Assessment of urine sample collection and processing variables for extracellular vesicle-based proteomics.

Extracellular vesicles (EVs) in urine are a promising source for developing non-invasive biomarkers. However, urine concentration and content are highly variable and dynamic, and actual urine collection and handling often is nonideal. Furthermore, patients such as those with prostate diseases have challenges in sample collection due to difficulties in holding urine at designated time points. Here, we simulated the actual situation of clinical sample collection to examine the stability of EVs in urine under different circumstances, including urine collection time and temporary storage temperature, as well as daily urine sampling under different diet conditions. EVs were isolated using functionalized EVtrap magnetic beads and characterized by nanoparticle tracking analysis (NTA), western blotting, electron microscopy, and mass spectrometry (MS). EVs in urine remained relatively stable during temporary storage for 6 hours at room temperature and for 12 hours at 4 °C, while significant fluctuations were observed in EV amounts from urine samples collected at different time points from the same individuals, especially under certain diets. Sample normalization with creatinine reduced the coefficient of variation (CV) values among EV samples from 17% to approximately 6% and facilitated downstream MS analyses. Finally, based on the results, we applied them to evaluate potential biomarker panels in prostate cancer by data-independent acquisition (DIA) MS, presenting the recommendation that can facilitate biomarker discovery with nonideal handling conditions.

Are individual analyses of multiple short urine collections throughout the 24 hours superior to a standard 24-hour urine collection in precipitation risk assessment of healthy subjects?

PURPOSE: The commonly used 24-hour collection technique has been the mainstay of diagnosis for supersaturation but has some certain limitations. Hence, superiority of multiple short urine collections as a new alternative in precipitation risk assessment was assessed compared to the standard 24-hour urine collection among healthy subjects. MATERIALS AND METHODS: Individual urine samples of 26 healthy subjects were acquired every 2 to 3 hours throughout the 24 hours. Urine samples were obtained and the time and volume of each sample were recorded. Urinary constituents involved in precipitation including, sodium-potassium, chloride, calcium, phosphate, citrate, magnesium, urea, creatinine and pH were measured. A simulated 24-hour collection was recalculated by the totalling of all shorter urine collections volume and urinary constituents excretions throughout the day. RESULTS: Urine pH, urine creatinine and precipitation rate had a significantly lower values in 24-hours urine collection compared to one individual value of multiple urine collections by -0.769 (P < .0001), -7.305 (P < .0001), and - 12.838 (P < .0001), respectively. However, calcium (2.697, P < .0001), citrate (3.54, P < .0001), total phosphate (19.961, P < .0001) and total creatinine (9.579, P < .0001) had statistically significantly higher values in the 24-hours urine collection compared to individual value of multiple urine collections. CONCLUSION: Based on the results, individual analysis of multiple shorter urine collections throughout the day improves the ability of identifying supersaturation points, precipitation risk zones and may potentially improve risk assessment compared to the 24-hour urine collection method.

Liquid gold: the cost-effectiveness of urine sample collection methods for young precontinent children.

BACKGROUND: Urinary tract infection (UTI) is a common childhood infection. Many febrile children require a urine sample to diagnose or exclude UTI. Collecting urine from young children can be time-consuming, unsuccessful or contaminated. Cost-effectiveness of each collection method in the emergency department is unknown. OBJECTIVE: To determine the cost-effectiveness of urine collection methods for precontinent children. METHODS: A cost-effectiveness analysis was conducted comparing non-invasive (urine bag, clean catch and 5 min voiding stimulation for clean catch) and invasive (catheterisation and suprapubic aspirate (SPA)) collection methods, for children aged 0-24 months in the emergency department. Costs included equipment, staff time and hospital bed occupancy. If initial collection attempts were unsuccessful subsequent collection using catheterisation was assumed. The final outcome was a definitive sample incorporating progressive dipstick, culture and contamination results. Average costs and outcomes were calculated for initial collection attempts and obtaining a definitive sample. One-way and probabilistic sensitivity analyses were performed. RESULTS: For initial collection attempts, catheterisation had the lowest cost per successful collection (GBP£25.98) compared with SPA (£37.80), voiding stimulation (£41.32), clean catch (£52.84) and urine bag (£92.60). For definitive collection, catheterisation had the lowest cost per definitive sample (£49.39) compared with SPA (£51.84), voiding stimulation (£52.25), clean catch (£64.82) and urine bag (£112.28). Time occupying a hospital bed was the most significant determinant of cost. CONCLUSION: Catheterisation is the most cost-effective urine collection method, and voiding stimulation is the most cost-effective non-invasive method. Urine bags are the most expensive method. Although clinical factors influence choice of method, considering cost-effectiveness for this common procedure has potential for significant aggregate savings.

