Evaluation of Aution Max AX-4030 and 9UB Uriflet, 10PA Aution Sticks urine dipsticks in the automated urine test strip analysis

Urine dipstick for screening plasma glucose and bilirubin in low resource settings: a proof-of-concept study

Objectives

The purpose of this proof-of-concept study was to investigate whether a commercially available urine dipstick may provide potentially useful information for screening plasma glucose and bilirubin in human plasma samples.

Methods

Glucose and bilirubin were assayed in 60 anonymized lithium-heparin residual plasma samples using the Roche COBAS 8000 or after pipetting 10 µL of plasma onto the pads of a commercial urine dipstick. Semiquantitative urine test results obtained with the dipstick were directly compared to paired test results obtained with COBAS.

Results

Median plasma glucose values between COBAS and dipstick were slightly different (5.8 vs. 5.6 mmol/L; p=0.040), while no significant difference was found in bilirubin values between COBAS and dipstick (11.2 vs. 8.6 μmol/L; p=0.090). The Spearman's correlation between COBAS and dipstick was 0.83 (95% CI, 0.73-0.90; p<0.001) for plasma glucose and 0.78 (95% CI, 0.66-0.87; p<0.001) for plasma bilirubin, respectively. Cumulative agreement between COBAS and dipstick was high for both glucose (88%; kappa statistic statistics, 0.75; 95% CI, 0.58-0.92; p<0.001) and bilirubin (88%; kappa statistics, 0.76; 95% CI, 0.60-0.92; p<0.001).

Conclusions

The results of this proof-of-concept study indicate that the commercial urine test strip used in our study provides acceptable performance for screening plasma glucose and bilirubin levels compared with reference laboratory assays.

Uso de una tira reactiva paraorina en la evaluación de las concentraciones de glucosa y bilirrubina en plasma en entornos con recursos limitados: un estudio de prueba de concepto

Objetivos

El objetivo del presente estudio de prueba de concepto, era investigar si una tira reactiva comercial para orina aporta información potencialmente útil para la evaluación de glucosa y bilirrubina en muestras de plasma humano.

Métodos

Se determinaron las concentraciones de glucosa y bilirrubina en 60 muestras anonimizadas de plasma residual de heparina de litio, en un analizador Roche COBAS 8000 y en la tira reactiva comercial para orina, tras pipetear 10 µL de plasma, en las almohadillas que ésta incorpora. Se llevó a cabo una comparación directa entre los resultados semicuantitativos de la tira reactiva y los de las muestras pareadas obtenidos con el analizador COBAS.

Resultados

Se observaron leves diferencias entre el analizador COBAS y la tira reactiva en relación a la mediana de la concentración de glucosa (5,8 frente a 5,6 mmol/L, respectivamente; p=0,040). Por otro lado, no se observaron diferencias estadísticamente significativas en los valores de bilirrubina entre COBAS y la tira reactiva (11,2 frente a 8,6 μmol/L; p=0,090). El coeficiente de correlación de Spearman entre COBAS y la tira reactiva fue de 0,83 (IC 95 %, 0,73–0,90; p<0,001) para la glucosa en plasma, y 0,78 (IC 95 %, 0,66–0,87; p<0,001) para la bilirrubina en plasma. La concordancia acumulada entre COBAS y la tira reactiva fue alta tanto para la glucosa (88 %; coeficiente kappa, 0.75; IC 95 %, 0,58–0,92; p<0,001) como para la bilirrubina (88 %; coeficiente kappa, 0,76; IC 95 %, 0,60–0.92; p<0,001).

Conclusiones

Los resultados del estudio de prueba de concepto indican que la tira reactiva comercial para orina de nuestro estudio posee un rendimiento aceptable en la determinación de las concentraciones de glucosa y bilirrubina en plasma, en comparación con las pruebas analíticas de referencia.

Internal Quality Control Data of Urine Reagent Strip Tests and Derivation of Control Rules Based on Sigma Metrics

Background

Urine reagent strip test (URST) results are semi-quantitative; therefore, the precision of URSTs is evaluated as the proportion of categorical results from repeated measurements of a sample that are concordant with an expected result. However, URSTs have quantitative readout values before ordinal results challenging statistical monitoring for internal quality control (IQC) with control rules. This study aimed to determine the sigma metric of URSTs and derive appropriate control rules for IQC.

