Significant Proportional Bias Research Articles

Validation of a quantitative web-based food frequency questionnaire to assess dietary intake in the adult Emirati population.

Background and objectiveA culture-specific web-based food frequency questionnaire (FFQ) to assess dietary intake in the United Arab Emirates (UAE) adult population was developed using data from the 2009–2010 national nutrition survey. The objective of this study was to assess the relative validity of the newly developed FFQ for use in the adult Emirati population (AE-FFQ), which contained a list of 139 food lines.MethodsA convenient sample of 60 (36 females and 24 males) adult Emiratis completed 3 non-consecutive 24HRs over a period of one month, followed by the AE-FFQ, which assessed the intake over the previous month. Relative validity was evaluated by comparing nutrient and food group intakes from the AE-FFQ with the average three 24HRs using Wilcoxon signed-rank tests, Spearman’s correlation coefficients (CC), Bland-Altman analysis, and cross-classification.ResultsThe AE-FFQ overestimated energy and most nutrients and food groups. Bland–Altman analysis showed significant proportional bias between the 2 methods. Deattenuated energy-adjusted Spearman correlation coefficients were poor to good ranging from 0.06 (iron) to 0.62 (fiber) for nutrients, 0.39 median value, and from –0.01 (cruciferous vegetables) to 0.64 (eggs) for food groups, 0.41 median value. A fairly acceptable agreement was obtained, with correct classification into the same or adjacent quartile ranging from 34% (vitamin B12) to 78% (pyridoxine), median 69% for nutrients and from 55% (diet soft drinks) to 87% (soft drinks), median 67% for food groups.ConclusionsThe AE-FFQ is an acceptable tool for ranking UAE adults (aged 18 to 50) according to their dietary intake to investigate the role of Emirati dietary patterns on health and disease. Caution is needed for assessing absolute intake, however, given the bias observed in assessing group-level agreement.

Comparative quantification of focal and diffuse visual field loss by the SPARK Precision threshold algorithm and SITA

PurposeThe aims of this paper were to examine focal and diffuse visual field loss in terms of threshold agreement between the widely used SITA Standard Humphrey Field Analyser (HFA) threshold algorithm with the SPARK Precision algorithm (Oculus Twinfield 2).MethodsA total of 39 treated glaucoma patients (34 primary open angle and 5 primary angle closure glaucoma) and 31 cataract patients without glaucoma were tested in succession with the Oculus Twinfield 2 (Oculus Optikgeräte GmbH, Wetzlar, Germany) using the SPARK Precision algorithm and with the HFA 3 (Carl Zeiss Meditec, Dublin, CA) using the 30–2 SITA Standard algorithm.ResultsSPARK Precision required around half the testing time of SITA Standard. There was a good correlation between the MS of the two threshold algorithms but MD and PSD were significantly less severe with SPARK Precision in both glaucoma (focal field loss) and cataract (diffuse field loss) groups (p < 0.001). There was poor agreement for all global indices (MS, MD and PSD) between the two algorithms and there was a significant proportional bias of MD in the glaucoma group and PSD in both glaucoma and cataract groups. The pointwise sensitivity analysis yielded higher threshold estimates in SPARK Precision than in SITA Standard in the nasal field. Classification of glaucoma severity using AGIS was significantly lower with SPARK Precision compared to SITA Standard (p < 0.001).ConclusionSITA renders deeper defects than SPARK. Compared to the SITA Standard threshold algorithm, SPARK Precision cannot quantify early glaucomatous field loss. This may be due to the mathematical linear interpolation of threshold sensitivity or deeper scotomas due to the plateau effect caused by the reduced dynamic range of the Twinfield 2 perimeter. Although not of clinical significance in early glaucoma, the plateau effect may hinder the long-term follow-up of patients during disease progression.

Verification of Atellica 1500 and comparison with Iris urine analyser and urine culture.