The International Consortium for Quality Research on Dietary Sodium/Salt (TRUE) position statement on the use of 24-hour, spot, and short duration (<24 hours) timed urine collections to assess dietary sodium intake.

The International Consortium for Quality Research on Dietary Sodium/Salt (TRUE) is a coalition of intentional and national health and scientific organizations formed because of concerns low-quality research methods were creating controversy regarding dietary salt reduction. One of the main sources of controversy is believed related to errors in estimating sodium intake with urine studies. The recommendations and positions in this manuscript were generated following a series of systematic reviews and analyses by experts in hypertension, nutrition, statistics, and dietary sodium. To assess the population's current 24-hour dietary sodium ingestion, single complete 24-hour urine samples, collected over a series of days from a representative population sample, were recommended. To accurately estimate usual dietary sodium at the individual level, at least 3 non-consecutive complete 24-hour urine collections obtained over a series of days that reflect the usual short-term variations in dietary pattern were recommended. Multiple 24-hour urine collections over several years were recommended to estimate an individual's usual long-term sodium intake. The role of single spot or short duration timed urine collections in assessing population average sodium intake requires more research. Single or multiple spot or short duration timed urine collections are not recommended for assessing an individual's sodium intake especially in relationship to health outcomes. The recommendations should be applied by scientific review committees, granting agencies, editors and journal reviewers, investigators, policymakers, and those developing and creating dietary sodium recommendations. Low-quality research on dietary sodium/salt should not be funded, conducted, or published.

The Science of Salt: Updating the evidence on global estimates of salt intake.

The Global Burden of Disease (GBD) 2010 study estimated national salt intake for 187 countries based on data available up to 2010. The purpose of this review was to identify studies that have measured salt intake in a nationally representative population using the 24-hour urine collection method since 2010, with a view to updating evidence on population salt intake globally. Studies published from January 2011 to September 2018 were searched for from MEDLINE, Scopus, and Embase databases using relevant terms. Studies that provided nationally representative estimates of salt intake among the healthy adult population based on the 24-hour urine collection were included. Measured salt intake was extracted and compared with the GBD estimates. Of the 115 identified studies assessed for eligibility, 13 studies were included: Four studies were from Europe, and one each from the United States, Canada, Benin, India, Samoa, Fiji, Barbados, Australia, and New Zealand. Mean daily salt intake ranged from 6.75 g/d in Barbados to 10.66 g/d in Portugal. Measured mean population salt intake in Italy, England, Canada, and Barbados was lower, and in Fiji, Samoa, and Benin was higher, in recent surveys compared to the GBD 2010 estimates. Despite global targets to reduce population salt intake, only 13 countries have published nationally representative salt intake data since the GBD 2010 study. In all countries, salt intake levels remain higher than the World Health Organization's recommendation, highlighting the need for additional global efforts to lower salt intake and monitor salt reduction strategies.

Urinary Cell-Free DNA: Isolation, Quantification, and Quality Assessment.

Urine cell-free DNA is an important source of diagnostic markers for different diseases (e.g., cancer and prenatal diagnosis). It is important to achieve a simple and fast protocol to maximize the recovery of DNA from urine supernatant and to assess its quality. Here we describe a simple approach from urine collection to DNA quality assessment for downstream analyses.

Inequalities in healthcare access: how a man with exstrophy in rural India coped.

We report a case of a 22-year-old man with adult exstrophy. The patient made a self-made urine collection device, which helped him to lead a normal life, carrying out his routine as well as occupational activities smoothly. This patient is a prime example of inequalities in healthcare distribution in low-income and middle-income countries. He was never taken to a proper medical centre to correct his condition nor was his mother ever given proper antenatal healthcare access. His background of being a poor person from rural India highlights the problems of inequalities in healthcare access.

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.

Impact of two-step urine culture ordering in the emergency department: a time series analysis.

