DLD - Allan L. Truant, PhD Jamshid Moghaddas, MS, RM(AAM)...

LABORATORY MEDIC INE VOLUME 31 , NUMBER 5 MAY 20 0 022 66 66

Recently, a heightened sense of interest has beenexpressed in clinical laboratory medicine in allareas of cost containment and optimization of testmenus, recording modalities, and reporting proto-cols. In part, the increased presence of managedcare agreements and the omnipresent merger-and-acquisition environment in the health caresector have influenced this. (Although, to a certainextent, this interest has always been present inthose individuals supervising and directing clini-cal laboratories.1) Nevertheless, with each passingyear, it becomes increasingly important to moni-tor the efficiency of one’s laboratory and to maxi-mize the clinical usefulness of all laboratoryresults provided.2 A number of studies have:

■ outlined the usefulness of limiting the numberof specimens submitted to the microbiologylaboratory,3,4

■ described the acceptability of specimens, or■ presented flexible staffing options.5

The monitoring and evaluation of the numberof tests performed and the actual workload of alaboratory have both been factors used by labora-tory directors and administrators to study the effi-ciency of the laboratory. Throughout the past 20to 30 years, College of American Pathologists(CAP) workload units, initially developed as aworkload recording system by the Canadian Asso-ciation of Pathologists, have been used sporadi-cally in the United States, in other North Americanlaboratories, and at selected institutions abroad.6-8

They have been a useful means, at times, to evaluate

Allan L. Truant, PhDJamshid Moghaddas, MS, RM(AAM)Edna D. Williamson

MM AA NN AA GG EE MM EE NN TT

Using College of AmericanPathologists Workload Units forIntralaboratory Comparison

At Temple University Hospital, a 504-bedurban teaching hospital, we have adapted the

College of American Pathologists (CAP) workload units fromthe last published guidelines of the 1992 format to the 1998Meditech Laboratory Information System MAGIC, version4.6 (Westwood, MA). At our institution, the laboratoryinformation system was interfaced with the hospitalinformation system—Eclipsys 7000 Series (Atlanta). CAPworkload units were adapted for the clinical microbiologyand immunology laboratories, which include bacteriology,mycology, parasitology, mycobacteriology, virology, andmicrobial immunology laboratories. All tests and proceduresin the clinical microbiology and immunology laboratorieswere assigned workload unit values and were compared withworkload unit values using the 1992 guidelines. Workloadunit values for most procedures were incorporated directlyinto the Meditech Laboratory Information System; values forgeneral laboratory support procedures such as qualitycontrol, phone calls, gowning, gloving, degloving, and othergeneral procedures were incorporated monthly. Databasessuch as this can be quite useful in monitoring monthlyworkload trends, increases in workload due to laboratorymergers and acquisitions, and intralaboratory annuallaboratory statistics.

ABSTRACT

From the Department of Pathology and Laboratory Medicine (Dr Truant), andClinical Microbiology and Immunology Laboratories, Temple University Hospitaland School of Medicine, Philadelphia.

Reprint requests to Dr Truant, Director, Clinical Microbiology and ImmunologyLaboratories, Department of Pathology, Temple University Hospital, 2 ParkAvenue Pavilion, Broad and Ontario Streets, Philadelphia, PA 19140; or e-mail:[email protected]

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MAY 20 0 0 VOLUME 31 , NUMBER 5 LABORATORY MEDIC INE 22 66 77

workload and efficiency in a particular laboratoryand to occasionally compare one laboratory withanother.9 However, imprecise evaluations andoccasionally improper comparisons have alsobeen made due to:

■ incorrect or outdated workload estimates,■ omission of certain laboratory activities, or ■ different workload unit calculations made at dif-ferent institutions.

We have attempted to evaluate and update the1992 CAP workload units for the bacteriology,virology, mycobacteriology, mycology, parasitol-ogy, and immunology laboratories. The workloadunits were adapted to the 1998 Meditech Labora-tory Information System MAGIC, version 4.6(Westwood, MA), and the laboratory informationsystem (LIS) was interfaced with the Eclipsys 7000Series (Atlanta), which is the hospital informationsystem used at our institution.

Although this article deals with workload mea-surements in the clinical microbiology andimmunology laboratories, the same methodologyis easily applicable to other laboratory areas. Atthis institution, all clinical laboratories have incor-porated CAP workload units into the LIS similarto the clinical microbiology and immunology lab-oratories. In part, however, owing to the stilllargely manual component for many microbiol-ogy procedures, this approach is particularly usefulfor those laboratories.