IntroductionThe aims of study were to assess: 1) performance specifications of Atellica 1500, 2) comparability of Atellica 1500 and Iris, 3) the accuracy of both analysers in their ability to detect bacteria.Materials and methodsCarryover, linearity, precision, reproducibility, and limit of blank (LoB) verification were evaluated for erythrocyte and leukocyte counts. ICSH 2014 protocol was used for estimation of carryover, CLSI EP15-A3 for precision, and CLSI EP17 for LoB verification. Comparison for quantitative parameters was evaluated by Bland-Altman plot and Passing-Bablok regression. Qualitative parameters were evaluated by Weighted kappa analysis. Sixty-five urine samples were randomly selected and sent for urine culture which was used as reference method to determine the accuracy of bacteria detection by analysers.ResultsAnalytical specifications of Atellica 1500 were successfully verified. Total of 393 samples were used for qualitative comparison, while 269 for sediment urinalysis. Bland-Altman analysis showed statistically significant proportional bias for erythrocytes and leukocytes. Passing-Bablok analysis for leukocytes pointed to significant constant and minor proportional difference, while it was not performed for erythrocytes due to significant data deviation from linearity. Kappa analysis resulted in the strongest agreements for pH, ketones, glucose concentrations and leukocytes, while the poorest agreement for bacteria. The sensitivity and specificity of bacteria detection were: 91 (59-100)% and 76 (66-87)% for Atellica 1500 and 46 (17-77)% and 96 (87-100)% for Iris.ConclusionThere are large differences between Atellica 1500 and Iris analysers, due to which they are not comparable and can not be used interchangeably. While there was no difference in specificity of bacteria detection, Iris analyser had greater sensitivity.

The accuracy and reliability of WebCeph for cephalometric analysis

ObjectiveThis study compares the accuracy and reliability of WebCeph (web-based program for cephalometric analysis) with the AutoCAD computer software. Materials and methodsA sample of pretreatment digital lateral cephalograms of 50 orthodontic patients was analysed with WebCeph and AutoCAD software (as a standard measure). On each cephalogram, 17 landmarks and 11 measurements were marked and performed as skeletal, dental, and soft–tissue parameters. We used six angular and five linear measurements. A paired t-test was used to assess the systematic bias. The intraclass correlation coefficient (ICC) and Bland–Altman plot with linear regression analysis were used to assess the agreement between the two methods. ResultsThere was adequate reproducibility for the measurements with both WebCeph and AutoCAD. The paired t-test showed statistically significant differences for five angular and two linear measurements (P < 0.05). The ICC test between WebCeph and AutoCAD revealed very good to excellent agreement for all measurements, except for the lower incisor to mandibular plane angle. The Bland–Altman plot visually showed a relatively acceptable limit of agreement for three angular and two linear measurements only, and the linear regression analysis revealed a significant proportional bias between the two methods for four angles and the upper lip-Esthetic line (U Lip-E Line). The systematic bias and level of agreement improved with the use of the semi-automatic WebCeph. ConclusionsDifferent problems, such as poor landmark identification/soft tissue tracing and inconsistency of measurements, are inherent to the automatic WebCeph. The semi-automatic WebCeph can overcome some limitations of the automatic WebCeph; however, it should be used for cephalometric analysis with a great deal of caution.

Measuring Activated Clotting Time during Cardiac Catheterization and PCI: The Effect of the Sampling Site.

Results In 100 patients (mean age 67.1, 65% male), no significant differences were observed in ACT values obtained from the guiding catheter and arterial sheath (mean difference (MD) −18.3 s; standard deviation (SD) 96 s; P=0.067). Contrarily, ACT values obtained from the intravenous line were significantly lower as compared to values obtained from the guiding catheter (MD 25.7 s; SD 75.5; P=0.003) and arterial sheath (MD 39 s; SD 102.8; P < 0.001). Furthermore, ACT measurements from the arterial sheath showed a statistically significant proportional bias when compared to the other sampling sites (sheath vs. catheter, r = 0.761, P=0.001; sheath vs. IVL, r = 1.013, P < 0.001). Conclusions The present study shows statistical significance and possibly clinically relevant variations between ACT measurements from different sample sites. Bias in ACT measurements may be minimized by using uniform protocols for ACT measurement during cardiac catheterization.