BACKGROUND: Despite evidence against the use of antimicrobials for asymptomatic bacteriuria (ASB), they are frequently prescribed leading to unnecessary adverse events. Prior studies have shown that reducing unnecessary urine cultures (UCs) results in decreased antimicrobial utilisation for ASB. Emergency departments (EDs) submit the largest volume of UCs, yet efforts to limit overordering in this patient setting have had limited success. METHODS: A new two-step model of care for urine collection, using a novel UC collection container, was implemented in the ED of a large community hospital. The collection system contains a preservative allowing UCs to be held at room temperature for up to 48 hours before processing. UCs were collected by front-line staff, but only processed in the microbiology lab if requested by ED physicians after clinical assessment. RESULTS: Following implementation there was a decrease in the percentage of weekly ED visits associated with a processed UC (5.97% vs 4.68%, p<0.001), a decrease in the percentage of monthly ED visits requiring a callback for positive urine culture (1.84% to 1.12%, p<0.001) and a decrease in antimicrobial prescriptions for urinary indication among admitted patients (20.6% to 10.9%, p<0.01). There was a false omission rate of 1.35% (95% CI 0.7% to 2.2%), yet no identified cases of untreated urinary tract infection (UTI), or significant change in repeat ED visits or ED length of stay. CONCLUSIONS: Changing to two-step urine culture ordering in the ED resulted in a decrease in UCs processed, callbacks for positive results and antimicrobial use without evidence of untreated UTIs. This model of care has strong potential to improve the use of hospital resources while minimising detection and inappropriate treatment of ASB.

Assessment of dietary sodium intake using a food frequency questionnaire and 24-hour urinary sodium excretion: a systematic literature review.

Food frequency questionnaires (FFQs) are often used to assess dietary sodium intake, although 24-hour urinary excretion is the most accurate measure of intake. The authors conducted a systematic review to investigate whether FFQs are a reliable and valid way of measuring usual dietary sodium intake. Results from 18 studies are described in this review, including 16 validation studies. The methods of study design and analysis varied widely with respect to FFQ instrument, number of 24-hour urine collections collected per participant, methods used to assess completeness of urine collections, and statistical analysis. Overall, there was poor agreement between estimates from FFQ and 24-hour urine. The authors suggest a framework for validation and reporting based on a consensus statement (2004), and recommend that all FFQs used to estimate dietary sodium intake undergo validation against multiple 24-hour urine collections.

A pilot study on the utility of reduced urine collection frequency protocols for the assessment of reproductive hormones in adolescent girls.

BACKGROUND: The objectives of this study were to assess the feasibility of and compliance to collecting urine samples in pre- and postmenarcheal girls and to determine if a less than daily collection frequency was sufficient for assessing ovarian function. METHODS: Twenty-five postmenarcheal girls (11-17 years) collected samples using either a two or a three samples/week protocol during one menstrual cycle. Exposure and mean estrone-1-glucuronide (E1G) and pregnanediol glucuronide concentrations were calculated, and evidence of luteal activity (ELA) was evaluated. Sixteen premenarcheal girls (8-11 years) collected one sample/month for six consecutive months. Samples were analyzed for E1G concentration. Participant compliance was calculated using dates on the urine samples and paper calendars. RESULTS: Participants collecting three samples/week were more compliant to the protocol than those collecting two samples/week (83.6%±2.6% vs. 66.8%±6.6%; p=0.034). There were no differences (p>0.10) regarding paper calendar return (81.8%±12.2% vs. 92.9%±7.1%), recording menses (55.6%±17.6% vs. 92.3%±7.7%) or sample collection (88.9%±11.1% vs. 84.6%±10.4%) between the two protocols. The average cycle length was 30.5±1.3 days and 32% of cycles had ELA. The premenarcheal girls were 100% compliant to the protocol. Only 68.8% of participants returned the paper calendar and 81.8% of those participants recorded sample collection. The average E1G concentration was 15.9±3.8 ng/mL. CONCLUSIONS: Use of a less than daily collection frequency during one menstrual cycle in postmenarcheal, adolescent girls is feasible and provides informative data about ovarian function. Collection of one sample/month in premenarcheal girls is feasible and detects the expected low E1G concentrations. Alternate strategies to the use of a paper calendar should be considered.

Gelified Biofluids for High-Resolution Magic Angle Spinning 1H NMR Analysis: The Case of Urine.

