Accuracy and precision of non-invasive continuous haemoglobin concentration monitoring in diabetic patients

Background Accuracy and precision of non-invasive continuous haemoglobin concentration (SpHb) provided by Masimo device in diabetic patients is poorly studied. This retrospective analysis aimed to provide data on SpHb accuracy and precision in diabetic patients. Results The sample size population consisted of 14 patients, with 56 SpHb/Lab data pairs. Lab value showed a mean ± standard deviation (SD) of 13.2 ± 1.2 g/dL, whilst SpHb showed a mean ± SD of 11.8 ± 1.1 g/dL. Linear regression analysis between Lab/SpHb data pairs showed a r of 0.8960 (CI95% 0.8281-0.9379, p value < 0.0001). SpHb underestimated the real Hb values provided by Lab. Bland-Altman analysis showed that SpHb accuracy was −1.37 g/dL (CI95% −1.51 to −1.22 g/dL, p value < 0.0001), precision of 0.55 g/dL, lower LOA −2.45 g/dL (CI95% −2.71 to −2.20 g/dL) and upper LOA −0.28 g/dL (CI95% −0.53 to −0.02 g/dL). Conclusions For the first time, we provided data on SpHb accuracy and precision in the diabetic population. SpHb showed a high correlation coefficient when compared with Lab values, but the wide LOA limits its accuracy.

A Food Frequency Questionnaire for Hemodialysis Patients in Bangladesh (BDHD-FFQ): Development and Validation

Diet is a recognized risk factor and cornerstone for chronic kidney disease (CKD) management; however, a tool to assess dietary intake among Bangladeshi dialysis patients is scarce. This study aims to validate a prototype Bangladeshi Hemodialysis Food Frequency Questionnaire (BDHD-FFQ) against 3-day dietary recall (3DDR) and corresponding serum biomarkers. Nutrients of interest were energy, macronutrients, potassium, phosphate, iron, sodium and calcium. The BDHD-FFQ, comprising 132 food items, was developed from 606 24-h recalls and had undergone face and content validation. Comprehensive facets of relative validity were ascertained using six statistical tests (correlation coefficient, percent difference, paired t-test, cross-quartiles classification, weighted kappa, and Bland-Altman analysis). Overall, the BDHD-FFQ showed acceptable to good correlations (p < 0.05) with 3DDR for the concerned nutrients in unadjusted and energy-adjusted models, but this correlation was diminished when adjusted for other covariates (age, gender, and BMI). Phosphate and potassium intake, estimated by the BDHD-FFQ, also correlated well with the corresponding serum biomarkers (p < 0.01) when compared to 3DDR (p > 0.05). Cross-quartile classification indicated that <10% of patients were incorrectly classified. Weighted kappa statistics showed agreement with all but iron. Bland-Altman analysis showed positive mean differences were observed for all nutrients when compared to 3DDR, whilst energy, carbohydrates, fat, iron, sodium, and potassium had percentage data points within the limit of agreement (mean ± 1.96 SD), above 95%. In summary, the BDHD-FFQ demonstrated an acceptable relative validity for most of the nutrients as four out of the six statistical tests fulfilled the cut-off standard in assessing dietary intake of CKD patients in Bangladesh.

Analytical comparison between two automated biochemical analyzer systems: Roche Cobas 8000 and Mindray BS2000M

Summary Background. The values of biomarkers play a central role in routine clinical decision-making. Whereas, the performances of different automated chemical analyzers remain unclear. To determine the performances of different platforms, we evaluated the capability between Roche Cobas 8000 and Mindray BS2000M. Methods. A total of 1869 remaining serum samples were collected. CK, LDH-1, RBP, Cys-c, IgA, IgM and IgG were assessed by using paired-t test, Passing-Bablok regression analysis and Bland Altman analysis according to CLSI EP5-A3. Results. There were significant in average bias of all items between two machines (P < 0.001). Due to the 95% confidence interval of intercept A included 0, CK, LDH-1, Cys-c and IgG were not show systemic error in Passing-Bablok regression analysis. Except for IgA, the r values and correlation coefficient of all items were higher than 0.91, which showed that the correlation and consistency is good. The Bland-Altman analysis showed that two instruments had more than 95% of the points apart from CK, LDH-1, and IgA. Conclusions. It can be considered that the two instruments have good correlation and consistency in CK, LDH-1, RBP, Cys-c, IgM and IgG, and the two instruments are interchangeable and can replace each other.