Comparison of selected serum biochemistry measurements between the Nova Prime Plus VET, Nova pHOx Ultra, and Beckman Coulter AU680 analyzers in dogs.

Blood gas chemistry analyzers typically produce results faster and use smaller sample volumes than reference chemistry analyzers. However, results may not be comparable between blood gas chemistry analyzers and reference chemistry analyzers or between different models of blood gas chemistry analyzers. This could suggest the use of separate reference intervals and, thus, has implications when making clinical decisions. We aimed to perform method comparison studies to evaluate selected canine serum biochemical values obtained using the Nova Stat Profile Prime Plus VET (Prime Plus VET), Stat Profile Nova pHOx Ultra (Ultra), and Beckman Coulter AU680 (Beckman) analyzers. We hypothesized that the three analyzers would be identical within inherent imprecision. Jugular venous blood samples were collected from 103 endurance-trained sled dogs, and serum was harvested and stored for analysis. Results for serum chloride, potassium, sodium, creatinine, and urea nitrogen concentrations obtained from the Prime Plus VET and Ultra analyzers were compared with results from the Beckman analyzer, which was considered to be a reference method. Results for serum chloride, potassium, sodium, creatinine, urea nitrogen, and L-lactate concentrations obtained from the Prime Plus VET and Ultra analyzers were compared. Passing-Bablok regression and Bland-Altman plots were used for method comparison. Significant (P<0.05) constant or proportional bias was found for many analytes for all three method comparison studies. Due to the presence of statistically significant differences between all three analyzers that may be clinically relevant, it is recommended that reference intervals be created for new blood gas analyzers, even when similar methodologies are used.

Discrepancies between self-reported and device-measured sleep parameters in adults with multiple sclerosis.

Sleep problems are a common consequence of multiple sclerosis; however, there is limited evidence regarding the agreement between device-measured and self-reported sleep parameters in adults with multiple sclerosis. The present study examined the agreement between self-reported and device-measured parameters of sleep quality in a sample of adults with multiple sclerosis. Participants (n = 49) completed a 7-day sleep diary and wore a wrist-worn ActiGraph GT3×+ (ActiGraph Corp., Pensecola, FL) for seven consecutive nights to quantify self-reported and device-measured sleep parameters, respectively. There was a significant discrepancy between self-reported and device-measured parameters of total time in bed (mean difference = 19.8 [51.3] min), sleep onset latency (mean difference = 22.2 [19.5] min), and frequency of awakenings during the night (mean difference = 12.8 [6.8]). Intraclass correlation estimates indicated poor agreement between methods on most parameters, except for total time in bed (intraclass correlation = 0.80). Bland-Altman plots suggested that total time in bed and total sleep time had acceptable levels of agreement and linear regression analyses indicated that sleep onset latency (F = 113.91, B = -1.34, P < .001), number of awakenings (F = 543.34, B = 1.85, P < .001), and sleep efficiency (F = 18.39, B = -0.77, P < .001) had significant proportional bias. Our results draw attention to the discrepancies between sleep parameter measurements and highlight the importance of including both self-report and device-measured outcomes for a complete and accurate representation of sleep in adults with multiple sclerosis. Cederberg KLJ, Mathison BG, Schuetz ML, Motl RW. Discrepancies between self-reported and device-measured sleep parameters in adults with multiple sclerosis. J Clin Sleep Med. 2022;18(2):415-421.

Correlation between peripheral blood automated hematopoietic progenitor cell counts and flow cytometric CD34+ cell counts differs according to diagnosis in patients undergoing autologous peripheral blood stem cell transplantation.

