[Contamination of urine collected for cytobacteriological examination: situation in a university hospital in Morocco]. / Contamination des urines prélevées pour examen cytobactériologique : situation dans un centre hospitalier universitaire au Maroc.

The pre-analytical step of the cytobacteriological examination of urine (CBEU) is one of the most critical in microbiology. The objectives of our study were to determine the rate of urinary contamination and to analyze the factors that would facilitate this in order to propose solutions to this problem. METHOD: This is a 26-month descriptive study including all CBEU requests to our laboratory. Urine was treated in accordance with the recommendations of the medical microbiology recommendations. Urine was considered contaminated in the case of polymorphic culture with at least three different types of germs with a count from 103 CFU/mL. RESULTS: We collected 16,412 CBEU requests. Urine was contaminated in 4,830 cases (29.43%). Of the contaminated urine, 39.23% (n=1,895) was from emergency departments, 79.44% (n=3,837) was collected in the middle of the stream, 69.83% (n=3,373) was from a female patient and 16.34% (n=789) was from children under the age of 5. DISCUSSION AND CONCLUSION: To reduce urine contamination, quality instructions describing sampling procedures should be available and samples in the middle of the stream and through the collection adhesive bags should be replaced by sus-pubic puncture samples in children, whenever the profit/risk ratio of this method is favourable.

Reducing the Risk of Indwelling Catheter-Associated Urinary Tract Infection in Female Patients by Implementing an Alternative Female External Urinary Collection Device: A Quality Improvement Project.

PURPOSE: The purpose of this quality improvement project was to reduce catheter-associated urinary tract infection (CAUTI) risk for female patients by implementing a female external urinary collection (FEUC) device with suction as an alternative to indwelling catheter (IDC). PARTICIPANTS AND SETTING: Participants were female patients admitted to our 386-bed community hospital in Southern California and who required urinary management. APPROACH: We implemented a comprehensive CAUTI prevention program in 2014 that was in place for 1.5 years before this project was started. The CAUTI prevention program was based on the US Center for Disease Control and Prevention's CAUTI prevention recommendations. To supplement our CAUTI prevention efforts in our female patients, we implemented the FEUC device in our intensive care, telemetry, medical-surgical, orthopedic, and acute rehabilitations inpatient care units. Indwelling catheter use and CAUTI cases were identified by our Infection Prevention department. OUTCOMES: Prior to introduction of the FEUC device, in 2015, the baseline female IDC utilization rate was 31.7% (7181 IDC device-days/22,656 patient-days) and the female CAUTI rate was 1.11 (8 cases/7181 IDC device-days) per 1000 days. Following introduction of the device, both rates declined. In 2016, the IDC utilization rate was 29.7% (P = .000) and the CAUTI rate was 0% (P =.005). We continued to observe a reduction in 2017 IDC utilization rates of 26% (P = .000); the 2017 CAUTI rate of 0.90 was not significantly different to our prior year rate (P = .726). IMPLICATIONS FOR PRACTICE: We found that the introduction of the FEUC device reduced the risk for CAUTI. We will continue to prioritize the use of external devices for urinary management to help reduce the risk of our patients developing CAUTI.

A Statewide Program to Improve Management of Suspected Urinary Tract Infection in Long-Term Care.

BACKGROUND/OBJECTIVES: Suspected urinary tract infection (UTI) is the most common indication for antibiotic use in long-term care (LTC). Due to the high prevalence of asymptomatic bacteriuria, for which antibiotics are not warranted, these antibiotics are frequently unnecessary. We implemented a collaborative quality improvement program to improve the management of suspected UTI in LTC residents by increasing awareness of current guidelines, with a focus on decreasing treatment in the absence of symptoms. DESIGN/INTERVENTION: Two separate collaboratives included workshops, webinars, and coaching calls. PARTICIPANTS: A total of 31 facilities participated in the first collaborative, with 17 submitting sufficient data for analysis and 34 in the second, with data analyzed from 25. MEASUREMENTS: Facilities reported monthly numbers of urine cultures, UTI diagnoses, Clostridioides difficile infections (CDIs), and resident days. RESULTS: When comparing the baseline period to the first collaborative period, the intercollaborative period to the second collaborative period, and the first collaborative period to the second, the incident rate ratios (95% confidence intervals) were 0.74 (0.68-0.81), 0.83 (0.73-0.94), and 0.63 (0.57-0.69), respectively, for urine culturing rate; 0.73 (0.64-0.83), 0.86 (0.70-1.05), and 0.60 (0.51-0.69), respectively, for UTI diagnosis rate; and 0.56 (0.40-0.82), 1.61 (0.71-4.14), and 0.45 (0.27-0.74), respectively, for CDI rate. CONCLUSION: The program we implemented was associated with reductions in urine cultures, UTI diagnosis, and CDI; and it suggests that this type of intervention can promote appropriate management of UTI in the LTC setting. J Am Geriatr Soc 68:62-69, 2019.