In this letter, we propose an alternative, effective protocol for metabolomic characterization of biofluids based on their gelification and subsequent application of high-resolution magic angle spinning (HRMAS) 1H nuclear magnetic resonance (NMR). The sample handling is very rapid and reproducible, and much less than 40 µL of neat urine are needed to obtain a sample. Our results indicate that the HRMAS spectra of gelified urine encompass all metabolites in the NMR fingerprint, as observed by solution NMR. The proposed approach can be efficiently integrated into the NMR based metabolomics analyses routines: multivariate statistical analysis of both solution and HRMAS data produced very similar statistical models, with high classification accuracy. One of the key advantages offered by the gelification approach is the improved short-term (up to 24 h) preservation of nonfrozen HRMAS NMR gel urine samples compared to the solution samples, which could lead to an alternative way for transportation or domestic collection of biofluids, without the need of cold-storage and reducing the risks of leakage.

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness.

BACKGROUND: It is not clear which young children presenting acutely unwell to primary care should be investigated for urinary tract infection (UTI) and whether or not dipstick testing should be used to inform antibiotic treatment. OBJECTIVES: To develop algorithms to accurately identify pre-school children in whom urine should be obtained; assess whether or not dipstick urinalysis provides additional diagnostic information; and model algorithm cost-effectiveness. DESIGN: Multicentre, prospective diagnostic cohort study. SETTING AND PARTICIPANTS: Children < 5 years old presenting to primary care with an acute illness and/or new urinary symptoms. METHODS: One hundred and seven clinical characteristics (index tests) were recorded from the child's past medical history, symptoms, physical examination signs and urine dipstick test. Prior to dipstick results clinician opinion of UTI likelihood ('clinical diagnosis') and urine sampling and treatment intentions ('clinical judgement') were recorded. All index tests were measured blind to the reference standard, defined as a pure or predominant uropathogen cultured at ≥ 10(5) colony-forming units (CFU)/ml in a single research laboratory. Urine was collected by clean catch (preferred) or nappy pad. Index tests were sequentially evaluated in two groups, stratified by urine collection method: parent-reported symptoms with clinician-reported signs, and urine dipstick results. Diagnostic accuracy was quantified using area under receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) and bootstrap-validated AUROC, and compared with the 'clinician diagnosis' AUROC. Decision-analytic models were used to identify optimal urine sampling strategy compared with 'clinical judgement'. RESULTS: A total of 7163 children were recruited, of whom 50% were female and 49% were < 2 years old. Culture results were available for 5017 (70%); 2740 children provided clean-catch samples, 94% of whom were ≥ 2 years old, with 2.2% meeting the UTI definition. Among these, 'clinical diagnosis' correctly identified 46.6% of positive cultures, with 94.7% specificity and an AUROC of 0.77 (95% CI 0.71 to 0.83). Four symptoms, three signs and three dipstick results were independently associated with UTI with an AUROC (95% CI; bootstrap-validated AUROC) of 0.89 (0.85 to 0.95; validated 0.88) for symptoms and signs, increasing to 0.93 (0.90 to 0.97; validated 0.90) with dipstick results. Nappy pad samples were provided from the other 2277 children, of whom 82% were < 2 years old and 1.3% met the UTI definition. 'Clinical diagnosis' correctly identified 13.3% positive cultures, with 98.5% specificity and an AUROC of 0.63 (95% CI 0.53 to 0.72). Four symptoms and two dipstick results were independently associated with UTI, with an AUROC of 0.81 (0.72 to 0.90; validated 0.78) for symptoms, increasing to 0.87 (0.80 to 0.94; validated 0.82) with the dipstick findings. A high specificity threshold for the clean-catch model was more accurate and less costly than, and as effective as, clinical judgement. The additional diagnostic utility of dipstick testing was offset by its costs. The cost-effectiveness of the nappy pad model was not clear-cut. CONCLUSIONS: Clinicians should prioritise the use of clean-catch sampling as symptoms and signs can cost-effectively improve the identification of UTI in young children where clean catch is possible. Dipstick testing can improve targeting of antibiotic treatment, but at a higher cost than waiting for a laboratory result. Future research is needed to distinguish pathogens from contaminants, assess the impact of the clean-catch algorithm on patient outcomes, and the cost-effectiveness of presumptive versus dipstick versus laboratory-guided antibiotic treatment. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Comparison of urine collection methods for albuminuria assessment in young children.

