Improving hemoglobin estimation accuracy through standardizing of light-emitting diode power

Nowadays, hemoglobin monitoring is essential during surgeries, blood donations, and dialysis. Which are normally done using invasive methods. To monitor hemoglobin, a non-invasive hemoglobin meter was developed with five fixed light-emitting diode (LED) wavelengths at 670 nm, 770 nm, 810 nm, 850 nm, 950 nm and controlled using an Arduino Uno embedded development board. A photodetector with an on-chip trans-impedance amplifier was utilized to acquire the transmitted signal through the finger using the photoplethysmography (PPG) principle. Before the standardization of LED power, we had tested the designed system on fifteen subjects for the five wavelengths and estimated the hemoglobin with an accuracy of 96.51% and root mean square error (RMSE) of 0.57 gm/dL. To further improve the accuracy, the LED power was standardized and the PPG signal was reacquired on the same subjects. With this, the accuracy improved to 98.29% and also reduced the RMSE to 0.36 gm/dL. The designed system with LED power standardization showed a good agreement with pathology results with the coefficient of determination R²=0.981. Also, Bland–Altman analysis was used to evaluate the designed system and it showed good agreement between the two measurements.

Twenty-four hours intraocular pressure in keratoconic eyes assessed by applanation tonometry and Tono-Pen AVIA

AIM: To assess intraocular pressure (IOP) during the daily curve of intraocular pressure (DCPo) in keratoconic eyes and compare Goldmann applanation tonometer (GAT), without and with astigmatism correction (nGAT and cGAT) and Tono-Pen AVIA (TPA) assessment methods. METHODS: Thirty-nine keratoconic eyes of 24 patients were assessed. DCPo was evaluated with five IOP measurements; four were performed with a GAT (nGAT and cGAT), and a Tono-Pen AVIA (TPA) at various times throughout the day. RESULTS: Mean IOP DCPo values (mm Hg) were: nGAT, 9.9±2.6; cGAT, 11.3±2.6; TPA 12.3±3.1. Mean IOP DCPo differences (mm Hg) and Spearman's correlation coefficients were as follows: cGATc-nGAT, 1.32±1.31, rs=0.879 (P<0.01); cGAT-TPA, -1.02±2.08, rs=0.723 (P<0.01); and nGAT-TPA, -2.35±2.23, rs=0.730 (P<0.01). Bland-Altman analysis for agreement between cGAT-TPA and nGAT-TPA mean IOP DCPo measurements revealed a mean difference of 1.02 (95%CI, 0.35-1.70) and 2.35 (95%CI, 1.62-3.07) mm Hg, respectively. Regression analysis yielded the following equation: TPA IOP=5.49+0.775×cGAT-0.015×ACD-0.299×corneal astig matism, which allowed us to infer TPA IOP values from other parameters. CONCLUSION: In keratoconic eyes, IOP peaks of DCPo measurements are identified at 6 a.m., independent of the tonometer. The mean DCPo values are: TPA>cGAT>nGAT. IOP TPA measures are predictive of cGAT values, adjusted according to anterior chamber depth and corneal astigmatism.

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.

Validation of the estimated glomerular filtration rate equation for Japanese children younger than 2 years

Background We have developed a simple and easy method of estimating the glomerular filtration rate (eGFR) of serum creatinine in Japanese children (eGFRUemura). The eGFR equation is for children aged 2–18 years. Therefore Uemura et al. developed an equation for children younger than 2 years (eGFRunder 2). The aim of the present study was to validate this new equation. Methods We collected the data of 13 patients from previous studies and compared the results of eGFRunder 2, eGFRUemura, and updated eGFR developed by Schwartz (eGFRSchwartz) with measured GFR using mean error (ME), root mean square error (RMSE), P30 and Bland–Altman analysis. Results The ME of eGFRunder 2, eGFRUemura and eGFRSchwartz were 2.3 ± 15.9, 7.7 ± 14.5, and 16.0 ± 18.2 ml/min/1.73m2, respectively. The RMSEs were 15.5, 15.9, and 49.6, respectively. The P30 values were 76.9%, 76.9%, and 53.8%, respectively. The graph of Bland–Altman bias analysis showed fan-shape. The eGFRunder 2 equation was the most accurate in the three equations. Conclusion The eGFRunder 2 equation was useful for Japanese children younger than 2 years.

Evaluation of the Validity of Digital Optical Microscopy in the Assessment of Marginal Adaptation of Dental Adhesive Interfaces