Evaluating Antibiotic Sensitivity Patterns of Pseudomonas in Relation to Specimen Type in Jordanian Hospital.

OBJECTIVE: To evaluate the sensitivity patterns of different antibiotics of pseudomonas in relation to specimen types. METHODS: The quantitative retrospective study was conducted at Princess Iman Research and Laboratory Sciences Centre of Royal Medical Services, Amman, Jordan. The specimens of USS, urine, cerebral spinal fluid, and blood were collected from patients, who visited the hospital from January to September 2015. Drugs analysed included ampicillin, ceftazidime, ciprofloxacin, cefotaxime, cefoxitin, nitrofurantoin and gentamicin. RESULTS: There were 358 samples collected. Ampicillin was found effective (p=0.002). There was a weaker correlation between amikacin and amoxicillin/clavulanic acid (r=-0.001). Similarly, nitrofurantoin was also effective (p=0.001), and the association between amikacin and ceftazidime was positive (r=0.998). CONCLUSIONS: The selected antibiotics were only examined, concerning the sensitivity patterns as data collected from the patients was insufficient for other drugs.

Urine collection methods used for non-toilet-trained children in pediatric emergency departments in France: A medical practice analysis.

INTRODUCTION: Since April 2015, the French Society of Pediatrics has encouraged suprapubic aspiration (SA) and urethral catheterization (UC) for urine collection in non-toilet-trained children suspected of having urinary tract infections (UTIs) and has tried to reduce the use of urine bag (UB). OBJECTIVE: To analyze the medical practices concerning urine collection methods used for non-toilet-trained children in pediatric emergency departments in France. METHODS: We conducted a descriptive medical practice study in October 2017. All members of the French Society of Pediatric Nephrology received two questionnaires about urine collection methods used for non-toilet-trained children, distinguishing between male and female patients, and about the corresponding analgesic protocols used in their pediatric emergency departments. RESULTS: In total, 26 centers completed questionnaires concerning female patients. UC was performed in cases of fever associated with urinary tract malformations in 14 of 26 centers (54%). UB was used in cases of fever of unknown origin lasting for more than 48h in 17 of 26 centers (65%), in cases of fever associated with UTI symptoms in 14 of 26 centers (54%), and in cases of fever in infants under 3 months of age in 16 of 26 centers (61%). The questionnaires concerning male patients were completed by 30 centers. UB was the initially used urine collection method in all situations with, respectively, 22 of 30 (73%), 27 of 30 (90%), 23 of 30 (77%), and 22 of 30 (73%) centers. The analgesic protocol for urine collection is not well established in France. CONCLUSION: UC for urine collection in pediatric emergency departments in France is underused despite the national recommendations and the greater diagnostic power of this method compared with UB.

The effects of sucrose on urine collection in metabolic cages.