MMaatteerriiaallss aanndd MMeetthhooddssDesign of Meditech Workload ProfileThe Meditech LIS requires each laboratory (orsection) to be defined using a specific identifier(eg, MICROBIOLOGY, CHEMISTRY, HEMATOLOGY). Eachlaboratory within microbiology is further dividedinto subsections, followed by an abbreviation (inparentheses and known as a “mnemonic”) as fol-lows: bacteriology (MB), virology (MV),mycobacteriology (MT), mycology (MM), para-sitology (MP), and immunology (MI). Withineach subsection, a group of related tests is definedand given an appropriate abbreviation as part ofan expanded mnemonic. For example, a test for

grouping of streptococci was defined as “MB STR-GRO,” and a test for antinuclear antibody by fluo-rescent antibody was defined as “MI IFAANA.” Atthis point, all clinical laboratory tests were evalu-ated, and specific CAP workload values wereassigned to each function (eg, accession, plating,bacterial identification, or antimicrobial suscepti-bility test) within each test, followed by assign-ment of CAP workload values to each test (eg,sputum culture or urine culture). Many workloadvalues were available in the last published guide-lines of the CAP.10 Those activities that were notpreviously described in these guidelines were eval-uated by a panel of clinical microbiologists (direc-tor, supervisor, and senior medical technologist)and assigned a new workload unit value. Eachactivity was evaluated individually and, when pos-sible, compared with previously published similarfunctions in the CAP workload recording manual.A time average was taken for each laboratory func-tion, and only the new workload values areincluded in this report.

As each specimen is accessioned into the LIS(ie, in our hospital, the Meditech LIS), the specificworkload units are captured by the LIS for eachfunction (eg, accession, streaking of plates, read-ing of plates). All negative tests will receive theidentical workload for that test (or procedure).Those specimens that are positive will have addi-tional functions recorded in the LIS, such as bac-terial identification and antimicrobial susceptibilitytest. Once the test is complete and the result final-ized, the LIS will capture and record the total of allworkload units that were entered for each func-tion within each test. For those special functionssuch as quality control, gowning, degloving,inventory, phone calls, freezing organisms—all ofwhich are classified as “undefined activities,” thesupervisor enters these workload units into theLIS on a monthly basis.

RReessuullttssMany of the CAP workload units for each majorfunction and for conventional microbiology testsare contained in the CAP workload and recordingmanual.10 Those functions that did not have aworkload assigned to them were assigned work-load units after evaluating the function in our lab-oratory. Many previously undefined activities didnot have workload units available. These activities

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were evaluated, and the workload units aredepicted in Table 1.

Each laboratory procedure (consisting of mul-tiple activities and functions) was then assigned aworkload unit value that consisted of all the func-tions within the procedure. These values areshown in Table 2. Quality control and instrumentmaintenance workload units were evaluated, andselected units are depicted in Table 3. In thesetables we have not included CAP code numbersor the specific mnemonic used; however, we havelisted the recommended workload value so thatany laboratory can easily adapt this approach toits own LIS.

A number of workload values have not beenincluded in this report owing to the large numberof values that are included in the microbiologyand immunology laboratories. Examples of valuesnot included are mycology, parasitology,mycobacteriology, and virology quality controlworkload units. The workload values for acces-sioning specimens were developed as separatecomponents and included in the total workloadvalue for each specific test. These values are notseparately included in this article; however, theymay be of specific value for those laboratorieswishing to evaluate the workload activity identi-fied as “accessioning” in a particular laboratory.

DDiissccuussssiioonnA number of methods are currently available inthe clinical laboratory to address the issue of effi-ciency. One of the most obvious and usefulapproaches is to incorporate an up-to-date LIS.11

The purpose of this communication is not toreview the wide availability and relative strengthsof each of the clinical LISs currently available. Noris our purpose to review the breadth of personnel

standards and quality of laboratory work. Rather,we have attempted to adapt the most currentlyavailable CAP workload units to one widely avail-able LIS: the Meditech LIS. We have reported theprecise methods and values that have beenassigned to each laboratory test. This laboratoryhas found the use of updated workload units to bequite useful in monitoring intralaboratory trends.Other laboratories can adapt this approach to anyLIS using the same or similar workload units.

In 1992, the CAPdecided to expand the CAPLaboratory Management Index Program (LMIP)and to use the productivity indices in that pro-gram. It was thought that LMIP would be areplacement for the CAP Workload RecordingMethod. In 1992, with few exceptions, there wereno plans by the CAP to make additional updatesto the Workload Recording Method; further, theCAP decided not to publish a 1993 WorkloadRecording Method and Personnel ManagementManual. It was recommended in 1992 that thoselaboratories using the Workload RecordingMethod continue using this method until the newLMIP’s productivity module was released.

The LMIP is a comparative management reportoffered by the CAP and is issued quarterly. It analyzesand compares a number of management factors thatinfluence a laboratory’s budget, productivity, andutilization. The LMIP is a benchmarking report thatprovides the participant with 5 LMIP reports:

■ an executive summary,■ a comparative performance report,■ an individual data summary,■ an external comparison report, and■ control charts.

The LMIP report utilizes an LMIP unit, whichwas introduced in an attempt to establish a com-mon base for making interlaboratory compar-isons. This approach attempts to remove billingand accounting differences between institutions.The LMIP report may be utilized for both intral-aboratory and interlaboratory comparisons.However, one must be particularly careful ofcomparisons made with different health caresystems, for example, rural community hospitalsvs academic medical centers vs multispecialtygroup practices.

