Use of voltammetric analysis for fast and objective discrimination of the etiology, evolution, and bacterial infection of lower limb ulcers

CONSTRUCT VALIDITY AND RELIABILITY OF THE LEG ULCER MEASUREMENT TOOL SCALE ADAPTED FOR BRAZIL

ABSTRACT Objective: to validate the Portuguese version of the Leg Ulcer Measurement Tool regarding construct and reliability. Method: this is a methodological research study. Data collection was conducted between January and July 2019. A total of 105 participants were included for construct validation and internal consistency and, of these, 50 were selected for intra-observer stability. For the analysis of construct validity, factor analysis was performed; for internal consistency, Cronbach's alpha coefficient was calculated, and for stability, the intraclass correlation coefficient. Results: A total of 12items were confirmed for the Brazilian reality, meeting all the theoretical requirements of the factor analysis model. As for the internal consistency (reliability) analysis, the Cronbach's alpha coefficient values (α=0.711) showed that the set of items that make up the scale measures the same characteristics and presents internal consistency. In the global stability analysis (ICC=0.823), the Leg Ulcer Measurement Tool test and retest scores presented good agreement, showing that the adapted scale is stable. Conclusion: the Leg Ulcer Measurement Tool scale adapted to the Portuguese language contains 12 items, with scores varying from 0 to 4 and, thus, produces a score from 0 to 48 points. It presents construct validity analyzed by means of factor analysis and reliability in terms of internal consistency and stability.

Design of an Innovative Methodology for Cerebrospinal Fluid Analysis: Preliminary Results

Cerebrospinal fluid (CSF) analysis supports diagnosis of neurodegenerative diseases (NDs), however a number of issues limits its potentialities in clinical practice. Here, a newly developed technique for fluid voltammetry, relying on a simple sensor (BIOsensor-based multisensorial system for mimicking Nose, Tongue and Eyes, BIONOTE), was used to test the applicability for CSF analysis. BIONOTE was initially calibrated on an artificial CSF-like solution and then applied on human CSF, either immediately after collection or after refrigerated storage. Following optimization, it was used to evaluate 11 CSF samples correlating the electrochemical dataset with CSF routine parameters and biomarkers of neurodegeneration. Multivariate data analysis was performed for model elaboration and calibration using principal component analysis and partial least squares discriminant analysis. BIONOTE presented a high capacity to predict both physiological and pathological constituents of artificial CSF. It differentiated distinct fresh human CSF samples well but lost accuracy after refrigerated storage. The electrochemical analysis-derived data correlated with either CSF routine cytochemical indexes or a biomarker of neurodegeneration. BIONOTE resulted as being a reliable system for electrochemical analysis of CSF. The CSF fingerprint provided by the sensor has shown itself to be sensitive to CSF modification, thus it is potentially representative of CSF alteration. This result opens the way to its testing in further study addressed at assessing the clinical relevance of the methodology. Because of its advantages due to the ease and rapidity of the methodology, a validation study is now required to translate the technique into clinical practice and improve diagnostic workup of NDs.

Voltammetric analysis for distinguishing portal hypertension-related from malignancy-related ascites: A proof of concept study

Background

Serum-ascites albumin gradient (SAAG) remains the most sensitive and specific marker for the differentiation of ascites due to portal hypertension from ascites due to other causes. SAAG has some limitations and may fail in selected conditions. Voltammetric analysis (VA) has been used for the detection of electroactive species of biological significance and has proven effective for detection infections in biological fluids.

Aims

In this study, we compared the accuracy of voltammetric analysis (VA) with that of SAAG to differentiate ascites due to portal hypertension from that having a different origin.

Methods

80 ascites samples were obtained from patients undergoing paracentesis at the Campus Bio-Medico Hospital of Rome. VA was performed using the BIONOTE device. The ability of VA to discriminate ascitic fluid etiology and biochemical parameters was evaluated using Partial Least Square Discriminant Analysis (PLS-DA), with ten-fold cross-validations.

Results

Mean age was 68.6 years (SD 12.5), 58% were male. Ascites was secondary to only portal hypertension in 72.5% of cases (58 subjects) and it was secondary to a baseline neoplastic disease in 27.5% of cases (22 subjects). Compared to SAAG≥1.1, e-tongue predicted ascites from portal hypertension with a better accuracy (92.5% Vs 87.5%); sensitivity (98.3% Vs 94.8%); specificity (77.3% Vs 68.2%); predictive values (PPV 91.9% Vs 88.7% and NPV 94.4% Vs 83.3%). VA correctly classified ascites etiology in 57/58 (98.2%) of cases with portal hypertension and in 17/22 (77.2%) of cases with malignancy. Instead, VA showed poor predictive capacities towards total white blood count and polymorphonuclear cell count.

Conclusions

According to this proof of concept study, VA qualifies as a promising low-cost and easy method to discriminate between ascites secondary to portal hypertension and ascites due to malignancy.