Representative urine collection that respects the standards of animal welfare is still an issue in experimental nephrology. The commonly used metabolic cages induce stress in rodents. In mice, the volume of collected urine is sometimes insufficient for further analysis. The aim of this experiment was to analyse the effects of time of day, temperature and 2%, 5% or 10% sucrose solutions on diuresis, weight change and liquid intake of adult mice placed in metabolic cages for urine collection. Mice were placed in metabolic cages for 12 h during the day or night at standard ambient (22℃) and thermoneutral (28℃) temperatures. To determine the effect of acclimatisation, mice were placed in metabolic cages for five consecutive days. Diuresis increased with concentrations of sucrose. Body weight reduction was most rapid in the group given tap water and decreased with increasing sucrose concentrations. A drastic drop in body weight was observed in mice placed in metabolic cages for four consecutive days with access to tap water and food, indicating that time spent in metabolic cages should be kept to a minimum, as prolonged confinement in metabolic cages can be harmful to mice. The administration of concentrated sucrose solutions can potentially aid in mouse urine collection by reducing the time spent in metabolic cages. Sucrose supplementation increased the albumin/creatinine ratio. However, without showing estimates of glomerular filtration rate, renal haemodynamics, plasma electrolytes and urinary electrolyte excretions, the results of this study do not provide any conclusion about the effect of sucrose on renal function.

Measurement duration affects the calculation of whole body protein turnover kinetics but not between-day variability.

BACKGROUND: Assessment of whole body protein turnover (WBPT) can provide fundamental information about protein kinetics which underpins the conservation of lean tissue. Reliability and methodology studies on the measurement of WBPT are scarce. This study aimed to assess the effects of urine collection duration (9 versus 12 h) and the reproducibility of WBPT with the end product method calculated from ammonia as the end product. METHODS: WBPT was assessed in 21 healthy participants (11M, 10F) on 2 test days. WBPT was assessed using the end product method with a single dose of 15N glycine with ammonia as end product in a postprandial state with 9 and 12-h urine collections. RESULTS: The CV for protein flux averaged 10% and 12% for 9 and 12-h urine collections respectively. Protein flux, synthesis and balance were significantly higher and protein breakdown significantly lower with 9-h urine collections compared to 12-h collections (P < 0.01) and there was a trend towards increasingly greater overestimation of 9-h calculated WBPT kinetics with greater overall rates of WBPT. Correlations between the 9 and 12-h values were strong (r > 0.962, P < 0.001 for all variables). CONCLUSIONS: The reproducibility of WBPT with ammonia as the end product was similar to previously reported reproducibility of the gold standard precursor technique. The use of a 12-h urine collection is more effective to achieve full turnover of the ammonia free amino acid (AA) pool.

Pre-analytical Factors Influence Accuracy of Urine Spot Iodine Assessment in Epidemiological Surveys.

Urinary iodine concentration (UIC) is commonly used to assess iodine status of subjects in epidemiological surveys. As pre-analytical factors are an important source of measurement error and studies about this phase are scarce, our objective was to assess the influence of urine sampling conditions on UIC, i.e., whether the child ate breakfast or not, urine void rank of the day, and time span between last meal and urine collection. A nationwide, two-stage, stratified, cross-sectional study including 1560 children (6-12 years) was performed in 2012. UIC was determined by the Sandell-Kolthoff method. Pre-analytical factors were assessed from children's mothers by using a questionnaire. Association between iodine status and pre-analytical factors were adjusted for one another and socio-economic characteristics by multivariate linear and multinomial regression models (RPR: relative prevalence ratios). Skipping breakfast prior to morning urine sampling decreased UIC by 40 to 50 µg/L and the proportion of UIC < 100 µg/L was higher among children having those skipped breakfast (RPR = 3.2[1.0-10.4]). In unadjusted analyses, UIC was less among children sampled more than 5 h from their last meal. UIC decreased with rank of urine void (e.g., first vs. second, P < 0.001); also, the proportion of UIC < 100 µg/L was greater among 4th rank samples (vs. second RPR = 2.1[1.1-4.0]). Subjects' breakfast status and urine void rank should be accounted for when assessing iodine status. Providing recommendations to standardize pre-analytical factors is a key step toward improving accuracy and comparability of survey results for assessing iodine status from spot urine samples. These recommendations have to be evaluated by future research.

A Novel Urine-Based Assay for Bladder Cancer Diagnosis: Multi-Institutional Validation Study.