Table 1. Workload Units for Undefined Activities

Laboratory Function Workload Value

Laboratory meeting 30.0

Storage 60.0

Inventory 30.0

Photocopying 10.0

Infection control/computer reports 30.0

Bench training (trainee) 420.0

Phone calls 5.0

Mail (city/state) 7.0


MAY 20 0 0 VOLUME 31 , NUMBER 5 LABORATORY MEDIC INE 22 66 99

The Workload Recording Method was beingde-emphasized due in part to:

■ It was thought that incorporating reliabletime studies for tests and instruments wasbecoming increasingly difficult, especially in theface of rapid technological changes in clinicallaboratory medicine.■ The workload values were becoming potentiallysuspect by department and hospital administra-tors owing to limited updating of information.■ Laboratory and administrative utilization of theWorkload Recording Method was not optimallyunderstood.

One of the problems with previous workloadrecording methods is that they did not capturenonbillable elements of the laboratory, such asquality control, infection control, employeehealth, and other laboratory procedures notordered for direct patient care. These elementsaccount for a significant percentage of personneltime and effort and also utilize supplies andreagents of the laboratory. In this report, we havereviewed our approach in incorporating many ofthese functions previously omitted from theWorkload Recording Method. We believe that theWorkload Recording Method is best suited forintralaboratory use and comparisons becausethere are so many variables unique to each labora-tory, test menu, and specific methodologies used.

We have incorporated the updated workloadrecording system, reported in this article, into ourlaboratory using the Meditech LIS. We have foundthis approach quite useful for intralaboratorycomparisons (ie, within microbiology andimmunology) and for month-to-month compar-isons. Because our medical center has beeninvolved in acquisitions and mergers in recentmonths, as have many others, the availability ofvolume data and workload unit data has been par-ticularly useful. Specifically, the availability ofworkload data that capture accessioning of speci-mens may be of particular benefit to high-volumelaboratories by identifying areas of heavy work-load and possible justification for new positions orchanges in staffing.

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Table 2. Workload Units for Defined Microbiology Procedures

Procedure* Workload Value

Bacteriology Culture

Anaerobic 25.4

Blood 20.0

Body fluid 20.4

CSF 20.4

GC 11.4

Infection control 21.4

Legionella 20.4

Routine 25.4

Sputum 20.5

Sterility 16.4

Stool 25.4

Throat, Strep A 11.5

Urine 12.5

Wound 25.4

Mycology

Fungal culture—negative 30.0

Fungal culture—positive 49.5

Yeast identification 25.5

Yeast screen 25.5

Parasitology

Cryptosporidium 23.0

O&P 28.0

Mycobacteriology

AFB culture—negative 30.0

AFB culture—positive 34.3

Virology

CMV culture evaluation 39.6

Viral culture, general—negative 28.7

Viral culture, general—positive 55.7

Culture, HSV—negative 18.5

Culture, HSV—positive 36.5

Culture, respiratory 76.2

Western blot 30.0

*General accession workload unit is defined as 1.7; workload units forplating will vary, depending upon the number of agar plates used.

AFB indicates acid-fast bacilli; CMV, cytomegalovirus; CSF, cerebrospinalfluid; GC, Neisseria gonorrhoeae; HSV, herpes simplex virus; O&P, ovaand parasites.



In addition to the use of workload recordingmethods as a tool to monitor and improve labora-tory efficiency, we have also recently implementedthe use of bar coding in our clinical microbiologylaboratory to improve these functions. The pri-mary advantage of bar coding has been to mini-mize the time needed at the bench level to recorddemographic information and results. Secondarypurposes have been at the instrument level tominimize specimen handling and labeling. Othershave reported the usefulness of bar coding in theclinical microbiology laboratory setting.12 Inaddition to the use of LIS, bar coding has helpedto minimize the efforts required to process andreport specimens in all microbiology andimmunology laboratories.

At the present time, there are so many variablesin the workload recording system, and becauseprocedures still vary widely between laboratories,we would not recommend comparing workloadunits from one laboratory to another. However,comparing month-to-month variation within alaboratory or even technologist-to-technologistvariation within a laboratory may be of some use.

The most consistently useful place for these fig-ures appears to us to be month-to-month andyear-to-year variations within a laboratory. Whenand if laboratories can standardize their proce-dures, the system may (in the future) be adaptableto use for comparisons of laboratory to labora-tory. In specific circumstances, ie, identical proce-dures (usually automated techniques) it may beused for interlaboratory comparisons. Whetherthe evaluation is used for intralaboratory compar-isons (current recommendations) or for interlab-oratory comparisons (possible future use),periodic assessment and modifications will, ofcourse, be required when the technology changesfor a specific test, method, or instrument.