An automated hematopoietic progenitor cell count measurement in Sysmex XN analyzer (XN-HPC) has been developed to assist flow cytometry CD34+ cell count measurement, which requires technical expertise and a long turnaround time. Here, we evaluated the correlation between XN-HPC count and flow cytometric CD34+ cell count in pre-harvest peripheral blood (PB) samples from patients undergoing autologous peripheral blood stem cell (PBSC) transplantation according to diagnosis and investigated the possible cause of the decreased correlation in plasma cell neoplasm patients. We retrospectively included 399 patient data that had matched PB XN-HPC count and CD34+ cell count of PB and apheresis product from Samsung Medical Center (SMC) and the Hematopoietic Stem Cell (HSC) registry. We assessed the diagnostic accuracy and the potential cutoff values of XN-HPC count for predicting adequate PBSC collection. The PB XN-HPC count was 1.6 and 1.3-fold higher than the CD34+ cell count in SMC (25.0 vs 15.9/μl) and the HSC registry (20.0 vs 15.2/μl), respectively. Overall the correlation between the PB XN-HPC and CD34+ cell count was moderate (SMC, r=0.71; HSC registry, r=0.66). A significant proportional and systemic bias with overestimation of XN-HPC count were noted in the plasma cell neoplasm patients in both SMC and the HSC registry. However, no significant difference in correlation was observed according to myeloma-related laboratory parameters in plasma cell neoplasm patients. Our results suggest that XN-HPC count should be interpreted cautiously in cancer patients undergoing autologous PBSC transplantation, especially in those with plasma cell neoplasm.

Performance of 3 mL versus 5 mL Discarded Volume for Blood Sampling from Central Venous Access Device.

Background Central venous access devices (CVAD) are an essential part of safe practices in critical care, which enable effective venous access and help in avoiding repeated venipuncture. Discard method is widely practiced for blood sampling. A single occasion of blood sampling may cause minimal blood loss; however, the cumulative volume sequential sampling may become clinically significant. The study aims to reduce diagnostic blood loss, ensuring that the subsequent blood sample is not diluted or contaminated by residual intraluminal fluid. Patients and Methods Within-subjects comparative design was adopted for 64 adult patients in the medical intensive care unit of a tertiary hospital. Two blood samples, using 3 mL and 5 mL discarded volume methods, were collected from each patient. Six serum parameters were measured on each of the paired samples and compared. Statistical Analysis Used Paired t -test and Wilcoxon signed rank test were used for comparing the two methods. Bland–Altman plot analysis and intraclass correlation were used for clinically meaningful analysis. Results When tested for fixed bias, there is no statistically significant difference between the methods. Potassium and creatinine levels showed significant proportional bias. The agreement limits of sodium, potassium, creatinine, and direct bilirubin were outside the clinically accepted interval, but the proportion of samples outside these intervals was less than 10%. All serum parameters showed excellent reliability, except for sodium which demonstrated good reliability. Conclusions The practice of discarding 3 mL of blood for discard method is suggested, instead of the standard 5 mL to reduce iatrogenic blood loss. Thus, nurses in critical care are uniquely positioned to limit the diagnostic blood loss while obtaining blood samples.

A technical and clinical evaluation of the new ThermoFisher BRAHMS unconjugated estriol and inhibin-A assays and their use in second trimester Down syndrome screening

To evaluate second-trimester Down syndrome screening performance of the new ThermoFisher BRAHMS GOLD unconjugated estriol (uE3) and inhibin-A assays. Serum samples were analyzed for levels of uE3 and inhibin-A using the ThermoFisher BRAHMS GOLD immunoanalyzer and compared to other platforms. Levels were transformed to multiples of the median (MoM) in unaffected pregnancies. Log10 MoM distributions in unaffected and Down syndrome pregnancies were assessed for central tendency (mean) and dispersion (SD). Empirical and estimated screening performances were determined. Correlation between BRAHMS and AutoDELFIA® uE3 and inhibin-A were 0.63 and 0.97, respectively, the respective mean difference was 31.3% [95%CI 50.2% to −112.8%] and −23.3% [95%CI −41.9% to −4.7%]. Passing–Bablok indicated significant systematic (−2.78 [95%CI −3.57 to −2.04]) and proportional bias (1.30 [95%CI 1.15 to −1.47]) between uE3 assays and significant proportional bias (0.71[95%CI 0.65–0.78]) between inhibin-A assays. The uE3 and inhibin-A log10 MoM distribution mean [SD] in unaffected and Down syndrome pregnancies were 0.0024 [SD = 0.2341] and −0.0001 [SD = 0.2078], and −0.2028 [SD = 0.2495] and 0.3645 [SD = 0.2576], respectively. The new BRAHMS uE3 and inhibin-A assays had an 81–83% detection rate for Trisomy21 for a 5% false-positive rate. The new BRAHMS assays achieved the expected screening performance provided the risk estimation model is adjusted to account for the higher BRAHMS uE3 MoM measurement distribution variance.