BACKGROUND: CellDetect is a unique histochemical stain enabling color and morphological discrimination between malignant and benign cells based on differences in metabolic signature. OBJECTIVE: The objective of the present study was to validate the performance of this assay in a controlled, blinded, multicenter study. DESIGN, SETTING, AND PARTICIPANTS: The study, conducted in nine hospitals, included patients with documented history of bladder cancer, monitored for urothelial carcinoma (UCC) or scheduled for bladder cancer surgery. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cystoscopy and/or biopsy were used as a reference standard to determine sensitivity and specificity. Smears were stained by CellDetect and interpreted by two cytologists blinded to the patient's final diagnosis. The findings were compared with those of standard urine cytology and BTA stat. RESULTS AND LIMITATIONS: Two hundred and seventeen voided urine specimens were included. Ninety-six (44%) were positive by histology and 121 (56%) were negative by either cystoscopy or histology. The overall sensitivity of CellDetect was 84%. Notably, the sensitivity for detecting low-grade nonmuscle-invasive bladder cancer tumors was greater than this of BTA stat (78% vs 54%) and more than two-fold higher compared with standard cytology (33%, p ≤ 0.05). The specificity was 84% in patients undergoing routine surveillance by cystoscopy. At a median follow-up of 9 mo, 21% of the patients with positive CellDetect and negative reference standard developed UCC, which was significantly higher compared with the 5% of the true negative cases. Limitations include the lack of instrumental urine samples and the lack of patients with nongenitourinary cancers in the study population. CONCLUSIONS: This study validates the performance of CellDetect as a urine-based assay to identify UCC in patients with history of bladder cancer. The high sensitivity was maintained across all cancer grades and stages without compromising the assay specificity. Further studies are required to test whether this novel stain can be incorporated in routine bladder cancer surveillance as a noninvasive alternative to cystoscopy. PATIENT SUMMARY: Surveillance of bladder cancer requires frequent invasive procedures. In the present study, we validate the ability of a novel biomarker to accurately identify early-stage tumors in urine specimens for the noninvasive monitoring of patients with history of bladder cancer.

Factors Associated with Compliance in Submitting 24-Hour Urine Collections in an Underserved Community.

PURPOSE: Patients living in underserved areas do regularly express an interest in stone prevention; however, factors limiting participation, aside from obvious cost considerations, are largely unknown. To better understand factors associated with compliance with submitting 24-hour urine collections, we reviewed our patient experience at the kidney stone clinic at a hospital that provides care for an underserved urban community. MATERIALS AND METHODS: A retrospective chart review of patients treated for kidney and/or ureteral stones between August 2014 and May 2016 was performed. Patient demographics, medical characteristics, stone factors, and compliance data were compiled into our data set. Patients were divided into two groups: those who did and did not submit the requested initial 24-hour urine collection. Analysis of factors related to compliance was performed using univariate analysis and multivariate logistic regression. RESULTS: A total of 193 patients met inclusion criteria for our study, 42.5% (82/193) of whom submitted 24-hour urine samples. Of the 82 collections submitted, 34.1% (28/82) were considered inadequate by creatinine level. A second urine collection within 6 months was obtained in 14.0% (27/193) of patients. Univariate analysis demonstrated that African American (AA) patients were less likely to submit an initial 24-hour urine collection than Caucasian patients (collected: 30.9% vs 51.8%; p < 0.05, respectively). Patients with a family history of kidney stones were more likely to submit an initial 24-hour urine collection than patients without a family history of kidney stones (61.1% vs 38.2%, p < 0.02, respectively). On multivariate analysis, both factors remained significant predictors of compliance with submitting a 24-hour urine collection. CONCLUSIONS: In our underserved patient population, AA patients were half as likely to submit a 24-hour urine collection than Caucasian patients, whereas patients with a positive family history of stones were more than twice as likely to submit than patients with no family history.

Storage Time and Urine Biomarker Levels in the ASSESS-AKI Study.

