTS with flow parameters and lower test-to-test variability suggest the potential of SUF for clinical applications.

Economic Evaluation of 1470 nm Diode Laser Enucleation vs Bipolar Transurethral Resection of the Prostate.

Purpose: Large meta-analyses demonstrate the noninferiority of laser enucleation to transurethral resection of the prostate (TURP) with regard to long-term efficacy and reoperation rate. Although the 1470 nm diode laser enucleation of the prostate (DiLEP) is superior in hemostasis and surgical visibility, its complexity and associated longer operative time limit its widespread usage. The objective of this study was to generate long-term cost estimates for bipolar TURP and DiLEP, taking into account perioperative and adverse event costs. Materials and Methods: This is a retrospective review of patients who underwent DiLEP (n = 114; November 2016 to February 2020) or TURP (n = 194; January 2016 to December 2018). A decision analysis model was constructed to compare costs of the primary procedure and subsequent complications taking into account disposable costs, operating room time, length of stay, reoperation rates, and readmissions. Costs were estimated from internal data, published literature and Medicare procedure costs. Markov modeling was used to create cost projections up to 10 years. Results: DiLEP was associated with shorter length of stay and fewer total complications, but longer operative times and greater initial costs. Cost were recuperated at 8 years postoperatively. At 10 years postoperatively, DiLEP represented approximately $664 cost savings per patient over TURP. Conclusions: DiLEP is a cost-effective alternative to TURP for the treatment of benign prostatic hyperplasia in the properly selected patient. DiLEP has greater initial costs due to longer operative times. Costs are recuperated by 10 years postoperatively due to higher rate of same-day discharges, and lower complication and reoperation rates, incurring a $664 cost savings per patient treated by DiLEP relative to TURP.

A Decision Analysis of Observation vs Immediate Reintervention for Asymptomatic Residual Fragments Less than 4 mm Following Ureteroscopic Lithotripsy.

INTRODUCTION: We performed a decision analysis model of the cost-effectiveness of observation vs intervention for asymptomatic residual fragments less than 4 mm in diameter following ureteroscopic holmium laser lithotripsy. METHODS: Outcomes data from a retrospective analysis evaluating the natural history, complications and reintervention rates of asymptomatic residual stone fragments performed by the EDGE (Endourology Disease Group for Excellence) Research Consortium were used. A decision analysis model was constructed to compare the cost-effectiveness of initial observation of residual fragments to immediate intervention. Cost of observation included emergency room visits, hospitalizations and reinterventions. The cost analysis model extended to 3 years to account for delayed reintervention rates for fragments less than 4 mm. Costs of emergency department visits, readmissions and reinterventions were calculated based on published figures from the literature. RESULTS: Decision analysis modeling demonstrated that when comparing initial observation to immediate reintervention, the cost was $2,183 vs $4,424. The difference in cost was largely driven by the fact that over 3 years, approximately 55% of all patients remained asymptomatic and did not incur additional costs. This represents an approximate annual per patient savings of $747, and $2,241 over 3 years when observation is selected over immediate reintervention. CONCLUSIONS: Our decision analysis model demonstrates superior cost-effectiveness for observation over immediate reintervention for asymptomatic residual stones less than 4 mm following ureteroscopic lithotripsy. Based on these findings careful stratification and selection of patients may enable surgeons to improve cost-effectiveness of managing small, asymptomatic residual fragments following ureteroscopic lithotripsy.

Crumpled surface structures.

We present a scalable patterning method based on surface plate buckling, or crumpling, to generate a variety of topographies that can dynamically change shape and aspect ratio in response to stimuli.

Changes in stone composition over two decades: evaluation of over 10,000 stone analyses.

