Automated urine screening devices make urine sediment microscopy in diagnostic laboratories economically viable
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Zahur Zaman
Abstract
Automated urinalysis devices are reproducible, accurate and faster than the standard manual microscopy. Economic analysis has shown that decreases in turn-around-time and labour cost savings offered by these devices make them more economic than manual microscopy.
Introduction
Diagnostic screening of urine samples is the third most frequently performed analysis in clinical laboratories. Traditionally, urinalysis comprises two parts; analysis by a test strip and visual microscopy of the urine. Although standardisation of the pre-analytical and the analytical procedures has improved the quantitative results of the formed elements – particularly when present in low numbers, manual microscopy examination of urine sediment is a time-consuming and labour intensive method with limited precision and it is prohibitively expensive to implement in cash-constrained clinical laboratories. Recent development of automated urine analysers has provided a more precise and relatively low cost alternative to manual microscopy.
Recently, National Health Service (NHS) Purchasing and Supply Agency’s (PSA) Centre for Evidence-based Purchasing (CEP) reviewed the literature and compared the currently available automated urinalysis devices against manual laboratory techniques [1]. The review endeavoured to clarify whether any of the automated systems could produce results comparable to those obtained by manual microscopy. The review identified three devices whose operations complied with the published guidelines for urinalysis [2, 3]. These devices were IRIS iQ200 (IRIS Diagnostic UK Ltd., Cambridge, UK), Sysmex UF-1000i (bioMerieux UK Ltd., Basingstoke, UK) and SediMax (A. Menarini Diagnostics Ltd., Wokingham, UK).
Materials and methods
The PSA evaluated the use of these devices in comparison with manual microscopy by sending a questionnaire to 250 diagnostic laboratories across the UK [4]. The questionnaire elicited information about the method of urinalysis in each laboratory, perceived time and economic efficiencies.
Results
Completed questionnaires were returned by 103 (41%) laboratories. All but three used one of the above mentioned automated devices.
These were the results of the questionnaires:
78% of the laboratories using an automated device recorded an increase in the number of samples analysed per day. In 88% laboratories, turn-around-time for the results had decreased.
Service users’ confidence in the service stayed the same or increased. However, 28 laboratories did not know what effect, if any, the automated urine screening had on the users’ confidence.
Automated urinalysis was found to give better reproducibility, accuracy and decreased analysis time. Overall less staff were required and the skill-mix had shifted to less qualified staff. In 55% laboratories staff were deployed to other tasks and 32% laboratories needed less staff.
For 74% of the laboratories visualising the formed elements was important or essential.
Loss of skill of identifying the formed element was considered a serious disadvantage of the automated systems.
Economic analysis
As adequate and uniformly performed economic calculations for each of the three automated urine analysers do not exist, the PSA carried out a detailed economic analysis to compare each automated system with the manual microscopy method [1]. For these calculations, standard life time of equipment was assumed to be 7 years with 2 years of warranty. Some of the other assumptions made in the calculations are shown in Table 1. The results of the cost analysis and the formulae used to calculate total cost per test are shown in Table 2.
Assumptions made in economic analysis.
| Assumptions | Effect of deviation from assumption |
|---|---|
| Time taken and costs for QC in all methods is the same | The method that takes more staff time or costs for QC will have increased cost/test |
| Facility costs (space, etc.) are the same for all methods | If space, cleaning and drainage costs are considered, automated systems may incur some added cost |
| Workload is effectively spread through the day by variable TAT | User survey indicated that actual workload varies through the day, so the efficiency of an automated system may spread over a period of time when busiest, but that machines are in use continually. This may result in less efficient use during slower periods. |
| Utility costs (water, electricity) are equal for manual and automated methods | The cost/test will increase for the method that uses more resource |
| TAT is not considered as a cost | There may, in fact, be an effective cost due to business lost or inefficiencies introduced if TAT increases significantly |
QC, quality control; TAT, turn-around-time.
Calculated cost per test.a
| Manual microscopy | Automated microscopy (range) | |
|---|---|---|
| Assistant minutes/test | 0 | 0.2–0.4 |
| Scientist minutes/test | 2.7 | 0.05b |
| Purchase costc | £4300 (estimated) | £31,000–58,000 |
| Annual service charge | £650 (estimated) | £4500–7000 |
| Consumables/test | £0.143 | £0.30–0.31 |
| Resultant total cost/test (n=100 samples/day) | £1.37 | £0.60–0.80 |
| Cost/test, n=200 | £1.37 | £0.48–0.60 |
| Cost/test, n=400 | £1.37 | £0.42–0.50 |
| Cost/test, n=600 | £1.37 | £0.40–0.47 |
aTotal cost per test=(staff costs+machine costs+consumable costs) per test. Staff cost/test=(Assistant cost/min×effective minutes/test)+(Scientist cost/min×effective minutes/test). Where, effective minutes/test=(actual minutes for Y samples)/Y. Machine cost/test=purchase and maintenance cost/number of tests in life time of machine. Machine cost/test=([purchase price]+5×[annual maintenance charges])/([actual number of tests per day]×[lifetime days]). Where, actual number of tests per day=(number of samples supplied)+(number of repeat samples needed). Consumable cost/test=([consumables/test]+[quality control (QC) per day])/(number of tests per day). For calculating the staff cost, annual total time worked by staff was assumed to be 220 days and that the staff worked 7.5 h/day. Total annual work time in minutes=220×7.5×60 min=99,000 min. Assistant cost/minute=£Salary/99,000. Scientist cost/minute=£Salary/99,000. Assumed lifetime of equipment in days=7 years, running for 6 days per week on average=(7×6×52)=2184 days; bThis figure is based on 15% expert review rate and 20 s per review; cPurchase prices may not be valid any longer.