BACKGROUND: Although stored urine samples are often used in biomarker studies focused on acute and chronic kidney disease, how storage time impacts biomarker levels is not well understood. METHODS: 866 subjects enrolled in the NIDDK-sponsored ASsessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) Study were included. Samples were processed under standard conditions and stored at -70°C until analyzed. Kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), and liver fatty acid binding protein (L-FABP) were measured in urine samples collected during the index hospitalization or an outpatient visit 3 months later. Mixed effects models were used to determine the effect of storage time on biomarker levels and stratified by visit. RESULTS: Median storage was 17.8 months (25-75% IQR 10.6-23.7) for samples from the index hospitalization and 14.6 months (IQR 7.3-20.4) for outpatient samples. In the mixed effects models, the only significant association between storage time and biomarker concentration was for KIM-1 in outpatient samples, where each month of storage was associated with a 1.7% decrease (95% CI -3% to -0.3%). There was no relationship between storage time and KIM-1 levels in samples from the index hospitalization. CONCLUSION: There was no significant impact of storage time over a median of 18 months on urine KIM-1, NGAL, IL-18 or L-FABP in hospitalized samples; a statistically significant effect towards a decrease over time was noted for KIM-1 in outpatient samples. Additional studies are needed to determine whether longer periods of storage at -70°C systematically impact levels of these analytes.

Validación de un método rápido en orina por lC/MS/MS para la búsqueda de compuestos empleados en sumisión química y su aplicación a muestras reales / Validation of a fast screening method in urine by lC/MS/MS for compounds used in drug-facilitated crime (DFC) and its application to real samples

La Oficina de Naciones Unidas contra la Droga y el Delito (UNODC) en 2011 señala que "El delito facilitado por drogas (DFD) es una expresión general que abarca la violación y otras agresiones sexuales, el robo con violencia o intimidación, la extorsión de dinero y los malos tratos deliberados de ancianos o niños bajo la influencia de sustancias sicotrópicas". En este trabajo se validó un método cualitativo y rápido a partir de muestras de orina por LC/MS/MS para 39 compuestos comprendidos en los listados de sumisión química. El objetivo fue alcanzar un límite de detección un 50 % por debajo de la concentración propuesta como "Límites mínimos de funcionamiento exigidos (MRPL)" por la UNODC, para poder ser aplicado a muestras reales.

The United Nations Office on Drugs and Crime (UNODC) in 2011, states that "The Drug-facilitated crime (DFC) is a general term that includes rape or other sexual assault, robbery, money extortion, as well as the deliberate maltreatment of the elderly or children under the influence of psychotropic substances". In this work we validated a qualitative and fast method from urine samples by LC/MS/MS for 39 compounds included in the Drug-facilitated crime lists. The aim was to reach a detection limit of 50% below the proposed concentration as "minimum required performance limits (MRPL)" by UNODC in order to be applied in real samples.

How Much Information is Lost When You Only Collect One 24-Hour Urine Sample during the Initial Metabolic Evaluation?

PURPOSE: During the initial metabolic evaluation the need for 1 vs 2, 24-hour urine collections is debated. While data suggest that mean urine chemistry measures are similar on consecutive samples, it remains unclear how much, if any, information is lost when only 1 sample is collected. MATERIALS AND METHODS: Using analytical files from Litholink Corporation® (1995 to 2013) we identified adults with kidney stones who underwent initial metabolic testing. Next we determined the subset of patients who collected 2, 24-hour urine samples with urine creatinine varying by 10% or less during a 7-day time window. We then examined the degree of variability in urine chemistry profiles. Specifically we calculated the mean absolute value of the difference between samples as well as the percent difference for individual urine parameters. RESULTS: We identified 70,192 patients meeting our eligibility criteria. While the overall means for individual urine parameters did not vary between samples, the percent difference between the samples varied widely. For example, nearly 1 in 3 patients had a 30% or greater difference in urine calcium and volume between 2 consecutive samples. We noted that inconsistencies between samples often involved multiple parameters. For instance, 29% and 25% of patients had a 20% difference in 2 and 3 or more parameters, respectively. CONCLUSIONS: We observed substantial differences between consecutive 24-hour urine samples that could affect clinical decision making. In light of these findings clinicians must weigh the information lost from only 1 collection vs the burden to the patient of collecting 2.

Equivalence of afternoon spot and 24-h urinary hydration biomarkers in free-living healthy adults.