This approach may be useful to those labora-tories utilizing the Meditech LIS and for otherlaboratories using a similar LIS. The valuesdetailed in this report may be adapted for use inother systems.l

References1. Bartlett RC, Rutz C. Processing control and cost in bacte-

riology. Am J Clin Pathol. 1980;74:287-296.2. Wilson ML. Clinically relevant, cost-effective clinical

microbiology: strategies to decrease unnecessary testing. Am JClin Pathol. 1997;107:154-167.

3. Siege DL, Edelstein PH, Nachamkin I. Inappropriate testingfor diarrheal diseases in the hospital. JAMA. 1990;263:979-982.

4. Valenstein P, Pfaller M, Yungbluth M. The use and abuse ofroutine stool microbiology: a College of American PathologistsQ-Probes study of 601 institutions. Arch Pathol Lab Med.1996;120:206-211.

5. Phillips SE, Atherton C. Flexible staffing in the microbiol-ogy lab. MLO. May 1997: 61-63.

6. Koss W, Sodeman T. The workload recording method: alaboratory management tool. Clin Lab Med. 1992;12:337-350.

7. Norbut AM, Foulis PR, Mendelow H. Workload recordingby microcomputer. Am J Clin Pathol. 1980;74:469-471.

8. Penner DW, Sinton EB. The application of measurementsystems in the management of medical laboratories. Clin LabMed. 1983;3:553-570.

9. Cundy KR. CAP workload recording: the enemy may be us.Clin Microbiolo Newsletter. 1987;9:3-5.

10. College of American Pathologists. Workload RecordingMethod and Personnel Management Manual, 1992. Northfield,IL:College of American Pathologists; 1991.

11. Elevitch F, Treling C, Spackman K, et al. A clinical labora-tory information systems survey: a challenge for the decade.Arch Pathol Lab Med. 1993;117:12-21.

12. Willard KE, Shanholtzer CH. User interface reengineer-ing: innovative applications of bar coding in a clinical microbi-ology laboratory. Arch Pathol Lab Med. 1995;119:706-712.

Table 3. Selected Workload Units for Quality Control and Instrument Maintenance

Procedure Workload Value

Imx, daily 15.0

Imx, weekly 30.0

Imx, monthly 15.0

Kirby-Bauer, daily 45.0

Labotech, weekly 5.0

Labotech, monthly 5.0

Plate media, weekly 84.8

Quantum, monthly 30.0

QwikWash, daily 2.0

Recording media, weekly 11.0

Thyroid antibody 40.0

Toxoplasma antibody 4.8

Vitek, daily 65.0

Western blot 27.0

Imx, Quantum, and QwikWash are manufactured by Abbott Laboratories,Abbott Park, IL; Labotech, Biochem Immunosystems, Allentown, PA; Vitek,bioMerieux, Hazelwood, MO.


J Clin Pathol 1985;38:208-214

A study of workload units in five microbiologylaboratoriesRY CARTWRIGHT,* JOAN R DAVIES,¶ C DULAKE,t RJC HART,t CA MORRIS,§PJ WILKINSONII

From the Public Health Laboratories, *St Luke's Hospital, Guildford, tWilliam Harvey Hospital,Willesborough, Ashford, Kent, tHeavitree, Exeter, §Royal Shrewsbury Hospital, IlDerrford Hospital,Plymouth, and the ¶Public Health Laboratory Service Board, Head Office, Colindale, London NW9

SUMMARY A study of a modified Canadian unit system of measuring laboratory workload wasundertaken in five joint Public Health Laboratory Service and hospital microbiology laboratories.Ten percent of the specimens received over six months were sampled, the number of unitsexpended on each was recorded, and the results were analysed on a central computer. Theprocess of gathering information in the absence of laboratory computers was time consumingand, despite careful planning, differences were found in the recording practices of thelaboratories. The analysis of results did not lead to major changes in data gathering techniquesbecause the same information about laboratory workload could be obtained by collecting num-bers of clearly defined specimens. Analysis of workload units could be useful for particularpurposes, such as comparing differences between laboratories using different techniques for thesame investigation or assessing the possible benefits of automation. It must be appreciated,however, that workload units are measures of quantity not of laboratory performance.

For some years there has been dissatisfaction withthe methods of assessing laboratory work. Theyhave been criticised as being both inaccurate anduninformative. Attempts to improve the methodshave led in Britain to redefinitions of requests andspecimens and in North America to the use of work-load units. These different approaches may be areflection of the different methods of financinglaboratory work.The complexity of microbiological investigations

compared with the more stereotyped and mechan-ised techniques used in haematology and chemicalpathology make for more difficulty in workloadmeasurement. In general, the information requiredof a microbiology laboratory is the total workload,the distribution of specimen types, and the workentailed in the examination of each type. It may alsobe desirable to record the source of specimens andto provide a means of costing the examination. Noneof these measurements is of any value unless themethod of calculating the workload is reliable,reproducible, and provides for uniformity betweendifferent types of specimen and between different

Accepted for publication 9 October 1984

laboratories. Within the laboratory this informationis necessary for the best allocation to be made ofmanpower and space. It should be sufficiently pre-cise to enable assessment of trends in workload lead-ing to the review of methods so as to provide, forexample, information on the cost effectiveness ofautomation.

