Underinsurance And Multiple Surgical Treatments for Kidney Stones.

OBJECTIVE: To further elucidate the relationship between low socioeconomic status (SES) and larger, more complex stones requiring staged surgical interventions. Specifically, we aimed to determine if underinsurance (Medicaid, Medicare, and self-pay insurance types) is associated with multiple surgeries within 1 year. METHODS: We performed a retrospective longitudinal analysis of prospectively collected data from the California statewide Department of Health Care Access and Information (HCAI) dataset. We included adult patients who had their first recorded kidney stone encounter between 2009 and 2018 and underwent at least 1 urologic stone procedure. We followed these patients within the dataset for one year after their initial surgery to assess for factors predicting multiple surgical treatments for stones. RESULTS: A total of 156,319 adults were included in the study. The proportions of individuals in private insurance, Medicaid, Medicare and self-pay/indigent groups differed by the presence or absence of additional surgeries (64.0%, 13.5%, 19.4%, and 0.1%, vs 70.3%, 10.1%, 16.6%, and 0.1%, respectively). Compared to private insurance, Medicaid (1.46 [1.40-1.53] P < .001) and Medicare (1.15 [1.10-1.20] P < .001) insurance types were associated with significantly greater odds of multiple surgeries, whereas no significant association was seen in the self-pay/indigent insurance type (1.35 [0.83-2.19], P = 1.0). CONCLUSION: In a statewide, California database from 2009 to 2018, underinsured adults had higher odds of undergoing a second procedure for kidney stones within 1 year of initial surgical treatment. This study adds to the expanding body of literature linking suboptimal healthcare access and disparate outcomes for kidney stone patients.

Multi-Institutional Variation in Performance of Low-Dose Computed Tomography for the Evaluation of Suspected Nephrolithiasis.

Introduction and Objective: Guidelines from the American Urological Association (AUA) and American College of Radiology (ACR) recommend that patients with suspected nephrolithiasis undergo low-dose CT of the kidney, ureter, and bladder (LD CT KUB) as opposed to higher dose conventional imaging. We hypothesized that even at institutions with established LD protocols, higher dose imaging is common. Materials and Methods: We identified four academic medical centers where LD CT KUB protocols were implemented to yield an effective dose (EDose) consistent with national guidelines. Fifty consecutive adult patients who underwent CT KUB specifically for the evaluation of nephrolithiasis were retrospectively reviewed at each site. Patient age, sex, body mass index (BMI), imaging location, and EDose (millisieverts [mSv]) were recorded. Results: Two hundred patients with a mean age of 54 years were identified. Forty-six patients (23%) underwent CT KUB with an EDose ≤4 mSv, accounting for 10% to 48% of each institution's cohort. One hundred sixteen patients had a BMI <30, and would have been expected to receive LD CTs by the AUA criteria for LD CT KUB. Within this subset, only 37 patients (32%) actually underwent LD CT KUB. The highest dose CT KUB at each institution resulted in an EDose of 33.8 to 44.6 mSv, exceeding the recommended exposure of LD CT KUB by 10-fold. Conclusions: At academic institutions where LD CT KUB was implemented for the evaluation of nephrolithiasis, a minority of patients with BMI <30 received guideline-concordant imaging. Differences in patient BMI did not account for the variation in radiation exposure. Further research is necessary to elucidate barriers to LD CT implementation.

Community Income, Healthy Food Access, and Repeat Surgery for Kidney Stones.

OBJECTIVE: To determine if limited food access census tracts and food swamp census tracts are associated with increased risk for repeat kidney stone surgery. And to elucidate the relationship between community-level food retail environment relative to community-level income on repeat stone surgery over time. METHODS: Data were abstracted from the University of California, San Francisco Information Commons. Adult patients were included if they underwent at least one urologic stone procedure. Census tracts from available geographical data were mapped using Food Access Research Atlas data from the United States Department of Agriculture Economic Research Service. Kaplan-Meier curves were employed to illustrate time to a second surgical procedure over 5 years, and log-rank tests were used to test for statistically significant differences. A multivariate Cox regression model was used to generate hazard ratios for undergoing second surgery by group. RESULTS: A total of 1496 patients were included in this analysis. Repeat stone surgery occurred in 324 patients. Kaplan-Meier curves demonstrated a statistically significant difference in curves depicting patients living in low income census tracts (LICTs) vs those not living in LICTs (P <.001). On Cox regression models, patients in LICTs had significantly higher risk of undergoing repeat surgery (P = .011). Patients from limited food access census tracts and food swamp census tracts did not have a significantly higher adjusted risk of undergoing second surgery (P = .11 and P = .88, respectively). CONCLUSION: Income more so than food access associates with increased risk of repeat kidney stone surgery. Further research is needed to explore the interaction between low socioeconomic status and kidney stone outcomes.

Low Urologist Density Predicts High-Cost Surgical Treatment of Stone Disease.