Analysis of marginal adaptation of dental adhesive interfaces using scanning electron microscopy has proven to be a powerful nondestructive method to evaluate the quality of adhesion. This methodology is, however, time-consuming and needs expensive equipment. The purpose of this study was to evaluate the possibility and efficiency of using a digital optical microscope (DOM) to perform marginal analysis and to compare it with the scanning electron microscope (SEM) analysis. Fifteen defect-free molars were selected for this study. Class V cavities were prepared and restored with resin composite, and epoxy replicas were obtained from silicone impressions of the restored teeth. Custom-made image analysis software was then used to measure the percentage of the noncontinuous margins (NCM) of each sample. To compare the DOM to the gold standard, SEM, each sample was analyzed 10 times using the DOM and three times using the SEM, by the same experienced operator. The repeatability coefficient and concordance were evaluated, and a Bland and Altman analysis was used for comparison of the two methods of measurements. To validate the DOM analysis method, an ANOVA approach (Gage R R) was used. Repeatability and reproducibility, which are two components of precision to validate the DOM analysis system, were calculated. For this, the same restorations were analyzed by two additional operators three times with the DOM. The duration of each step of the analysis using both methods was also recorded as a secondary outcome. Regarding the repeatability of each method, the Friedman test showed no statistically significant difference within the repetitions of measurements by SEM and DOM (p = 0.523 and p = 0.123, respectively). Moreover, the Bland-Altman analysis revealed a bias of 0.86 and concluded no statistically significant difference between the two methods, DOM and SEM. ANOVA evaluated DOM measurement system variation including the variances of repeatability and reproducibility that represented, respectively, 0.3% and 4% of the variance components. Reproducibility or inter-operator variability represented the principal source of variability with a statistically significant difference (p = 0.024). The time required for analysis with SEM was almost double that of DOM. The use of digital optical microscopy appears to be a valid alternative to the SEM for the analysis of marginal adaptation of dental adhesive interfaces. Further studies to evaluate the effect of training of operators in digital optical microscopy could reveal higher accuracy for this method and inter-operator agreement when experience is gained.

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.

311 A new color Doppler-based echocardiographic technique for evaluation of intraventricular flow dynamics: first application to normal subjects, athletes, and patients

Aims A new echocardiographic, color Doppler-based technique, named HyperDoppler, has been recently introduced for non-invasive evaluation of intracardiac flow dynamics. The aim of this study was to verify the feasibility and reproducibility of this technique and its capability to differentiate geometrical and energy measures of vortex flow within the left ventricle (LV) in normal subjects, athletes and patients with heart failure. Methods and results Two Italian cardiology centres enrolled each one 100 unselected, consecutive patients presenting at the echocardiography laboratory for a clinical examination, regardless of the indication to echocardiography. In these patients, the feasibility, repeatability, reproducibility, and inter-centre reproducibility of the HyperDoppler technique were tested using the intraclass correlation coefficient (ICC) and Bland–Altman analysis. In addition, 50 normal subjects, 30 professional athletes, and 50 patients with stabilized chronic heart failure and LV ejection fraction &lt;40% were enrolled. Images were acquired using a MyLab X8 echo-scanner and analysed to provide the following vortex flow measures: vortex area, normalized with the LV area; vortex intensity (i.e. the integral of the vorticity inside the vortex), normalized with the total vorticity; vortex depth (the distance of its centre from the LV base) and length along the base-apex direction, both normalized with the LV length; and the total kinetic energy dissipation (KED). Feasibility of HyperDoppler was very high (94.5%). According to the ICC values, at Centre 1 repeatability and reproducibility of vortex flow measures in unselected patients were good for vortex area (0.82, 0.85), length (0.83, 0.82) and depth (0.87, 0.84) and excellent for vortex intensity (0.92, 0.90) and KED (0.98, 0.98). Results of the Bland–Altman analysis showed no bias nor consistent under/overestimations of flow measures, with 95% of points always lying within the limits of agreement for each flow measure. Centre 2 provided similar repeatability and reproducibility evaluations for all the vortex measures, thus supporting a good-to-excellent inter-centre reproducibility. Athletes had greater vortex area, intensity, and KED compared to healthy subjects while they had smaller vortex length and depth and greater KED compared to patients with heart failure and reduced LV ejection fraction. In comparison with healthy subjects, heart failure patients showed greater vortex area, length, depth, and intensity but smaller KED. Combining vortex flow measures, the LV flow profile of healthy individuals, athletes, and heart failure patients could be differentiated. Conclusions HyperDoppler is a new ultrasound technique which is feasible, reliable, and practical for assessment of LV flow dynamics. It can quantitate several measures of the LV vortex and may distinguish normal subjects and patients. Future studies are needed to clarify how to implement this technique in cardiology clinical practice.

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.

Concordance rate of a four-quadrant plot for repeated measurements

Background To assure the equivalence between new clinical measurement methods and the standard methods, the four-quadrant plot and the plot’s concordance rate is used in clinical practice, along with Bland-Altman analysis. The conventional concordance rate does not consider the correlation among the data on individual subjects, which may affect its proper evaluation. Methods We propose a new concordance rate for the four-quadrant plot based on multivariate normal distribution to take into account the covariance within each individual subject. The proposed concordance rate is formulated as the conditional probability of the agreement. It contains a parameter to set the minimum concordant number between two measurement methods, which is regarded as agreement. This parameter allows flexibility in the interpretation of the results. Results Through numerical simulations, the AUC value of the proposed method was 0.967, while that of the conventional concordance rate was 0.938. In the application to a real example, the AUC value of the proposed method was 0.999 and that of the conventional concordance rate was 0.964. Conclusion From the results of numerical simulations and a real example, the proposed concordance rate showed better accuracy and higher diagnosability than the conventional approaches.