Health authorities need information to allocateresources between laboratories more rationally. Ifcosting of laboratory services to particular users,such as individual clinical disciplines, can be madesufficiently accurate, realistic forecasts of theresource requirements of the laboratory can bemade to accommodate changes in clinical workload.Accurate statistics of workload would be of particu-lar value to the Public Health Laboratory Service(PHLS), in which there are a number of closelycomparable laboratories, because they would pro-vide opportunities for the evaluation of differentmethods and techniques as well as providing theadministrative information already discussed.

Before the present study, discussion in Britain'about the Canadian unit system2 of measuring work-load led to an experimental assessment of unit work-load measurement in pathology by the South West-ern Regional Health Authority (SWRHA). A

208

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A study of workload units in five microbiology laborat

number of combined PHLS and hospitallaboratories were involved in the application of thisproject to microbiology, the funding of which ceasedafter much preliminary work had been done. Thisinformation was made available to us, and a sixmonth pilot study of a modified Canadian unit sys-tem of workload measurement was carried out infive laboratories, each of which provided a diagnos-tic service and examined food and other environ-mental specimens. The units were based on techni-cal time only; no consideration was given to over-heads, the employment of other staff, or the capitaland revenue costs of equipment. Each laboratorycollected its own data, which were analysed by thecomputer services department of the PHLS.

tories 209

Table 1 Examples ofallocation ofworkload units (WL U)to laboratory tests

Test WLU Test WLU

Microscopy Confirmatory testsGram film 3 Coagulase (tube) 3Dark ground 10 Indole production 2Fluorescence 5 Nagler plate 8Wet film 2 Sugar fermentation

(per substrate) 1Procedures Sensitivity tests

Centrifugation 1 Direct 2Slide agglutination 2 On culture 3Dilution series 4 Stokes' plate 4

Culture EnvironmentalAerobic plate 1-5 Methylene blue test 4Anaerobic plate 2 Membrane filtration 4Enrichment 1 Weighing andFor tuberculosis 5 homogenisation of food 10

Pour plate 5

Methods

The participating laboratories all performed a widerange of microbiological investigations employingcommonly used manual methods at the time of thesurvey, which were broadly comparable for each.Two of the laboratories examined about 60 000

specimens a year, two examined about 100 000, andone 140 000.The examination of a specimen implies the per-

formance of a number of laboratory manoeuvres

P. H.; L. EXETER WS/241/50/01

CLER'CAL 037

VISUAL EXAMINATION 262

HOMOGENISATION 093

LIQUEFACTION/DIGESTION 131

METHYLENE BLUE STAIN 155

DIRECT BLOOD AGAR 02 043

CO2 044

AnO2 044CHOCOLATE AGAR CO2 '044

CLED 043

McC 043

NALIDIXIC BLOOD AGAR 044

MANNITOL SALT AGAR 043

SAB C 270 043

.,370 043SUCROSE BROTH 045

MYCOPLASMA MEDIUM 044

BROTH CULTURE 045

GRAM (SPECIMEN) 153ZN (SPECIMEN) 161

EOSINOPHIL STAII4 154CENTRIFUGE 034

WET PREP (DIRECT) 159

READ DIP SLOPE 054

WET PREP (SPUN DEPOSIT) 159 _SENSITIVITY (DIRECT) 370 223., 300 223

(CULTURE) 370 224 __

Fig. 1 Example ofa backing sheet.

SPUTA AND SPECIMENS FOR T.B.

SENSITMVITY ( CULTURE) 30' 224STOKES PLATE 225BLOOD AGAR SUB 02 043

CO2 044AnO2 044

GRAM (CULTURE) 153

X+'VDISCS 280BETA-LACTAMASE 021

OPTOCHIN 182

BILE SOLUBILITY 023

SLIDE COAGULASE 039

TUBE COAGULASE 040

UREA 251

AESCULIN 001

OXIDASE 184

GERM TUBE 082

NaOH TREATMENT 242

LJ PLAIN 370C 046PYRUVATE 370 C 046PLAIN 300 C 046PYRUVATE 300 C 046KIRCHNER 046

ZN (CULTURE) 160

LI 250C 046370 C (DARK) 046370 C (LIGHT) 046450C 046

OXYGEN PREFERENCE 045

DATE IN OUT

LAB. NUMBER

G.P. HOSP. HOSP. ENV. OTHER

TELEPHONED REPORT 241 |

SEND FOR PHAGE TYPING 183

" " FUNGUS 183

" " HISTOLOGY 183

" CYTOLOGY 183

REF. LAB. (EXTERNAL) 210

PED

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210

(tests), which may involve microscopy, culture on avariety of media, subculture, characterisation oforganisms, assessment of antibiotic sensitivity, thequantitative assessment of antibodies to a number ofantigens, and so on. A list of all tests performed bythe participating laboratories was prepared and eachtest was allocated a three digit code, a name, and ascore of notional workload units (WLU). Thesescores were allocated by one of three methods: (a)acceptance of the units given in the Canadian sys-tem2; (b) adoption of the unit value worked out inthe South Western Regional project; and (c) prep-aration of new scores for tests or methods for whichno unit values were available.When method 3 was used the tests were carried