Comparison of a Point-of-Care Analyzer With a Chemiluminescent Immunoassay for Serum Progesterone Measurement in Breeding Management of the Bitch.

Accurate serum progesterone measurements for timing bitches during breeding management is critical for reproductive practice, especially as artificial insemination has become routine to facilitate breeding of animals that are geographically or temporally separated. To measure serum progesterone, chemiluminescent immunoassay (CLIA) has replaced radioimmunoassay as the current standard in the bitch due to its high correlation and increased practicality. In January 2019, a colorimetric point-of-care (POC) immunoassay for quantitative in-clinic canine serum progesterone measurements in <30 min was released. This study provides an independent comparison of the POC (Catalyst One, IDEXX) to the current industry standard, CLIA (Immulite-2000, Siemens). To assess inter-assay imprecision of POC and agreement of the POC and CLIA results, 100 canine serum samples were analyzed on three analyzers (POC-1, POC-2, and CLIA), of which, 74 (POC-1) and 75 (POC-2) results were within POCs' reportable range of 0.2–20 ng/mL and included in the study. To assess intra-assay imprecision, pooled canine serum samples at low (L1), intermediate (L2), and high (L3) progesterone concentrations were analyzed ten times each on POC-1 and CLIA. Relative to CLIA, POC values showed good correlation (POC-1, r2 = 0.9366; POC-2, r2 = 0.9438, P < 0.0001) and significant positive proportional bias at values >2 ng/mL. The POC inter-assay coefficients of variation (CVs) were 13.2% (0.2–2.9 ng/mL, 0.6–9.2 nmol/L, L1), 10.0% (3.0–9.9 ng/mL, 9.5–31.5 nmol/L, L2), 7.1% (10.0–20.0 ng/mL, 31.8–63.6 nmol/L, L3), and 11.2% (all samples). The intra-assay CVs for POC (L1, 15.3%; L2, 7.0%; L3, 4.7%) were higher than those for CLIA (L1, 5.89%; L2, 4.89%; L3, 3.44%). Based on the more rapid increase in serial serum progesterone concentrations in ovulating bitches and the greater imprecision of the POC, the clinical interpretations of serum progesterone measurements as they relate to canine breeding management should be made with caution.

Adaptation and validation of the Japanese version of the Spinal Cord Independence Measure (SCIM III) self-report.

Psychometric study, cross-sectional validation study. To adapt and validate the Japanese version of the Spinal Cord Independence Measure self-report (SCIM-SR). A spinal cord injury (SCI) rehabilitation facility in Japan. We adapted the SCIM-SR for the Japanese population by translating and validating the questionnaire in accordance with the international guidelines. Following this, we analyzed 100 inpatients with SCI. We evaluated their independence using the Japanese SCIM-SR, and compared the data with those assessed using the SCIM III by trained ward nurses. Spearman's rank correlation coefficients were 0.95 for the total score, 0.89 for self-care, 0.83 for respiration and sphincter management, and 0.89 for mobility subscores. The Bland-Altman analysis revealed no significant proportional bias (-0.02; 95% CI [-0.07, 0.06]), but a significant fixed bias (2; 95% CI [0.5, 3.5]). We did not identify any specific factor that affected the differences between SCIM III and SCIM-SR scores. Our study validated the Japanese version of SCIM-SR as a tool for the evaluation of the independence of persons with SCI, which could substitute SCIM III and help facilitate a deeper understanding of activities of daily living among patients with SCI.