To examine the changes in stone composition from 1990 to 2010. A retrospective review was performed of all renal and ureteral stones submitted from the state of Massachusetts to a single laboratory (Laboratory for Stone Research, Newton, MA) for the years 1990 and 2010. Stone composition was determined by infrared spectroscopy and/or polarizing microscopy. A total of 11,099 stones were evaluated (56.7% from 1990, 43.3% from 2010). From 1990 to 2010, the percentage of stones from females (i.e., female/male ratio) increased significantly (29.8% in 1990 to 39.1% in 2010, p < 0.001). Among women, from 1990 to 2010, there was a significant increase in stones which were >50% uric acid (7.6-10.2%, p < 0.005) and a significant decrease in struvite stones (7.8-3.0%, p < 0.001). Among women with calcium stones, the % apatite per stone decreased significantly (20.0 vs. 11.7%, p < 0.001). Among men, there were no changes in stones which were majority uric acid (11.7-10.8%, p = 0.2). Among men with calcium stones, the % apatite per stone increased significantly (9.8 vs. 12.5%, p < 0.001). Males also demonstrated a significant increase in both cystine (0.1-0.6%, p < 0.001) and struvite stones (2.8-3.7%, p = 0.02). The epidemiology of stone disease continues to evolve and appears to vary according to gender. While some of these findings may be related to population changes in body mass index and obesity, the etiology of others remains unclear.

Cost-effectiveness comparison of renal calculi treated with ureteroscopic laser lithotripsy versus shockwave lithotripsy.

PURPOSE: To evaluate the cost-effectiveness of shockwave lithotripsy (SWL) vs ureteroscopic lithotripsy (URS) for patients with renal stones <1.5 cm in diameter. METHODS: Patient age, stone diameter, stone location, and stone-free status were recorded for patients treated with SWL or URS for renal stones <1.5 cm in maximal diameter over a 1-year period. Institutional charges were obtained from in-house billing. A decision analysis model was constructed to compare the cost-effectiveness of SWL and URS and using our results and success rates for modeling. Three separate models were created to reflect practice patterns for SWL. RESULTS: One hundred fifty-eight patients were included in the study-78 underwent SWL and 80 underwent URS as primary treatment. Single procedure stone-free rates (SFR) for SWL and URS were 55% and 95%, respectively (P<0.0001). Decision analysis modeling demonstrated cost-effectiveness of SWL when SWL single procedure SFR were 65% to 67% or when URS single procedure SFR was 72% to 84%. CONCLUSIONS: This retrospective study revealed superior SFR results for renal stones <1.5 cm for URS compared with SWL. Our decision analysis model demonstrates that for SWL SFR less than 65% to 67% or for URS SFR greater than 72% to 84%, SWL is not a cost-effective treatment option. Based on these findings, careful stratification and selection of stone patients may enable surgeons to increase the cost-effectiveness of SWL.

A non-anesthetized mouse model for recording sensory urinary bladder activity.

The goal of this study was to develop an in vivo awake mouse model for extracellular bladder sensory nerve recording. A bipolar 125-µm silver electrode was positioned under a single postganglionic bladder nerve. Efferent nerve signals were eliminated by tying off the postganglionic bladder nerve between the major pelvic ganglion and the recording electrode. Sensory nerve activity was measured in the conscious animals 48 h after surgery during continuous intravesical infusion of 0.9% saline/0.5% acetic acid followed by 0.5% acetic acid with capsazepine (10 µM) at a rate of 0.75 ml/h. Continuous infusion of 0.9% NaCl led to a gradual increase in the frequency of sensory nerve firing that peaked upon reaching threshold pressure. Non-micturition contractions were observed in some animals during filling and other animals exhibited only minimal pressure fluctuations; both types of events were associated with a rise in sensory nerve activity. Intravesical infusion of 0.5% acetic acid reduced the intermicturition interval. This was associated with a 2.1-fold increase in bladder pressure during filling and a two-fold increase at both threshold and micturition pressures. Concurrent with these changes, sensory activity increased 2.8-fold during filling and 2.4-fold at threshold pressure. Subsequent intravesical infusion of capsazepine in 0.5% acetic acid reduced filling and threshold pressures by 21 and 31.2%, respectively, and produced corresponding decreases of 36 and 23.4% in sensory nerve activity. The current study shows that multifiber sensory nerve recordings can be reproducibly obtained from conscious mice.