Introduction and Objectives: Lack of access to urologic specialists is approaching crisis levels as the number of urologists is decreasing, while the demand for urologic care is increasing. The financial implications of this have not been explored. The objective of this study is to examine the impact of access and other patient factors on cost to treat urolithiasis. We hypothesized that markers of poor access would associate with higher costs of surgical encounters for patients presenting with urolithiasis. Methods: A retrospective review of prospectively collected data from the Registry for Stones of the Kidney and Ureter (ReSKU) from September 2015 to July 2018 was conducted to investigate characteristics of surgical patients treated for urinary stone disease. Univariate analysis was performed using the Welch two-sample t-test. Multivariate analysis was performed using logistic regression. Statistical analysis was performed in R version 3.5. Results: When taking into account age, delayed presentation, procedure type, stone size >20 mm, American Society of Anesthesiologists (ASA) code, gender, race, income, distance, urologist density, body mass index, diabetes, infection, education, language, insurance, and stone complexity, patients undergoing percutaneous nephrolithotomy procedure (p < 0.001; odds ratio [OR] 12.9, confidence interval [CI] 4.05-48.5), urologist density in the bottom quartile (p = 0.014; OR 4.66, CI 1.40-16.9), diabetes (p = 0.018; OR 4.38, CI 1.32-15.6), and infection (p = 0.007; OR 4.51, CI 1.55-14.0) were the only variables statistically significant for association with top quartile of total cost. Conclusions: Surgical encounter costs are largely dictated by patient clinical factors, but low regional urologist density appears to independently predicted for high-cost stone surgery. Increasing patients' access to a urologist may prove to be financially beneficial in the longitudinal reduction in health care costs for stone disease.

Influence of Socioeconomic Factors on Stone Burden at Presentation to Tertiary Referral Center: Data From the Registry for Stones of the Kidney and Ureter.

OBJECTIVE: To determine social factors associated with advanced stone disease (defined as unilateral stone burden >2 cm) at time of presentation to a regional stone referral center. Little is known about social determinants of urolithiasis. We hypothesize that socioeconomic factors impact kidney stone severity at intake to referral centers. METHODS: A retrospective review of the prospectively collected data from the Registry for Stones of the Kidney and Ureter from 2015 to 2018 was conducted to evaluate patient characteristics predictive of having a large (>2 cm) unilateral kidney stone. Data on patient age, gender, body mass index, diabetes, race, language, education level, infection, distance, income, referring regional urologist density, American Society of Anesthesiologists score, and stone analysis were evaluated. RESULTS: Complete imaging and patient variable data was present in 650 of 1142 patients including 197 patients with unilateral stone burden >2 cm. On multivariate analysis, obesity, lower education level, increased distance from the referral center, and symptoms of infection predicted for unilateral stone burden greater than 2 cm. Among 191 patients with stone analysis data present, stone type, income, and urologist density predicted for unilateral stone burden greater than 2 cm. CONCLUSION: In addition to known biological risk factors, patients with lower education levels and from regions of lower mean income were found to be more likely to present to our tertiary care center with stone burden greater than 2 cm. More research is needed to elucidate the social and societal determinants of advanced stone disease and the impact this has on population costs for stone treatment.

Assessing Cost-Effectiveness of New Technologies in Stone Management.

Diagnosis, treatment, and follow-up are all influential in determining the overall cost to the health care system for kidney stones. New innovations in the field of nephrolithiasis have been abundant, including disposable ureteroscopes, ultrasound-guided approaches to percutaneous nephrolithotomy, and advanced laser lithotripters. Identifying cost-effective treatment strategies encourages practitioners to be thoughtful about providing value-based high-quality care and remains on important principle in the treatment of urinary stone disease.

Increasing Body Mass Index Steepens the Learning Curve for Ultrasound-guided Percutaneous Nephrolithotomy.

OBJECTIVE: To define how the learning curve for success in ultrasound-guided percutaneous nephrolithotomy (PCNL) is impacted by body mass index (BMI). Previous research has shown ultrasound-guided PCNL to be an effective method of nephrolithiasis treatment comparable to fluoroscopy-guided PCNL. A common concern for the ultrasound-guided approach is potential imaging difficulty in the obese patient population. METHODS: A prospective cohort study of consecutive patients undergoing PCNL with ultrasound guidance for renal tract access was performed. Clinical data collected included success in gaining renal access with ultrasound guidance, patient BMI, and clinical outcomes over time. Nonparametric LOWESS regression modeling was performed in R using locally weighted scatterplot smoother (R version 3.3.3) for gradations of patients by BMI group (<30, 30-40, and >40). RESULTS: A total of 150 cases were examined. Case number and BMI were evaluated as continuous variables. Multivariate logistic regression revealed that BMI (P = .010; OR 0.93) and case number (P<.001; OR 1.03) were significantly correlated with ultrasound success. Sex, age, hydronephrosis, stone type, puncture location, and stone size did not influence success at obtaining ultrasound-only access in a statistically significant fashion. LOWESS regression modeling of the relationship between case number and renal access success depicts that the curve representative of the BMI >40 group is downward and right-shifted relative to the other two groups. CONCLUSION: The learning curve for successful ultrasound-guided PCNL is impacted by patient's BMI as well as case number. Increasing BMI makes access more challenging when performing ultrasound-guided PCNL.