Risk of bias in cross-sectional studies: Protocol for a scoping review of concepts and tools.

Cross-sectional studies are commonly used to study human health and disease, but are especially susceptible to bias. This scoping review aims to identify and describe available tools to assess the risk of bias (RoB) in cross-sectional studies and to compile the key bias concepts relevant to cross-sectional studies into an item bank. Using the JBI scoping review methodology, the strategy to locate relevant RoB concepts and tools is a combination of database searches, prospective review of PROSPERO registry records; and consultation with knowledge users and content experts. English language records will be included if they describe tools, checklists, or instruments which describe or permit assessment of RoB for cross-sectional studies. Systematic reviews will be included if they consider eligible RoB tools or use RoB tools for RoB of cross-sectional studies. All records will be independently screened, selected, and extracted by one researcher and checked by a second. An analytic framework will be used to structure the extraction of data. Results for the scoping review are pending. Results from this scoping review will be used to inform future selection of RoB tools and to consider whether development of a new RoB tool for cross-sectional studies is needed.

Effects of caffeinated energy drinks on cardiovascular responses during exercise in healthy adults: a systematic review and meta-analysis of randomized controlled trials.

The impact of caffeinated energy drinks (CEDs) on the cardiovascular (CV) response to exercise has not been well described. A systematic review and meta-analysis was conducted on the acute effects of CEDs on CV responses during dynamic, aerobic exercise in 296 healthy adult males (224) and females (72) in 21 randomized controlled trials. During exercise, there was an increase in heart rate (HR) (mean difference (MD), 2.86 bpm, 95% CI, 2.39-3.34 bpm, I2 = 0%, p < 0.00001), and systolic blood pressure (SBP) (MD, 9.02 mm Hg, 95% CI, 4.25-13.79 mm Hg, I2 = 0%, p = 0.0002) with consumption of CEDs, compared with controls, but diastolic blood pressure was similar. Insufficient data were available to evaluate rate pressure product (HR × SBP) and exercise-induced arrhythmia. Though changes to HR during exercise were modest, the significant increase in exercise SBP highlights the importance of directly assessing CV effects of CEDs with exercise, especially in individuals prone to hypertension. Novelty: Exercise SBP in healthy adults is significantly increased during exercise with the consumption of CEDs compared with controls, despite limited data. The direct assessment of CV effects of CEDs with exercise highlights the particular relevance to individuals prone to hypertension.

NUQUEST-NUtrition QUality Evaluation Strengthening Tools: development of tools for the evaluation of risk of bias in nutrition studies.

BACKGROUND: Dietary exposure assessments are a critical issue in evaluating human nutrition studies; however, nutrition-specific criteria are not consistently included in existing bias assessment tools. OBJECTIVES: Our objective was to develop a set of risk of bias (RoB) tools that integrated nutrition-specific criteria into validated generic assessment tools to address RoB issues, including those specific to dietary exposure assessment. METHODS: The Nutrition QUality Evaluation Strengthening Tools (NUQUEST) development and validation process included 8 steps. The first steps identified 1) a development strategy; 2) generic assessment tools with demonstrated validity; and 3) nutrition-specific appraisal issues. This was followed by 4) generation of nutrition-specific items and 5) development of guidance to aid users of NUQUEST. The final steps used established ratings of selected studies and feedback from independent raters to 6) assess reliability and validity; 7) assess formatting and usability; and 8) finalize NUQUEST. RESULTS: NUQUEST is based on the Scottish Intercollegiate Guidelines Network checklists for randomized controlled trials, cohort studies, and case-control studies. Using a purposive sample of 45 studies representing the 3 study designs, interrater reliability was high (Cohen's κ: 0.73; 95% CI: 0.52, 0.93) across all tools and at least moderate for individual tools (range: 0.57-1.00). The use of a worksheet improved usability and consistency of overall interrater agreement across all study designs (40% without worksheet, 80%-100% with worksheet). When compared to published ratings, NUQUEST ratings for evaluated studies demonstrated high concurrent validity (93% perfect or near-perfect agreement). Where there was disagreement, the nutrition-specific component was a contributing factor in discerning exposure methodological issues. CONCLUSIONS: NUQUEST integrates nutrition-specific criteria with generic criteria from assessment tools with demonstrated reliability and validity. NUQUEST represents a consistent and transparent approach for evaluating RoB issues related to dietary exposure assessment commonly encountered in human nutrition studies.