The Single Assessment Numeric Evaluation (SANE) after anterior cervical discectomy and fusion: A pilot study

Study designRetrospective cohort. ObjectivesTo evaluate the single assessment numerical evaluation (SANE) as a patient reported outcomes measure (PROM) after anterior cervical discectomy and fusion (ACDF), by comparing to legacy measures. MethodsWe included all patients undergoing ACDF with at least one year of follow up with complete PROM data. Patients completed the Neck Disability Index (NDI), the RAND-36 and the EuroQual Five Dimension (EQ-5D) scale, as well as the one-question SANE, pre- and post-operatively. Validity of SANE compared with other PROMs was determined utilizing Pearson’s correlation (ρ), proportional bias (B), responsiveness, minimal clinically important difference (MCID) and agreement. ResultsSixty-nine patients were included. There were moderate-to-strong correlations at a minimum of one-year follow-up between the SANE and NDI (ρ = −0.73, P < 0.0001), RAND (ρ = 0.80, P < 0.0001), and EQ-5D (ρ = −0.66, P < 0.0001). No significant proportional bias was found for the SANE when compared to the RAND (B = 0.03, p = 0.99), NDI (B = −0.003, p = 0.99), or EQ-5D (B = −0.0007, p = 0.99). Responsiveness for SANE was statistically similar to all other PROMs. The MCID for SANE was determined to be 10.5, with 42% of patients achieving the MCID. Bland-Altman plots demonstrated high agreement between all PROMs. ConclusionWe found the SANE score provides clinically important patient outcomes data after ACDF, despite only requiring answering one question. The SANE performs comparably to more burdensome health questionnaires. The SANE score may offer spine surgeons the option to easily and quickly collect clinically relevant data on their surgical patients.

Echocardiographic Left Ventricular Mass Assessment: Correlation between 2D-Derived Linear Dimensions and 3-Dimensional Automated, Machine Learning-Based Methods in Unselected Patients.

A recently developed algorithm for 3D analysis based on machine learning (ML) principles detects left ventricular (LV) mass without any human interaction. We retrospectively studied the correlation between 2D-derived linear dimensions using the ASE/EACVI-recommended formula and 3D automated, ML-based methods (Philips HeartModel) regarding LV mass quantification in unselected patients undergoing echocardiography. We included 130 patients (mean age 60 ± 18 years; 45% women). There was only discrete agreement between 2D and 3D measurements of LV mass (r = 0.662, r2 = 0.348, p < 0.001). The automated algorithm yielded an overestimation of LV mass compared to the linear method (Bland–Altman positive bias of 13.1 g with 95% limits of the agreement at 4.5 to 21.6 g, p = 0.003, ICC 0.78 (95%CI 0.68−8.4). There was a significant proportional bias (Beta −0.22, t = −2.9) p = 0.005, the variance of the difference varied across the range of LV mass. When the published cut-offs for LV mass abnormality were used, the observed proportion of overall agreement was 77% (kappa = 0.32, p < 0.001). In consecutive patients undergoing echocardiography for any indications, LV mass assessment by 3D analysis using a novel ML-based algorithm showed systematic differences and wide limits of agreements compared with quantification by ASE/EACVI- recommended formula when the current cut-offs and partition values were applied.

Reliability and Validity of a Carbohydrate-Counting Knowledge Questionnaire for Young Australians With Type 1 Diabetes

ObjectiveTo test the reliability and validity of a carbohydrate-counting knowledge questionnaire in young Australians with type 1 diabetes mellitus (T1DM). MethodsChildren or young adults (<20 years) with T1DM, or their parents, completed the 72-item Australian PedCarbQuiz (AusPCQ), adapted from the American PedCarbQuiz, and an expert assessment of carbohydrate-counting knowledge. Responses were scored and summed (0–72, higher scores = greater knowledge). Internal reliability was assessed using Cronbach α, and relative validity using Spearman correlations (with HbA1c) and Bland-Altman analysis (with the expert assessment). ResultsAustralian PedCarbQuiz reliability (n = 44, mean score = 59.7 ± 5.6) was acceptable (α = 0.83). There was a lack of agreement (mean bias = 10.7, P = 0.008) and significant proportional bias between AusPCQ scores and expert assessments (β = −0.73 [95% confidence interval, −1.82 to −0.79]; P < 0.001). Conclusions and ImplicationsThe AusPCQ was shown to be reliable but not valid in a small sample. Testing in a larger sample is warranted.