Validation of the predictive accuracy of health-state utility values based on the Lloyd model for metastatic or recurrent breast cancer in Japan

IntroductionAlthough there is a lack of data on health-state utility values (HSUVs) for calculating quality-adjusted life-years in Japan, cost–utility analysis has been introduced by the Japanese government to inform decision making in the medical field since 2016.ObjectivesThis study aimed to determine whether the Lloyd model which was a predictive model of HSUVs for metastatic breast cancer (MBC) patients in the UK can accurately predict actual HSUVs for Japanese patients with MBC.DesignThe prospective observational study followed by the validation study of the clinical predictive model.Setting and participantsForty-four Japanese patients with MBC were studied at 336 survey points.MethodsThis study consisted of two phases. In the first phase, we constructed a database of clinical data prospectively and HSUVs for Japanese patients with MBC to evaluate the predictive accuracy of HSUVs calculated using the Lloyd model. In the second phase, Bland-Altman analysis was used to determine how accurately predicted HSUVs (based on the Lloyd model) correlated with actual HSUVs obtained using the EuroQol 5-Dimension 5-Level questionnaire, a preference-based measure of HSUVs in patients with MBC.ResultsIn the Bland-Altman analysis, the mean difference between HSUVs estimated by the Lloyd model and actual HSUVs, or systematic error, was −0.106. The precision was 0.165. The 95% limits of agreement ranged from −0.436 to 0.225. The t value was 4.6972, which was greater than the t value with 2 degrees of freedom at the 5% significance level (p=0.425).ConclusionsThere were acceptable degrees of fixed and proportional errors associated with the prediction of HSUVs based on the Lloyd model for Japanese patients with MBC. We recommend that sensitivity analysis be performed when conducting cost-effectiveness analyses with HSUVs calculated using the Lloyd model.

Vascular Access Flow during Dialysis: Does Needle Orientation Matter?

Background: Monitoring of vascular access outflow (VAO) in dialysis is based on the indicator dilution method by ultrasound (UD). The role of arterial needle orientation in VAO measurement is not clear. We compared the impact of the retrograde (RET) versus the antegrade orientation (ANT) in terms of (a) VAO (UD) and (b) dialysis adequacy. Moreover, we compared VAO (UD ANT and RET orientation) with VAO measured by Doppler ultrasound. Methods: 22 patients participated in the study. Inclusion criteria: Dialysis > 6 months with a functioning AVF, no stenosis, no active infection, EF > 45% and informed consent. 4 flow measurements were taken on the same dialysis day (4 consecutive weeks). To account for blood pressure variation, we “corrected” VAO for a mean arterial pressure of 100 mmHg. Doppler VAO was measured just before dialysis. Means were compared by the paired t-test. For correlation and agreement, linear regression and Bland-Altman analysis were performed respectively. Results: Mean VAO (UD) was higher in the (ANT) versus the (RET) orientation: 1286.17 mL/min (SD = 455.78, 95%CI = 1084–1488) versus 1189.96 mL/min (SD = 401.05, 95%CI = 1012–1368) (p = 0.013) with a mean difference of 96.21 mL/min (5.66%). Mean Kt/V (RET orientation) was 1.57 (SD = 0.10, 95%CI = 1.52–1.61) versus 1,55 (SD = 0.10, 95%CI = 1.50–1.60) (ANT) orientation (p = 0.062). Recirculation was always 0%. The mean VAO (Doppler) was 1079.54 mL/min (SD = 356.04, 95%CI = 922–1237), 16% lower than VAO measured by UD with (ANT) orientation (p = 0.009) and 9.3% lower than the VAO in the (RET) orientation (p = 0.113). Linear regression analysis showed that VA flows (ANT versus RET) orientation of the needle correlates well between them (r = 0.93, p < 0.001) but show poor agreement (Bland–Altman analysis). Conclusion: VAO (UD) in the RET orientation was significantly lower than VAO in the ANT orientation and more consistent with VAO assessed by Doppler without influencing dialysis adequacy. Therefore, when using UD for VAO surveillance, the RET orientation should be used.

The response of the accommodation system to digital and print images

Background: The transition from traditional print medium to a digital medium may affect the accommodative response (AR) because of the differences in the characteristics of the targets viewed.Aim: This study investigated how the accommodation system responded to targets displayed on a tablet computer compared to that on paper.Setting: The study was conducted amongst students at a university in South Africa.Methods: Using a quantitative, cross-sectional study the AR, amplitude of accommodation (AA), and accommodative facility (AF) were assessed with a target on an iPad and a paper-based one on a non-probability sample of 30 university students. Data was analysed using descriptive statistics and Bland Altman plots.Results: The median AR with a tablet was +0.25 dioptre (D) compared to +0.21 D with the paper-based target. This difference was neither statistically nor clinically significant. The median AA with a tablet computer target was 10.59 D and 9.85 D with a paper-based target. While this difference was statistically significant (p = 0.002), Bland Altman analysis revealed comparable measurements with both types of targets. Both Wilcoxon Signed Ranks Test (p = 0.462) and Bland Altman analysis found comparable medians for AF obtained with a target on paper (7.67 cycles per minute [cpm]) and a target on the tablet computer (7.17 cpm) to be comparable.Conclusion: The accuracy, strength and flexibility of accommodation were comparable for tablet computer and paper-based targets.