Caffeinated energy drinks in the Canadian context: health risk assessment with a focus on cardiovascular effects.

In Canada, caffeinated energy drinks (CEDs) currently sold under Temporary Marketing Authorizations must meet strict eligibility criteria. These criteria, which include compositional and labelling requirements, were developed based on the outcome of a health risk assessment conducted by Health Canada (HC) in 2013. HC updated its assessment by reviewing new information with the focus on potential cardiovascular effects associated with the consumption of CEDs available for sale in Canada. Due to limited data on CED consumption among Canadians to derive accurate exposure information, the composition of a typical CED was characterized to assess the potential effects of single ingredients and synergistic interactions between ingredients on the cardiovascular system. Surveillance data on potential adverse effects related to CED consumption was also analyzed. After extensive review, HC's updated assessment confirms the current risk management approach for CEDs is health protective for Canadian consumers, including the potential for cardiovascular effects. The available evidence supports that moderate consumption (up to 500 mL per day) of a typical CED authorized for sale in Canada is safe for the general population of healthy adults and adolescents. It also re-confirms that vulnerable sub-populations (i.e., children, pregnant and/or breastfeeding women, and caffeine-sensitive individuals) should not consume CEDs. Novelty: Consumption up to 500 mL per day of a typical CED is not associated with an increased risk of cardiovascular effects. Children, pregnant and/or breastfeeding women, and caffeine-sensitive individuals should not consume CEDs.

Method comparison for 241Am emergency urine bioassay.

241Am is one of the high-risk radionuclides that might be used in a terrorist attack. 241Am in urine bioassay can identify the contaminated individuals who need immediate medical intervention and decontamination. This paper compares three methods for the measurement of 241Am in urine, namely liquid scintillation counting (LSC), inductively coupled plasma mass spectrometry (ICP-MS) and gamma spectrometry (GS), at two levels, 20 and 2 Bq l(-1). All three methods satisfied the ANSI N13.30 radio-bioassay criteria for accuracy and repeatability. ICP-MS offered the best sensitivity and fastest sample turnaround; however, the ICP-MS system used in this work may not be available in many bioassay laboratories. LSC and GS are more commonly available instruments. GS requires minimal or no sample preparation, which makes it a good candidate method. Moreover, the sample throughput can be significantly improved if the GS and LSC methods are automated.

Effect of calcium on iron absorption in women with marginal iron status.

We measured non-haem Fe absorption with and without added Ca in a short-term feeding study, in thirteen women with marginal Fe status, by the use of a double stable isotope technique. Supplementing 500 mg Ca as calcium carbonate significantly (P = 0.0009) reduced Fe absorption from a single meal from 10.2 % (range 2.2-40.6) to 4.8 % (range 0.7-18.9). A significant inverse correlation in the absence ( - 0.67, P = 0.010) and presence ( - 0.58, P = 0.037) of Ca, respectively, was found between Fe absorption and Fe stores measured by serum ferritin (SF). Wide variation in Fe absorption was observed between individuals in the absence and in the presence of Ca, despite pre-selection of participants within a relatively narrow range of iron stores (SF concentrations). Correction of Fe absorption data based on group mean SF was not found to be useful in reducing the inter-individual variability in iron absorption. It appears that selecting a study group with a narrow initial range of Fe stores does not necessarily reduce the inter-individual variability in Fe bioavailability measurements. These results support the hypothesis that body Fe stores, although an important determinant of dietary Fe absorption, are not the main factor that determines Fe absorption under conditions of identical dietary intake in subjects with low Fe stores.

Determination of total iodine in food samples using inductively coupled plasma-mass spectrometry.

A method was developed and validated for the extraction and determination of total iodine (I) in food composite samples, representing different foods available on the Canadian market, by inductively coupled plasma-mass spectrometry (ICP-MS). Prior to analysis, samples were digested in a closed microwave system using a mixture of nitric acid and perchloric acid. The detection limit for iodine determination was 29 nglg and precisions of 10 and 1.3% were obtained for 10 replicate measurements of 100 and 1000 ng/g standards, respectively. The method was validated using Certified Reference Materials and spike recovery measurements in food samples and was applied for the determination of iodine in a variety of food composite samples from the Canadian Total Diet Study. The high sample throughput of ICP-MS makes the method suitable for analysis of large numbers of food samples with varying matrixes, such as for Total Diet Studies.