BACKGROUND/OBJECTIVES: Urinary biomarkers of hydration (urine osmolality, UOsm; urine specific gravity, USG) follow circadian variations. For individuals, researchers and health-care professionals, there is value in identifying time frames during which spot values of UOsm and USG are representative of 24-h values in healthy young adults. SUBJECTS/METHODS: Eighty-two free-living adults (22.3±2.9 years, 22.2±1.5 kg/m(2)) collected individual urine voids over a 24-h period. UOsm and USG were measured on each void and on the pooled 24-h sample. To determine the time of day when a spot sample was likely to be equivalent to the 24-h value, daytime voids were binned by time and equivalence was tested for each 2-h window. Equivalence was a priori defined as being within 100 mOsm/kg (UOsm) and within 0.003 units (USG) of 24-h values. RESULTS: For both UOsm and USG, voids between 1400 and 2000 hours produced values that were equivalent to the 24-h sample, whereas earlier voids tended to overestimate 24-h UOsm and USG. For windows 1401-1600 hours, 1601-1800 hours and 1801-2000 hours, the mean difference (95% confidence interval) between spot and 24-h UOsm (mOsm/kg) was -25 (-72; 22), 28 (-35; 92) and 12 (-41; 66), respectively, whereas for USG the difference was 0.0014 (-0.0028; -0.0001), 0.0001 (-0.0017; 0.0019) and 0.0005 (-0.0018; 0.0009), respectively. CONCLUSIONS: In free-living healthy French adults, 24-h urine concentration can be approximated from a mid- to late-afternoon spot urine sample. This finding suggests that an afternoon sample may be an accurate and practical tool for hydration monitoring, useful to individuals and health-care practitioners.

How and when nurses collect urine cultures on catheterized patients: A survey of 5 hospitals.

BACKGROUND: Obtaining a specimen for urine culture is a key element in evaluating for catheter-associated urinary tract infections (CAUTIs). Evaluating nurses' knowledge regarding appropriate reasons and methods to obtain urine culture specimens are the first steps to improving practice. METHODS: Nurses at 5 hospitals completed a 40-question survey regarding their knowledge, training, and practices of appropriate reasons for obtaining urine cultures. The survey included different scenarios of patients with urinary catheters and when they would expect to obtain urine cultures. A 12-point scoring system calculated responses regarding urine collection appropriateness. RESULTS: There were 394 nurses who responded to the survey. Of them, 76.1% reported receiving education on CAUTI risk reduction within the last 12 months. Although 327 (83%) of all nurses surveyed reported that they never collect urine samples by draining directly from the drainage bag, only 58.4% viewed others to be fully compliant with that standard (P < .001). Nurses who considered their knowledge to be above average to excellent had similar knowledge assessment scores (out of 12 points) for triggers to obtain urine cultures (mean score, 4.9 ± 1.72) compared with those that reported average to poor knowledge (mean score, 4.64 ± 1.78; P = .15). CONCLUSIONS: Important opportunities exist for nurses to optimize the decisions to obtain urine cultures and the process for obtaining them. Addressing nurses' knowledge and practice may lead to more appropriate use of urine cultures.

Comparison between Urine Protein: Creatinine Ratios of Samples Obtained from Dogs in Home and Hospital Settings.

BACKGROUND: The urine protein:creatinine ratio (UPC) is used to quantify urine protein excretion and guide recommendations for monitoring and treatment of proteinuria. HYPOTHESIS/OBJECTIVES: Home urine samples will have lower UPCs than hospital samples. The objectives were to compare UPCs of samples collected in each setting and to determine whether environment of sample collection might affect staging, monitoring or treatment recommendations. ANIMALS: Twenty-four client-owned dogs. METHODS: Prospective, nonmasked study. Clients collected a urine sample from their dog at home and a second sample was collected at the hospital. Dogs receiving corticosteroids or angiotensin-converting enzyme inhibitors were excluded, as were those with urine samples of inadequate volume, no protein on dipstick analysis, or active urine sediment. Samples were refrigerated after collection, dipstick and sediment evaluations were completed and each sample was frozen at -80°C within 12 hours. UPCs were performed on frozen samples within 2 months. RESULTS: From 81 paired samples, 57 were excluded. Of the remaining 24, 12/24 (50%) had higher hospital sample UPCs, 9/24 (38%) had identical UPCs, and 3/24 (12%) had lower hospital UPCs. The UPCs of hospital samples were higher than home samples for the total population (P = .005) and the subset with UPC > 0.5 (P = .001). CONCLUSIONS: Setting and related circumstances of urine collection in dogs is associated with UPC differences; results are usually higher in hospital than in home samples. This difference has the potential to affect clinical interpretation.