Methods

The URiSCAN Super Plus fully automated urine analyzer (YD Diagnostics, Yongin, Korea) was used for URSTs. Change in reflectance rate (change %R) data from IQC for URSTs performed between November 2018 and May 2020 were analyzed. Red blood cells, bilirubin, urobilinogen, ketones, protein, glucose, leukocytes, and pH were measured from 2-3 levels of control materials. The total allowable error (TE_a) for a grade was the difference in midpoints of a predefined change %R range between two adjacent grades. The sigma metric was calculated as TE_a/SD. Sigma metric-based control rules were determined with Westgard EZ Rules 3 software (Westgard QC, Madison, WI, USA).

Results

Seven out of the eight analytes had a sigma metric >4 in the control materials with a negative grade (-), which were closer to the cut-offs. Corresponding control rules ranged from 1_2.5s to 1_3.5s.

Conclusions

Although the URST is a semi-quantitative test, statistical IQC can be performed using the readout values. According to the sigma metric, control rules recommended for URST IQC in routine clinical practice are 1_2.5s to 1_3.5s.

Prospective, observational study comparing automated and visual point-of-care urinalysis in general practice

OBJECTIVE

Point-of-care testing (POCT) urinalysis might reduce errors in (subjective) reading, registration and communication of test results, and might also improve diagnostic outcome and optimise patient management. Evidence is lacking. In the present study, we have studied the analytical performance of automated urinalysis and visual urinalysis compared with a reference standard in routine general practice.

SETTING

The study was performed in six general practitioner (GP) group practices in the Netherlands. Automated urinalysis was compared with visual urinalysis in these practices. Reference testing was performed in a primary care laboratory (Saltro, Utrecht, The Netherlands).

PRIMARY AND SECONDARY OUTCOME MEASURES

Analytical performance of automated and visual urinalysis compared with the reference laboratory method was the primary outcome measure, analysed by calculating sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) and Cohen's κ coefficient for agreement. Secondary outcome measure was the user-friendliness of the POCT analyser.

RESULTS

Automated urinalysis by experienced and routinely trained practice assistants in general practice performs as good as visual urinalysis for nitrite, leucocytes and erythrocytes. Agreement for nitrite is high for automated and visual urinalysis. κ's are 0.824 and 0.803 (ranked as very good and good, respectively). Agreement with the central laboratory reference standard for automated and visual urinalysis for leucocytes is rather poor (0.256 for POCT and 0.197 for visual, respectively, ranked as fair and poor). κ's for erythrocytes are higher: 0.517 (automated) and 0.416 (visual), both ranked as moderate. The Urisys 1100 analyser was easy to use and considered to be not prone to flaws.

CONCLUSIONS

Automated urinalysis performed as good as traditional visual urinalysis on reading of nitrite, leucocytes and erythrocytes in routine general practice. Implementation of automated urinalysis in general practice is justified as automation is expected to reduce human errors in patient identification and transcribing of results.

Analytical performance, agreement and user-friendliness of six point-of-care testing urine analysers for urinary tract infection in general practice

OBJECTIVE

Various point-of-care testing (POCT) urine analysers are commercially available for routine urine analysis in general practice. The present study compares analytical performance, agreement and user-friendliness of six different POCT urine analysers for diagnosing urinary tract infection in general practice.

SETTING

All testing procedures were performed at a diagnostic centre for primary care in the Netherlands. Urine samples were collected at four general practices.

PRIMARY AND SECONDARY OUTCOME MEASURES

Analytical performance and agreement of the POCT analysers regarding nitrite, leucocytes and erythrocytes, with the laboratory reference standard, was the primary outcome measure, and analysed by calculating sensitivity, specificity, positive and negative predictive value, and Cohen's κ coefficient for agreement. Secondary outcome measures were the user-friendliness of the POCT analysers, in addition to other characteristics of the analysers.

RESULTS

The following six POCT analysers were evaluated: Uryxxon Relax (Macherey Nagel), Urisys 1100 (Roche), Clinitek Status (Siemens), Aution 11 (Menarini), Aution Micro (Menarini) and Urilyzer (Analyticon). Analytical performance was good for all analysers. Compared with laboratory reference standards, overall agreement was good, but differed per parameter and per analyser. Concerning the nitrite test, the most important test for clinical practice, all but one showed perfect agreement with the laboratory standard. For leucocytes and erythrocytes specificity was high, but sensitivity was considerably lower. Agreement for leucocytes varied between good to very good, and for the erythrocyte test between fair and good. First-time users indicated that the analysers were easy to use. They expected higher productivity and accuracy when using these analysers in daily practice.

CONCLUSIONS

The overall performance and user-friendliness of all six commercially available POCT urine analysers was sufficient to justify routine use in suspected urinary tract infections in general practice.