Analytical Performance, Agreement and User-Friendliness of Six Point-Of-Care Testing Urine Analysers for Urinary Tract Infection in General Practice
Total Page:16
File Type:pdf, Size:1020Kb
Open Access Research BMJ Open: first published as 10.1136/bmjopen-2014-006857 on 18 May 2015. Downloaded from Analytical performance, agreement and user-friendliness of six point-of-care testing urine analysers for urinary tract infection in general practice Marjolein J C Schot,1 Sanne van Delft,2 Antoinette M J Kooijman-Buiting,2 Niek J de Wit,1 Rogier M Hopstaken2 To cite: Schot MJC, van ABSTRACT Strengths and limitations of this study Delft S, Kooijman- Objective: Various point-of-care testing (POCT) urine Buiting AMJ, et al. Analytical analysers are commercially available for routine urine ▪ performance, agreement and This is the first time that different commercially analysis in general practice. The present study user-friendliness of six point- available point of care testing (POCT) urine ana- of-care testing urine compares analytical performance, agreement and lysers have been evaluated on analytical perform- analysers for urinary tract user-friendliness of six different POCT urine analysers ance, agreement and user-friendliness. infection in general practice. for diagnosing urinary tract infection in general ▪ All six POCT urine analysers in our study have BMJ Open 2015;5:e006857. practice. good analytical performance. doi:10.1136/bmjopen-2014- Setting: All testing procedures were performed at ▪ First-time users indicate that the analysers are 006857 a diagnostic centre for primary care in the easy to use. They expect higher productivity and Netherlands. Urine samples were collected at four accuracy when using these analysers in daily ▸ Prepublication history and general practices. practice. additional material is Primary and secondary outcome measures: ▪ This study does not address whether the use of available. To view please visit Analytical performance and agreement of the POCT POCT urine analysers in the primary care setting the journal (http://dx.doi.org/ analysers regarding nitrite, leucocytes and has added value compared with visual reading. 10.1136/bmjopen-2014- erythrocytes, with the laboratory reference standard, A study on this subject is currently being 006857). was the primary outcome measure, and analysed by conducted. http://bmjopen.bmj.com/ Received 8 October 2014 calculating sensitivity, specificity, positive and negative Revised 4 February 2015 predictive value, and Cohen’s κ coefficient for Accepted 17 March 2015 agreement. Secondary outcome measures were the INTRODUCTION user-friendliness of the POCT analysers, in addition to With urinary tract infection (UTI) being other characteristics of the analysers. part of the top 10 diagnoses for which a Results: The following six POCT analysers were general practitioner (GP) is consulted in the evaluated: Uryxxon Relax (Macherey Nagel), Urisys Netherlands, urine test strip analysis to diag- 1100 (Roche), Clinitek Status (Siemens), Aution 11 nose UTI is a common diagnostic procedure on September 25, 2021 by guest. Protected copyright. (Menarini), Aution Micro (Menarini) and Urilyzer in general practice. Urine analysis takes (Analyticon). Analytical performance was good for all place in almost 2% of all consultations.1 analysers. Compared with laboratory reference standards, overall agreement was good, but differed Commonly, UTI is diagnosed based on the per parameter and per analyser. Concerning the nitrite test results for nitrite, leucocytes and erythro- ’ test, the most important test for clinical practice, all but cytes on the test strip, performed at the GP s one showed perfect agreement with the laboratory office by the GP nurse or midwife. Previous standard. For leucocytes and erythrocytes specificity studies have shown that, in general practice, was high, but sensitivity was considerably lower. negative test strip test results for nitrite and 2 1University Medical Center Agreement for leucocytes varied between good to very leucocytes are useful in excluding UTI. Utrecht, Julius Center for good, and for the erythrocyte test between fair and Professional guidelines in the Netherlands Health Sciences and Primary good. First-time users indicated that the analysers were recommend performance of a test strip Care, Utrecht, The easy to use. They expected higher productivity and evaluation of urine in case of a clinical suspi- Netherlands accuracy when using these analysers in daily practice. 