out in at least two laboratories by several membersof staff with differing degrees of experience. Theunit value for each test was the average number ofminutes required to carry it out. The scores, how-ever derived, were agreed by the participatinglaboratories. Where different laboratories used dif-ferent methods to perform a test, an appropriatescore of WLU was allocated to each method. Exam-ples of the WLUs are shown in Table 1.Specimens were classified into 14 groups and for

each group an appropriate backing sheet wasdesigned listing the tests likely to be used (for exam-ple, see Fig. 1). Additional sheets were used iffurther tests were necessary. The specimencategories were: urine, upper respiratory, lowerrespiratory, genital, wound, blood culture, cere-brospinal fluid, faeces, mycology, tuberculosis, gen-eral bacteriology, serology (including viral sero-logy), virus isolation, and environmental microbiol-ogy (including food, milk, water). Specimensreceived for external quality assurance wereincluded in the appropriate categories. Throughoutthe study all specimens were allocated laboratorynumbers by the system normally used in thelaboratory. The request form accompanying every10th specimen in each numbering series wasattached to the appropriate backing sheet. Membersof the laboratory staff ticked the appropriate tests

Table 2 Comparability oflaboratories: specimens andworkload units (WLU)

Laboratory Total Specimens Mean WLU Total annualspecimens assessed per specimen WLUper annum* (thousands)

A 58 640 2932 19-53 1145B 61480 3074 13-19 811C 93 840 4692 16-09 1509D 96 800 4480 15-72 1522E 131 460 6573 13-88 1825

*Estimated from a 10% sample over 25 weeks.

Cartwright, Davies, Dulake, Hart, Morris, Wilkinson

on the backing sheet while the specimen was underexamination.When work on each specimen in the survey was

complete and the report signed, the backing sheetswere separated and sent in weekly batches to thecomputer services department of the PHLS. Therethe scores of WLU were added to the sheets and theinformation processed on a CTL 8046 computer(Computer Technology Ltd, Hemel Hempstead,England). None of the participating laboratories hada local computer facility.

Results

All five participating laboratories provide a generalmicrobiology diagnostic service predominantly forthe examination of clinical specimens, of whichabout 70% were from hospitals and the remainderfrom other sources; these included a small numberof non-clinical specimens such as milk, water, andfood. Table 2 shows for each laboratory the esti-mated annual workload (calculated from the 25week study period) expressed in terms of specimensand units. The proportion of different categories ofspecimen sampled and workload units generated bythem in each laboratory is shown in Fig. 2. Asexpected, there was some variation betweenlaboratories but the patterns showed no appreciabledifferences and all five laboratories could beregarded as broadly comparable in the source andtype of specimen and proportion of samples in eachdefined category.For each category the mean workload units per

specimen was calculated for each laboratory and forall laboratories. Fig. 3 shows the variation aboveand below the group mean. The specimens aredivided into three groups: (a) those in which there islittle variation between laboratories-for example,upper respiratory and urine; (b) those in which dif-ferences are moderate-for example, wound, faeces,serology; and (c) those showing wide variation-forexample, lower respiratory, blood cultures, andmycology.An attempt has been made to explain the more

extreme differences above or below the group meanand some of the probable or possible reasons arelisted below.1 Lower respiratory tract. Laboratory C, unlike the

others, routinely examined all sputum samplesfrom new patients for the presence of acid fastbacilli. The other laboratories entered all speci-mens examined for acid fast bacilli (whether ornot specifically requested) in the category tuber-culosis.

2 Blood cultures. Some laboratories scored eachinoculated broth in a blood cQllture set as one



211A study of workload units in five microbiology laboratories

No of specimenssampled

- .._lr I

2932

Workload unitsrecorded f:::::: ,

3074 4692

51261 40 531

ai] UrinesE3 Wound and

genital

4840 6573

75475 76093

2 Respiratory a] FaecesIN Tuberculosis E Serology/

virology

W OthersU Non-clinical

Fig. 2 Specimens sampled and workload Units generated in each laboratory.

Wound Cerebrospinal Serology/Upper Genital on fluid Faeces assayrespiratory Urine ]. 4 4 4

-2 aio M r variation

Little variation Moderate variation -

Lowerrespiratory16i,

0-

-8

Mycology.D- _Blood

culture11,

0-

Eu

1'U

0l

-9.

Wide variation

Virology. Culture/Non- electronmicroscopy

gexg >s clinical;Tuberculosis ciia

0 0- Lal

-13- -14.

Fig. 3 Variation between laboratories in mean workload units per specimen. Laboratory A did not undertake mycologyand laboratory E did no virology (culture or electron microscopy).