Cotton wool or pantyliners placed in a diaper can be used as urine collection devices for albuminuria measurements in young, not continent children. We tested a new collection method (PeeSpot(R)) for its analytical performance, and compared it with the pantyliner technique. Eighty-one urine samples with a wide range of albuminuria were pipetted on the pantyliner and PeeSpot in duplicate. These were incubated for 3h at 37°C (simulating the time a toddler wears a diaper), and subsequently 72h at room temperature (simulating transport to a central laboratory). Urine was extracted by centrifugation and albumin concentration (UAc) was measured. UAC measured by the two methods was compared with UAC in an unprocessed reference aliquot stored for 75h at 4°C. Bias (mean percentage UAC difference between test and reference), precision (interquartile range of the UAC difference) and accuracy (proportion of samples within 30% of reference UAC) were calculated. Median UAC in the reference aliquot was 66.0mg/L [IQR 25.0-211.0], pantyliner 32.0mg/L [4.7-165.0; P<0.001 vs reference], and PeeSpot 61.0mg/L [27.0-216.0; P=0.84 vs reference]. Bias, precision and accuracy in pantyliner were -34.2%, 31.3mg/L and 48.1%; in PeeSpot 3.3%, 5.0mg/L and 96.3%. Passing-Bablok regression and Bland-Altman plot showed an underestimation for the pantyliner but not for the PeeSpot. The PeeSpot is an accurate and precise tool for collecting urine for albumin measurement in young children and should be preferred over the alternative cotton wool collection technique.

Validation and Assessment of Three Methods to Estimate 24-h Urinary Sodium Excretion from Spot Urine Samples in Chinese Adults.

24-h urinary sodium excretion is the gold standard for evaluating dietary sodium intake, but it is often not feasible in large epidemiological studies due to high participant burden and cost. Three methods--Kawasaki, INTERSALT, and Tanaka--have been proposed to estimate 24-h urinary sodium excretion from a spot urine sample, but these methods have not been validated in the general Chinese population. This aim of this study was to assess the validity of three methods for estimating 24-h urinary sodium excretion using spot urine samples against measured 24-h urinary sodium excretion in a Chinese sample population. Data are from a substudy of the Prospective Urban Rural Epidemiology (PURE) study that enrolled 120 participants aged 35 to 70 years and collected their morning fasting urine and 24-h urine specimens. Bias calculations (estimated values minus measured values) and Bland-Altman plots were used to assess the validity of the three estimation methods. 116 participants were included in the final analysis. Mean bias for the Kawasaki method was -740 mg/day (95% CI: -1219, 262 mg/day), and was the lowest among the three methods. Mean bias for the Tanaka method was -2305 mg/day (95% CI: -2735, 1875 mg/day). Mean bias for the INTERSALT method was -2797 mg/day (95% CI: -3245, 2349 mg/day), and was the highest of the three methods. Bland-Altman plots indicated that all three methods underestimated 24-h urinary sodium excretion. The Kawasaki, INTERSALT and Tanaka methods for estimation of 24-h urinary sodium excretion using spot urines all underestimated true 24-h urinary sodium excretion in this sample of Chinese adults. Among the three methods, the Kawasaki method was least biased, but was still relatively inaccurate. A more accurate method is needed to estimate the 24-h urinary sodium excretion from spot urine for assessment of dietary sodium intake in China.

Iodine status assessment in children: spot urine iodine concentration reasonably reflects true twenty-four-hour iodine excretion only when scaled to creatinine.

BACKGROUND: Currently, the measurement of urinary iodine concentration (UIC, µg/L) is the recommended parameter to assess iodine status, however, the dependency of UIC on urine volume may limit its use as an accurate parameter for monitoring iodine status in populations. Therefore, our objective was to compare two approaches for the assessment of urinary iodine excretion in spot urine samples: UIC (µg/L) and a creatinine-scaled estimate of 24-hour iodine excretion (est24h-UIEcrea [µg/d]) against actually measured 24-hour urinary iodine excretion rates (24h-UIE, µg/d). METHODS: Urinary iodine and creatinine were measured both in 24-hour urine samples and parallel collected spot urine samples from 180 healthy participants of the DONALD Study, aged 6-18 years. 24h-UIE was used as quasi-reference for actual iodine status. Published 24-hour creatinine reference values served to calculate est24h-UIEcrea. Correlation analysis, cross-classifications, and Bland-Altman plots were used to evaluate agreement between the different assessment approaches. RESULTS: Correlation coefficients of 24h-UIE with UIC (r=0.12, r=0.22; p=n.s.) were substantially weaker than with est24h-UIEcrea (r=0.41, r=0.47; p<0.001) in the 6-12 year old and 13-18 year old groups, respectively. Cross-classification into opposite quartiles by UIC was 7% (6-12 year old group) and 15% (13-18 year old group) versus 5% and 3% by est24h-UIEcrea, respectively. Bland-Altman plots indicated greater deviation from 24h-UIE for the UIC versus the est24h-UIEcrea approach. CONCLUSION: Our findings in children and adolescents clearly show a better comparability of real 24h-UIE with est24h-UIEcrea than with UIC. Whenever highest possible validity is required for iodine status assessment from spot urine sampling, the determination of est24h-UIEcrea appears to be the more accurate monitoring approach.