Number and frequency of albuminuria measurements in clinical trials in diabetic nephropathy.

BACKGROUND AND OBJECTIVES: Albuminuria change is often used to assess drug efficacy in intervention trials in nephrology. The change is often calculated using a variable number of urine samples collected at baseline and end of treatment. Yet more albuminuria measurements usually occur. Because albuminuria shows a large day-to-day variability, this study assessed to what extent the average and the precision of the antialbuminuric drug effect varies with the number of urine collections at each visit and the number of follow-up visits. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study used data from three randomized intervention trials (Aliskiren Combined with Losartan in Type 2 Diabetes and Nephropathy, Selective Vitamin D Receptor Activation for Albuminuria Lowering, and Residual Albuminuria Lowering with Endothelin Antagonist Atrasentan) including patients with type 2 diabetes and macroalbuminuria. Albuminuria-lowering drug effects were estimated from one, two, or three urine collections at consecutive days before each study visit and reported as albuminuria change from baseline to end of treatment or the change over time considering an average of all follow-up albuminuria measurements. RESULTS: Increasing the number of urine collections for an albuminuria measurement at baseline and end of treatment or using all study visits during follow-up did not alter the average drug effect. The precision of the drug effect increased (decreased SEM) when the number of study visits and the number of urine collections per visit were increased. Using all albuminuria measurements at all study visits led to a 4- to 6-fold reduction in sample size to detect a 30% albuminuria-lowering treatment effect with 80% power compared with using baseline and end-of-treatment albuminuria measurements alone. CONCLUSIONS: Increasing the number of urine collections per study visit and the number of visits over time does not change the average drug effect estimate but markedly increases the precision, thereby enhancing statistical power. Thus, clinical trial designs in diabetic nephropathy using albuminuria as an end point can be significantly improved, leading to smaller sample sizes and less complex trials.

Predicting Patients with Inadequate 24- or 48-Hour Urine Collections at Time of Metabolic Stone Evaluation.

PURPOSE: We aimed to understand the characteristics of patients who are less likely to submit adequate urine collections at metabolic stone evaluation. METHODS: Inadequate urine collection was defined using two definitions: (1) Reference ranges for 24-hour creatinine/kilogram (Cr/24) and (2) discrepancy in total 24-hour urine Cr between 24-hour urine collections. There were 1502 patients with ≥1 kidney stone between 1998 and 2014 who performed a 24- or 48-hour urine collection at Northwestern Memorial Hospital and who were identified retrospectively. Multivariate analysis was performed to analyze predictor variables for adequate urine collection. RESULTS: A total of 2852 urine collections were analyzed. Mean age for males was 54.4 years (range 17-86), and for females was 50.2 years (range 8-90). One patient in the study was younger than 17 years old. (1) Analysis based on the Cr 24/kg definition: There were 50.7% of patients who supplied an inadequate sample. Females were nearly 50% less likely to supply an adequate sample compared with men, P<0.001. Diabetes (odds ratio [OR] 1.42 [1.04-1.94], P=0.026) and vitamin D supplementation (OR 0.64 [0.43-0.95], P=0.028) predicted receiving an adequate/inadequate sample, respectively. (2) Analysis based on differences between total urinary Cr: The model was stratified based on percentage differences between samples up to 50%. At 10%, 20%, 30%, 40%, and 50% differences, inadequate collections were achieved in 82.8%, 66.9%, 51.7%, 38.5%, and 26.4% of patients, respectively. Statistical significance was observed based on differences of ≥40%, and this was defined as the threshold for an inadequate sample. Female sex (OR 0.73 [0.54-0.98], P=0.037) predicted supplying inadequate samples. Adequate collections were more likely to be received on a Sunday (OR 1.6 [1.03-2.58], P=0.038) and by sedentary workers (OR 2.3 [1.12-4.72], P=0.023). CONCLUSION: Urine collections from patients during metabolic evaluation for nephrolithiasis may be considered inadequate based on two commonly used clinical definitions. This may have therapeutic or economic ramifications and the propensity for females to supply inadequate samples should be investigated further.