91226

iboratories[DAOBocEDC1E



212Table 3 Ranking oflaboratories by total specimens, totalworkload units (WLUs) and WLUlspecimens

Total specimens Total WLUs Mean WLUfspecimen

A (lowest) B BB A EC C DD D CE (highest) E A

specimen while others scored all the brothsinoculated from the same blood as a singlespecimen. Laboratory D had a relatively highisolation rate from blood cultures necessitatingon average more tests for identification and anti-biotic sensitivities than the others. This wasprobably a reflection of samples from specialistunits (renal transplant and immunocompromisedpatients).

3 Mycology. Laboratory B, unlike the others, wasunique in employing a scientist with a substantialcommitment to mycology. Laboratory A did notundertake mycology.

4 Tuberculosis. Laboratory A did the preliminarywork on specimens for isolation of Mycobac-terium tuberculosis and passed all suspect cul-tures to a separate reference laboratory nearby.

5 Non-clinical. Laboratory B provided a "flightmeal" test service for a major airport.

6 Virology. Laboratory E did not offer a virus cul-ture or electron microscopy service. A higherproportion of neutralisation tests was performedby laboratory C compared with laboratories Aand D. This difference reflects a local epidemicof virus associated illness.

Table 3 lists laboratories in rank order accordingto the total number of specimens, the total workloadunits, and the mean number of workload units perspecimen. The order is closely similar for totalspecimens and total workload units but there areappreciable changes in ranking when workload unitsper specimen are considered.

Additional data collected but not presented hereincluded the following: (a) source of specimen (gen-eral practitioner, hospital inpatient, hospital out-patient); (b) the mean number of specimens perfamily doctor, per 100 deaths or discharges, per 100outpatients; (c) distribution of workload throughoutthe week.

Discussion

A realistic and accurate assessment of laboratoryworkload is necessary for effective distribution ofresources between laboratories and for goodlaboratory management. The extent to which details

Cartwright, Davies, Dulake, Hart, Morris, Wilkinsonare collected and analysed will depend on the pur-poses for which they are required and whether theinformation gained justifies the expense of collectingit. It is well recognised that counting requests aloneis a crude and often misleading measure of work-load. This is particularly the case when an attempt ismade to compare the workload in different pathol-ogy disciplines, some of which use automated tech-niques and others use predominantly manualmethods. Improvements have been attempted byweighting the requests by average test to requestratios. A more detailed but time consuming methodof assessing laboratory workload, such as the Cana-dian system, records the units of work for each testor procedure on each specimen. The Korner report3concluded that the Canadian system did not over-come the problems inherent in a weighted requestnumber count and recommended that numbers ofrequests only should be collected by healthauthorities for the Department of Health and SocialSecurity. The decision whether to gather any addi-tional information should be left to individual healthauthorities. The debate on obtaining comparativestatistics about activity and the use of resources hascontinued in Britain with the publication4 of per-formance indicators over a range of health districtfunctions.

This study using a modified Canadian workloadunit system has compared five combined publichealth and hospital microbiology laboratories. Weappreciated from the outset that the informationwould relate only to the work associated with thespecimens examined. It did not include media prep-aration and wash up, administration, research anddevelopment, internal quality control, consultationtime, or training. The measurements were all ofquantity and not quality and thus the study assessedworkload and not performance.The determination of the unit values chosen was

affected by the mechanisation of tests, on whethertests were performed individually or in batches, andon the experience of the staff. Some procedureswere given alternative unit values depending on themethods used. When the results were analysed itbecame apparent that the values assigned for certainprocedures required revision as the total workloadfor some specimen groups was not proportional tothe actual time spent on those specimens. This wasparticularly evident for urine, which comprised thegreatest number of specimens examined in eachlaboratory. Minor errors in the unit values of evensmall procedures were amplified out of proportionand thus distorted the pattern of the workload of thelaboratory. We also realised that accuracy and timetaken in recording workload could be improved bygrouping certain routine procedures. This would



A study of workload units in five microbiology laboratoriesalso permit adjustment of the group unit values to amore realistic figure. If, for example, all specimensof urine had a microscopical examination, proteinestimation, and culture, these tests recorded indi-vidually might qualify for three units but if groupedmight attract only two units.The particular problem in microbiology, unlike

other laboratory disciplines, is that the workrequired on a specimen cannot necessarily bedetermined when the specimen is received. Theresults of initial tests may determine the next seriesof tests. The information which is provided with aspecimen may also affect the tests performed. Theexamination of specimens from contacts, or forconfirming the absence of an organism after recov-ery from an infection, may be more limited than theexamination of a similar specimen when thepathogen is unknown. On the other hand, when it isknown that a patient has travelled abroad a moreextensive examination may be required. Even thefinal report on a specimen is not an accuratereflection of the work undertaken-for example, anegative result on a faeces specimen may have beenproduced only after extensive biochemical andserological testing of some non-lactose fermentingorganisms.Because an accurate estimation of workload on an