Reductions in urinary collection frequency for assessment of reproductive hormones provide physiologically representative exposure and mean concentrations when compared with daily collection.

OBJECTIVE: To determine if reducing the frequency of urinary sample collection from daily to 5, 3, or 2 days per week during a menstrual cycle or 28-day amenorrheic monitoring period provide accurate representations of the reproductive hormone metabolites estrone-1-glucuronide (E1G) and pregnanediol glucuronide (PdG) exposure and mean concentrations. METHODS: Exercising women presenting with eumenorrhea or exercise-associated menstrual disturbances collected daily urine samples for the assessment of E1G and PdG concentrations. After enzyme immunoassay analysis of the daily samples, E1G and PdG data were systematically removed from each menstrual cycle or amenorrheic monitoring period to mimic three reduced collection frequencies, representing 5, 3, and 2 days per week. Exposure and mean concentration were calculated for both hormones and all four urinary collection frequencies. RESULTS: E1G and PdG exposure and mean cycle concentrations derived from reduced collection frequencies were not different from daily collection (P > 0.05), independent of whether menstrual cycles and monitoring periods were analyzed together or separately. Bland-Altman analysis indicated acceptable agreement between each reduced collection frequency and daily collection. CONCLUSIONS: Compared with daily urinary collection, a reduced collection frequency of 5, 3, or 2 days each week provides accurate E1G and PdG profiles of collection periods of various lengths and types of menstrual function. Reduction of urinary sample collection frequency may enable researchers to reduce participant burden and costs, increase compliance, and study a wider range of study populations.

Spot Urine Concentrations Should Not be Used for Hydration Assessment: A Methodology Review.

A common practice in sports science is to assess hydration status using the concentration of a single spot urine collection taken at any time of day for comparison against concentration (specific gravity, osmolality, color) thresholds established from first morning voids. There is strong evidence that this practice can be confounded by fluid intake, diet, and exercise, among other factors, leading to false positive/negative assessments. Thus, the purpose of this paper is to provide a simple explanation as to why this practice leads to erroneous conclusions and should be curtailed in favor of consensus hydration assessment recommendations.

Assessment concordance and predictive validity of self-report and biological assay of cocaine use in treatment trials.

BACKGROUND AND OBJECTIVES: Cocaine use during randomized clinical trials (RCTs) is typically assessed by participant self-report or biological assay (eg, urinalysis). There have been few direct comparisons of these assessment methods to investigate their concordance and their predictive validity for cocaine use and psychosocial outcomes following treatment completion. METHOD: In a combined sample of 380 participants from 5 cocaine RCTs, the concordance between cocaine use assessment methods was examined. Sequential multiple linear and logistic regression models evaluated the predictive validity of two assessment methods for cocaine use and psychosocial outcomes assessed at 1, 3, 6, and 12 months after treatment. RESULTS: Concordance for self-report and urinalysis indicators of cocaine use was high within-treatment (k = 0.72) and moderate during follow-up (k = 0.51). Rates of concordance were higher in studies using test cups with immediate urinalysis results. Regression analyses indicated that self-report data within-treatment predicted self-reported cocaine use at all post-treatment points (ß 0.22-0.30, p < .01), while urinalysis results within-treatment predicted urinalysis results at 1, 3, and 6 months post-treatment (OR 3.92-20.99, p < .05). Cocaine-positive urinalyses within-treatment were negatively associated with a composite "good outcome" indicator at 1 and 3 months post-treatment (OR 0.17-0.32, p < .05). DISCUSSION AND CONCLUSIONS: These results suggest a significant role of method variance in predicting post-treatment outcomes from within-treatment cocaine use indices. SCIENTIFIC SIGNIFICANCE: Results support recommendations that cocaine treatment trials should include both biological assay and self-report assessment. Test cups may facilitate increased self-report accuracy.