2 cion of UTI. In case of a nitrite negative test Saltro, Diagnostic Center for Conclusions: The overall performance and Primary Care, Utrecht, strip result, the presence of leucocytes and user-friendliness of all six commercially available The Netherlands POCT urine analysers was sufficient to justify routine erythrocytes is assessed. If one of these is positive, a (semi)quantitative urine culture Correspondence to use in suspected urinary tract infections in general Dr Rogier M Hopstaken; practice. needs to be performed for conclusive 3 [email protected] diagnosis. Schot MJC, et al. BMJ Open 2015;5:e006857. doi:10.1136/bmjopen-2014-006857 1 Open Access BMJ Open: first published as 10.1136/bmjopen-2014-006857 on 18 May 2015. Downloaded from For urine analysis, a test strip for various tests is Healthcare, Munich, Germany), Aution 11 and Aution dipped in urine. After contact with the urine, the col- Micro (both Menarini Diagnostics, Florence, Italy) and oured pads of the test strip for analysis of nitrite, leuco- Urilyzer (Analyticon Biotechnologies AG, Lichtenfels, cytes, protein, glucose, ketones, urobilinogen, bilirubin Germany). All analysers qualitatively and semiquantita- and erythrocytes (dependent of the type of strip used), tively measure blood, urobilinogen, bilirubin, protein, can be assessed visually by comparing them to a colour nitrite, ketones, glucose, pH, specific gravity and leuco- chart most frequently printed on the side of the bottle cytes. Additionally, the Clinitek Status, and Aution 11 and containing the test strips. Visual inspection of test strips Aution Micro, can also measure albumin and creatinine. is subjective and errors may occur due to a variety of The different device characteristics are set out in table 1. reasons, including poor technique and poor, inadequate or untimely reading of the test results.45It has been sug- Laboratory reference standard gested that the use of point of care testing (POCT) We used the Urisys 2400 automated urine analyser urine analysers will increase the quality of urinalysis.67 (Roche Diagnostics Ltd, Rotkreuz, Switzerland) as the With the introduction of commercially available POCT laboratory reference standard for the six different POCT urine analysers, it may be possible to improve the quality urine analysers. Performance of the reference standard – of urinalysis in general practice. These analysers, there- has previously been proven to be good.9 11 This analyser fore, need to have good analytical performance and is routinely used for all (primary care) urine samples at agreement with laboratory standards, but data are Saltro Diagnostic Centre (Utrecht, the Netherlands). lacking for the different parameters. We set out to test, The Urisys 2400 test strips are measured 60 s after pipet- as the primary outcome measure, analytical perform- ting of the sample onto the test areas. Green and ance and agreement of six POCT urine analysers on orange LEDs are used for the evaluation of the reactive nitrite, leucocytes and erythrocytes, compared with test areas. Compensation of the intrinsic urine colour is laboratory standard reference tests. Furthermore, as sec- carried out using the reflectance value of the compensa- ondary outcome measures, user-friendliness, costs and tion pad for the green LED. Urine colour result is other characteristics of the analysers were compared. determined by using the reflectance values of the com- pensation pad for three wavelengths (orange, green and blue). Measuring an internal reference plate along with METHODS each test strip measurement automatically compensates Setting and samples potential influence of varying ambient temperature on All testing procedures were performed at Saltro the test results. The Urisys 2400 measures pH, leuco- Diagnostic Centre, an accredited diagnostic centre that cytes, nitrite, protein, glucose, ketones, urobilinogen, provides laboratory and other diagnostic services in bilirubin, blood (erythrocytes/haemoglobin), clarity and http://bmjopen.bmj.com/ routine primary care for approximately 850 GPs, and specific gravity. over one million inhabitants. We collected 77 urine We used the Sedimax urine analyser (Menarini, samples of patients who delivered a urine sample Florence, Italy) as additional reference standard for for routine investigation at one of the four participating quantitative evaluation of leucocytes, erythrocytes and general practices. Samples were stabilised using sediments, to verify the quantitative results of the differ- laboratory tubes containing Stabilur (Greiner BioOne, ent urine test strip POCT analysers. Analytical and diag- Kremsmuenster, Austria). Urine samples are transported nostic performance of the Sedimax urine analyser has from various locations (GP offices and blood draw loca- 12 13 previously been proven to be good. on September 25, 2021 by guest. Protected copyright. tions) to the central laboratory for analysis. Saltro Diagnostic Centre routinely uses Stabilur to preserve Analytical performance urine samples for particle counting. Stabilur preservative To assess within-day and between-day performance, a tubes are acceptable for test strip analysis within 8 h on protocol was used based on the clinical and laboratory