individual specimen cannot be obtained from eitherthe request or the report it is necessary to record theactual work undertaken. Logistically, it was notpossible to do this for every specimen, so a 10%sample was used in this study. This produced a sam-ple size of 3000 to 6000 specimens per laboratoryand was adequate to give an overall estimate oflaboratory workload. Detailed information onspecimen groups with only small numbers-forexample, cerebrospinal fluid-would require allspecimens in this group to be included in theanalysis. It has been suggested that the introductionof computers would enable the workload associatedwith each specimen to be measured. This would betrue only if every test undertaken was entered intothe computer. It is common practice, however, onlyto enter results and not all the steps entailed inreaching them; similarly several bacterial coloniesmay be examined but only the presence of any rec-ognised pathogen is recorded.The regular collection of workload data relies on

the cooperation of the staff. All the staff cooperatedwillingly in this study, encouraged by knowing that itwas for a limited period only. The gathering of datadid mean a great deal of extra work for them, andthe accuracy of workload measurement by thismethod over longer periods might well sufferbecause of this.The results of this study reflect the broadly similar

nature of the five collaborating laboratories. Allwere area public health laboratories receiving a simi-lar range of specimens, most of which wereexamined by similar techniques. Under these cir-cumstances the workload is related to the totalnumber of specimens received and furtherrefinements of measurement would be unlikely toyield significant additional information. Table 3shows that whether laboratories are ranked by totalspecimens received or by total workload unitsrecorded, the order is not significantly different.Only if a laboratory received a substantial propor-tion of specimens requiring examination by complextechniques would measurement of the work actuallydone reveal a higher workload. Laboratory A had ahigher proportion of virology specimens than otherlaboratories, which accounts for the fact that it hadthe highest mean workload unit to specimen ratio(Table 3), although it had the lowest number ofspecimens.We did not consider that analysis of workload

units by source of specimen or by deaths, discharges,or outpatient attendances would yield any more use-ful information than was obtainable by counts ofspecimens. Although an analysis of the distributionof work throughout the week is not recorded here, itwas apparent that different and misleading informa-tion could be obtained depending on whether thework was related to the day the specimen wasreceived, the day most of the bench work was done,or the day the result was issued. This is in sharpcontrast to the situation in biochemical andhaematological laboratories, where the workloadpattern can be clearly seen because the tests areusually completed and reports issued on the dayspecimens are received. The need to incubate cul-tures for 18 h or longer means that estimates of thework undertaken on different days will differdepending on the recording days used. This needs tobe taken into account if the information is to beused-for example, to assess staffing requirementsfor weekend work.What then is the value of using workload units if

they do not immediately answer all managerial andadministrative questions? One possible use is tocompare the amount of work different laboratoriesdevote to the examination of a particular type ofspecimen. Although most of the wide variationsidentified in this study resulted from a failure todefine terms sufficiently accurately, they did showsome real differences in practice. Another potentialuse is to obtain a quantitative estimate of the benchtime taken in an examination by manual methods toassess the likely advantage of automation. Althoughother considerations such as capital and revenuecosts and speed and accuracy of reporting results

213



214

would be included in such an assessment, it is impor-tant to estimate what manpower resources might beliberated.The PHLS has not continued with collecting

workload data but uses specimen counts on oneselected day every month. The specimens aredivided by type and source. This study indicates thatthe impact of any important changes could beexamined by measuring the workload entailed.

It must be clearly understood by all who use orwish to use workload units that they measure thework actually done, not what should be done. Quan-tity and quality are not synonymous. It may be mis-leading to assume that a laboratory which shows alow workload unit per specimen ratio is managed ina more efficient, selective, or cost effective way. Itmay simply be that such a laboratory is under-resourced to the extent that it is forced to provide asuboptimal service.

We are grateful to the South Western RegionalHealth Authority for making the results of their pre-liminary study available to us. Dr GT Mills and MrAD Kilburn generously shared their expertise and

Cartwright, Davies, Dulake, Hart, Morris, Wilkinson

experience with us and gave invaluable advice. Ourhead medical laboratory scientific officers, Messrs JPAlexander, GF Down, TA Ford, R Human, DAPorter, and Dr RA Bassett played important parts inorganising the trial.

References

Morris CA. Trends in microbiology work-loads in the NationalHealth Service: England and Wales (1968-79). Health Trends1981; 13:8.

Statistics Canada. Canadian schedule of unit values for clinicallaboratory procedures. Ottawa: Statistics Canada, Health Divi-sion, 1978.

National Health Service/Department of Health and Social Sec-urity. Steering Group on Health Services Information. Areport on the collection and use of information about hospitalclinical activity in the National Health Service (Chairman Mrs EKorner). London: HMSO, 1982.

4 Department of Health and Social Security. Health services man-agement performance indicators. London: DHSS, 1983.(DHSS Health Notice (83) 25).

Requests for reprints to: Dr RJC Hart, Public HealthLaboratory, Church Lane, Heavitree, Exeter EX2 5AD,England.



microbiology laboratories.A study of workload units in five

Morris and P J WilkinsonR Y Cartwright, J R Davies, C Dulake, R J Hart, C A

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