Accuracy of wrist-worn heart rate monitors during physical therapy sessions among hemiparetic inpatients with stroke.

[Purpose] We aimed to examine the accuracy of heart rate monitors worn on the wrist by patients with stroke. The wrist worn heart rate monitor could improve the quality of rehabilitation by monitoring exercise intensity during physical therapy. [Participants and Methods] Thirty inpatients with subacute hemiparetic stroke wore heart rate monitors on both (non-paretic and paretic) wrists, as well as a chest heart rate monitor. We recorded the heart rate values measured at the wrist and chest every minute during physical therapy sessions. The wrist monitors were an optical heart rate measurement device based on photoplethysmography, and the chest monitor was a traditional chest device based on electrocardiography. The relative and absolute reliabilities between the heart rate measurements from the wrist and chest monitors were calculated. [Results] The intraclass correlation coefficients for model 2.1 ranged from 0.75 to 0.79. Bland-Altman analysis revealed a very slight fixed bias; however, no significant proportional bias was observed. For the non-paretic and paretic sides, the lower and upper limits of agreement ranged from −21.8 to 23.8 beats/min and from −20.8 to 21.6 beats/min, and the mean absolute percentage errors were 6.7% and 5.9%, respectively. The Cohen’s d value was small. [Conclusion] The relative reliability of the wrist heart rate monitors was substantial. The absolute reliability as bias in wrist heart rate and chest heart rate was small, but heart rates estimated from wrist monitors were not particularly accurate.

Lead (Pb) exposure assessment in dried blood spots using Total Reflection X-Ray Fluorescence (TXRF)

Lead (Pb) exposure is often determined through the analysis of whole blood though venipuncture poses ethical, economic, and logistical barriers. Dried Blood Spots (DBS) may help overcome such barriers though past studies measuring Pb in DBS have been challenged with quality control, small sample volumes, and other issues. Total Reflection X-Ray Fluorescence (TXRF) may help address some of these challenges but has yet to be used to measure Pb in DBS. As such, the aim of the current study was to develop, validate, and apply a method to analyze Pb in DBS samples using TXRF for use in human biomonitoring studies. First, we developed a novel method (tested a range of parameters), and then used blood reference materials to validate the method against performance criteria listed in ICH Q2A and Q2B and the European Bioanalysis Forum. Finally, we applied the method to two populations who exemplify divergent conditions (41 university members with relatively low Pb exposures sampled in a clinical environment; 40 electronic waste workers with relatively high Pb exposures sampled in a contaminated field setting). The limits of detection and quantification of the method were 0.28 and 0.69 μg/dL, respectively. The overall precision and accuracy of the method were 15% and 111%, respectively. The mean (±SD) DBS Pb levels by TXRF in the university members and e-waste workers were 0.78 (±0.46) and 3.78 (±3.01) μg/dL, respectively, and these were not different from Pb measures in venous whole blood using ICP-MS. Bland-Altman plot analyses indicated good agreement between DBS Pb measures by TXRF versus whole blood Pb measures by ICP-MS in both groups. By combining data from the two population groups, there was no significant constant bias (intercept of 0.02 μg/dL) or proportional bias (slope was −0.02) between the two measures, and the lower and upper LoA were −0.86 and 0.91 μg/dL, respectively, with a LoA range of 1.77 μg/dL. These results demonstrate that TXRF-based analysis of Pb content in DBS is a good alternative to the gold standard (i.e., ICP-MS analysis of whole blood), and helps overcome some of the challenges associated with current methods.