As labour costs can contribute up to 70% of the cost/test, it is evident that automated microscopy is much cheaper than manual microscopy at all levels of workload. The times of 2.7 min/test for manual microscopy and 20 s/expert review can only, reasonably, be applicable to the UK laboratories where urine sediment examinations, in general, occur in microbiology laboratory and they are mostly limited to looking for erythrocytes, leukocytes and bacteria. More extensive examination of urine by a trained technologist, in the author’s laboratory ranged from 5 to 7 min–depending on the complexity of the sample. Correcting the figures in Table 2 for these reservations will increase the cost/test differential still more in favour of automated microscopy.
Discussion
Review of the published evidence identified three automated systems, namely, Sysmex UF 1000i (and UF-50 and UF-100), IRIS iQ200 and SediMax, that can be used for screening urine samples. The results from these devices correlate well with the manual methods, and strongly improve the reproducibility and have acceptable sensitivity for the detection of important formed elements [1]. However, these systems are not yet capable of identifying a number of important urinary particles, such as renal tubular epithelial cells, transitional epithelial cells, lipids and some types of casts. In addition, optimum levels of cut-off values are not clear in the literature and the three currently available automated devices have not been compared with the manual microscopy in the same study. Therefore further studies are needed to compare these devices in the same trial and to determine acceptable figures for cut-off values for all formed elements found in the urine.
The laboratories and the users of the laboratory services in the UK were largely satisfied with the performance of the automated devices, although a strong preference was shown for the systems capable of visualisation of the formed elements in the urine samples [4]. Now that phase-contrast imaging has been added to the existing bright-field microscopy to SediMax, this could give a competitive advantage to this analyser.
Considerable economic savings reported [1] by the laboratories in the UK were achieved by the reduction in analysis time per test, staff shedding and move to lower skilled staff needed to perform urine sediment analyses. In addition to this, by decreasing turn-around-time, the automated devices potentially enable quicker diagnosis. This could lead to wider cost savings in other departments due to earlier patient discharge or surgery. However, in any comparative cost analysis, a laboratory must consider what other tasks can benefit from the time freed up by automation, as skills must be retained for use when needed (e.g. visual confirmations and manual reviews). If other useful tasks do not exist as, e.g. in a small laboratory, the time saved will not be economically usefully employed.
The figures in Table 2 suggest that the pay-back time for the purchase of an automated system (i.e. the time taken for cost-savings to equal the cost of purchasing the equipment) would vary between 2 and 40 months. This range is well within the expected life time of the analyser.
In conclusion, even if cost of purchasing the automated urinalysis devices increase significantly, the redeployment of staff and lower grade of staff needed to run these devices would still make them more economical than manual microscopy.
Author contributions: The author has accepted responsibility for the entire content of this submitted manuscript and approved submission.
Financial support: None declared.
Employment or leadership:None declared.
Honorarium: None declared.
Competing interests:The funding organisation(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
References
1. CEP 10030. Evidence review, automated urine screening systems, 2010.Search in Google Scholar
2. European Urinalysis Guidelines. Scand J Clin Lab Invest 2000;60(Suppl 231):1–96.10.1080/00365513.2000.12056993Search in Google Scholar
3. Investigation of urine. National Standard Method BSOP 41 Issue 7. Health Protection Agency, 2009.Search in Google Scholar
4. CEP 10031. Evaluation report, automated urine screening systems, 2010.Search in Google Scholar
©2015 by De Gruyter
Articles in the same Issue
- Frontmatter
- Editorial
- Urinary sediment: still an important diagnostic tool
- Introduction
- A history of urine microscopy
- The modern view on some urinary sediment particles
- Lipiduria – with special relevance to Fabry disease
- Cylindruria
- Crystalluria
- External quality control programs on urinary sediment
- External quality assessment of urine particle identification: a Northern European experience
- The Italian External Quality Assessment (EQA) program on urinary sediment: results of the period 2012–2015
- Recent advances in the automation of urinary sediment analysis
- Screening of presumptive urinary tract infections by the automated urine sediment analyser sediMAX
- Automated urine screening devices make urine sediment microscopy in diagnostic laboratories economically viable
Articles in the same Issue
- Frontmatter
- Editorial
- Urinary sediment: still an important diagnostic tool
- Introduction
- A history of urine microscopy
- The modern view on some urinary sediment particles
- Lipiduria – with special relevance to Fabry disease
- Cylindruria
- Crystalluria
- External quality control programs on urinary sediment
- External quality assessment of urine particle identification: a Northern European experience
- The Italian External Quality Assessment (EQA) program on urinary sediment: results of the period 2012–2015
- Recent advances in the automation of urinary sediment analysis
- Screening of presumptive urinary tract infections by the automated urine sediment analyser sediMAX
- Automated urine screening devices make urine sediment microscopy in diagnostic laboratories economically viable