Isotope ratio measurements of iron in blood samples by multi-collector ICP-MS to support nutritional investigations in humans.

With the perspective of embarking on a human study using a double iron (Fe) stable isotope tracer protocol to assess iron bioavailability, investigations were conducted on Fe isotope ratios in blood samples using a VG Axiom Multi-collector ICP-MS. The factors affecting the precision and accuracy of Fe isotopic ratios, such as spectral- and matrix-induced interferences and Fe recoveries from sample preparation, have been identified and optimized. Major polyatomic interferences (e.g., Ar-O, Ar-OH, and FeH) were significantly reduced by using an Aridus nebulizer and desolvating system. Isobaric metal (e.g., (54)Cr(+) on (54)Fe(+) and (58)Ni(+) on (58)Fe(+)) interferences and Ca-oxides and hydroxides were quantitatively removed during chemical purification of blood samples and selective isolation of Fe by anion-exchange resin, after mineralization of the blood samples by microwave digestion. Quantitative recoveries of Fe from different steps of sample preparation were verified using whole blood reference material. Fe isotopic compositions of the samples were corrected for instrumental mass bias by the standard-sample bracketing method using the certified reference standard IRMM-014. External precisions on the order of 0.008-0.05 (% RSD), 0.007-0.015 (% RSD), and 0.03-0.09 (% RSD) were obtained for (54)Fe/(56)Fe, (57)Fe/(56)Fe, and (58)Fe/(56)Fe, respectively, in the blood for three replicate measurements. The level of precision obtained in this work enables the detection of low enrichments of Fe in blood, which is highly desired in nutrition tracer studies.

Determination of trace elements in natural waters by inductively coupled plasma time of flight mass spectrometry after flow injection preconcentration in a knotted reactor.

A flow injection on-line sorption system was developed for the separation and preconcentration of traces of Ag, Cd, Co, Ni, Pb, U and Y from natural water samples with subsequent detection by ICP TOF MS. Simultaneous preconcentration of the analytes was achieved by complexation with the chelating reagent 1-phenyl-3-methyl-4-benzoylpyrazol-5-one immobilized on the inner walls of a (200cm x 0.5mm) PTFE knotted reactor. The analytes were eluted and transported to an axial ICP TOF MS system with 1% (v/v) HNO(3) containing 0.3microg l(-1) of Rh as an internal standard using ultrasonic nebulization. The detection limits (3sigma) varied from 0.3ng l(-1) for Y to 15.2ngl(-1) for Ni and the precision (R.S.D.) was better than 4%. Using a loading time of 90s and a sample flow rate of 4.5ml min(-1), enhancement factors of 3-14 were obtained for the different analytes in comparison with their direct determination by ICP TOF MS with ultrasonic nebulization without preconcentration. The accuracy of the method was demonstrated by analysis of water based certified reference materials.

Flow-injection technique for determination of uranium and thorium isotopes in urine by inductively coupled plasma mass spectrometry.

A sensitive and efficient flow-injection (FI) preconcentration and matrix-separation technique coupled to sector field ICP-mass spectrometry (SF-ICP-MS) has been developed and validated for simultaneous determination of ultra-low levels of uranium (U) and thorium (Th) in human urine. The method is based on selective retention of U and Th from a urine matrix, after microwave digestion, on an extraction chromatographic TRU resin, as an alternative to U/TEVA resin, and their subsequent elution with ammonium oxalate. Using a 10 mL sample, the limits of detection achieved for 238U and 232Th were 0.02 and 0.03 ng L(-1), respectively. The accuracy of the method was checked by spike-recovery measurements. Levels of U and Th in human urine were found to be in the ranges 1.86-5.50 and 0.176-2.35 ng L(-1), respectively, well in agreement with levels considered normal for non-occupationally exposed persons. The precision obtained for five replicate measurements of a urine sample was 2 and 3% for U and Th, respectively. The method also enables on-line measurements of the 235U/238U isotope ratios in urine. Precision of 0.82-1.04% (RSD) was obtained for 235U/238U at low ng L(-1) levels, using the FI transient signal approach.