Comparison of enzyme-linked fluorescent assay and electrochemiluminescence immune assay in procalcitonin measurement

Background Procalcitonin (PCT) measurement is required for intensive care patients with systemic inflammation symptoms, early diagnosis of possible infections, and evaluation of sepsis severity and prognosis. Objectives We aimed to determine the analytical performance of PCT measurement in a Roche Modular E170 (ECLIA) analyzer and compare the performance with VIDAS (BRAHMS/ELFA) analyzer findings. Material and methods Within-day and between-day precision value, linearity was determined, and two methods were compared with regression and Bland–Altman analysis. Results Both ECLIA and ELFA assays indicated excellent precision, where within-day precision varied between 1.18% and 3.97% CV, and between-day precision varied between 1.77% and 3.93% CV. The ECLIA method was linear up to 62.15 ng/mL. The arithmetic mean was 6.02 ng/mL with the ECLIA method and 8.02 ng/mL with the ELFA method. The correlation coefficient was r=0.996 and p=0.001. The correlation was linear between the two methods. Regression equation was found y=0.78x − 0.23. The Bland–Altman figure was revealed the difference between the methods was specifically in lower concentrations (<0.15 ng/mL). Conclusions Both methods show good precision and correlation. It was determined that the difference between methods was significant, especially at <0.15 ng/mL concentration.

Assessment of Operator Reliability in Ultrasound of the Median and Ulnar Nerve Using Bland-Altman Analysis

Currently, there is no standardized method to evaluate operator reliability in nerve ultrasound. A short prospective protocol using Bland–Altman analysis was developed to assess the level of agreement between operators with different expertise levels. A control rater without experience in nerve ultrasound, three novices after two months of training, an experienced rater with two years of experience, and a reference rater performed blinded ultrasound examinations of the left median and ulnar nerve in 42 nerve sites in healthy volunteers. The precision of Bland–Altman agreement analysis was tested using the Preiss–Fisher procedure. Intraclass correlation coefficients (ICC), coefficients of variation, and Bland–Altman limits of agreement were calculated. The sample size calculation and Preiss–Fisher procedure showed a sufficient precision of Bland–Altman agreement analysis. Limits of agreement of all trained novices ranged from 2.0 to 2.9 mm2 and were within the test’s maximum tolerated difference. Ninety-five percent confidence intervals of limits of agreement revealed a higher precision in the experienced rater’s measurements. Operator reliability in nerve ultrasound of the median and ulnar nerve arm nerves can be evaluated with a short prospective controlled protocol using Bland–Altman statistics, allowing a clear distinction between an untrained rater, trained novices after two months of training, and an experienced rater.

3D volume reconstruction of brain tissues using nonlinear filters, k-means clustering, and Bland-Altman analysis

This paper aims to provide a sound estimation of the true value and proportion of white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) of the brain DTI images for a proper 3D volume reconstruction. During the pre-processing stage, two nonlinear filters are operated, i.e. bilateral and anisotropic diffusion. The segmentation of each brain tissue is performed using the k-means clustering algorithm. To minimize filters bias and for obtaining the best reproducible results, a statistical analysis has been performed. Thus, the skewness and kurtosis statistics features were computed for each segmented brain tissue and filter. The fuzzy k-means method allows for clustering analysis and the Bland-Altman analysis investigates the agreement between two filtering techniques of the same statistics feature and brain tissue. Then the 3D reconstruction method is presented using ImageJ and the image stacks for raw and processed data. We conclude that anisotropic diffusion filter offers the best results and 3D reconstruction of brain tissues is feasible.

The ensemble learning model is not better than the Asian modified CKD-EPI equation for glomerular filtration rate estimation in Chinese CKD patients in the external validation study

Objective To assess the clinical practicability of the ensemble learning model established by Liu et al. in estimating glomerular filtration rate (GFR) and validate whether it is a better model than the Asian modified Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in a cohort of Chinese chronic kidney disease (CKD) patients in an external validation study. Methods According to the ensemble learning model and the Asian modified CKD-EPI equation, we calculated estimated GFRensemble and GFRCKD-EPI, separately. Diagnostic performance of the two models was assessed and compared by correlation coefficient, regression equation, Bland–Altman analysis, bias, precision and P30 under the premise of 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA) dual plasma sample clearance method as reference method for GFR measurement (mGFR). Results A total of 158 Chinese CKD patients were included in our external validation study. The GFRensemble was highly related with mGFR, with the correlation coefficient of 0.94. However, regression equation of GFRensemble = 0.66*mGFR + 23.05, the regression coefficient was far away from one, and the intercept was wide. Compared with the Asian modified CKD-EPI equation, the diagnostic performance of the ensemble learning model also demonstrated a wider 95% limit of agreement in Bland-Altman analysis (52.6 vs 42.4 ml/min/1.73 m2), a poorer bias (8.0 vs 1.0 ml/min/1.73 m2, P = 0.02), an inferior precision (18.4 vs 12.7 ml/min/1.73 m2, P < 0.001) and a lower P30 (58.9% vs 74.1%, P < 0.001). Conclusions Our study showed that the ensemble learning model cannot replace the Asian modified CKD-EPI equation for the first choice for GFR estimation in overall Chinese CKD patients.