Agreement Between Standard Optical Coherence Tomography and Optical Coherence Tomography-Based Angiography in Estimating Retinal Nerve Fiber Layer Thickness

Objectives: To investigate the agreement between optical coherence tomography (OCT) and OCT-based angiography (OCT-A) in estimating retinal nerve fiber layer thickness (RNFLT) and evaluate the associations between peripapillary vessel density (VD) and RNFLT measurements obtained with both devices.Materials and Methods:The AngioVue (Optovue Inc., Fremont, CA, USA) and Spectralis (Heidelberg Engineering, Heidelberg, Germany) images of 325 patients were screened retrospectively. RNFLT values were recorded using both devices. The intraclass correlation coefficient (ICC) and Bland-Altman plots were obtained to investigate the agreement between the devices. Age- and intraocular pressure-corrected associations between VD and RNFLT measured by the two devices were analyzed using linear regression models.Results:ICC revealed excellent agreement for global, superior, inferior, and temporal RNFLT and good agreement for the nasal quadrant (ICC=0.895, 0.936, 0.923, 0.887, and 0.614, respectively). The Bland-Altman plots showed poor agreement for all measurements with a large span of limits of agreement and significant proportional bias (p<0.05). VD was found to be strongly associated with the RNFLT measurements of both devices (p<0.001).Conclusion:The disagreement between the devices should be considered in clinical practice, and the data should not be used interchangeably. The association of the peripapillary VD with RNFLT using both devices indicated that RNFLT assessed by the AngioVue could be used in glaucoma management along with VD.

Hand-held dynamometer to measure pressure pain thresholds: A double-blinded reliability and validity study

BackgroundPain is the most common complaint reported in the musculoskeletal setting. Quantitative sensory testing (QST) assists with pain mechanism identification, although QST is typically performed in research settings. It is possible that clinical utilization of QST may improve if clinically accessible tools can be reliably and validly used. ObjectiveTo determine if a hand-held dynamometer (HHD) can be a valid and reliable assessment of pressure pain threshold (PPT). DesignDouble-blinded validation study. MethodsEighteen healthy subjects (25.6 ± 3.4 years old) participated in this study. Two testers independently assessed PPT using a HHD and a digital algometer. Assessments followed previously described pressure algometry protocols. Testers and subjects were each blinded to data during assessments. ResultsIntra- and inter-rater reliability were excellent for the foot and face for both devices (ICC's > 0.9). Bland-Altman plots and intraclass correlation coefficients revealed good-excellent agreement with minimal proportional bias when normalizing device force at pain threshold to the circumference of the device applicator (ICC 95%CI: 0.56–0.95). Only poor-good agreement (ICC 95% CI: 0.30–0.76) and significant proportional bias was observed when normalizing to area (pressure). ConclusionsBased on the results of this study, when force is normalized by circumference of the applicator, a HHD was found to be a valid and reliable tool for measuring PPT. Clinicians may use HHD to detect relevant pain mechanisms at fault in their evaluation and treatment of pain. Additional research in various pathologic populations is warranted.

Comparison of canine urine specific gravity measurements between various refractometers in a clinical setting.

Veterinary facilities might use multiple refractometers and individuals to measure urine specific gravity (USG). Previous comparison studies show conflicting results. Furthermore, the clinical significance of measurement differences and interobserver variabilities has not been assessed. We aimed to determine statistically and clinically significant differences between four refractometers in measuring canine USG and subsequent categorization of urine concentrations and azotemia and determine the variability between different observers performing USG measurements. Fifty-nine specimens were included for the USG measurements with four refractometers by different observers. Each refractometer pair was compared using Spearman's rank correlation, Bland-Altman difference plots, and Deming regression analyses. Calculated bias was compared to set performance goals. Interobserver agreement was evaluated, and intraclass correlation coefficients were used to determine differences in the categorization of urine concentrations and azotemia (prerenal or renal). There was excellent correlation (rs =.99-1.00) between refractometers. All comparisons involving R4 showed significant constant and proportional biases. Mean bias met the clinical performance goals for all refractometers, except for comparisons with R4, where up to 17 results were outside the allowable bias. There was almost perfect agreement (rs =.999) between observers and excellent agreement (ICC=.96-.99) for the classification of urine concentrations. In azotemic patients (22%), there was perfect agreement (ICC=1.00) for the categorization of azotemia. In most cases, three of the refractometers evaluated in this study can be used interchangeably at all USG values, without affecting clinical decision-making. Multiple observers did not significantly affect decision-making.