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CLIN. CHEM. 21/1, 87-92 (1975)
R1
j’.-! I
Evaluation of Discrepancies in Patients’ Results-
An Aspect of Computer-Assisted Quality Control
Philip Whitehurst,1 Thomas V. Di Silvio,2 and Gaydzag Boyadjian1
A computer program has been devised to select those It has been advocated that error detection routines
clinical chemistry results that have a high probability of be included in clinical laboratory computer systems
error for inclusion on a discrepancy report, which is (1-5), and estimated that computer-assisted error
printed on demand throughout the day. Each report detection could result in a savings of $3500-$5000
entry is evaluated by a supervisor, who decides whether yearly in technologist and physician time in a 350-
to accept the result or to re-assay. With this program, bed hospital (2). General recommendations for such
8.4% of all results were included on the report, 1.9%
programs have been published (1, 5), as has a de-
were re-assayed, and 0.83% were judged to be in error
and corrected. Checking results at the time of their re- scription of an algorithm for checking SMA 12 nor-
lease to the computer has led to earlier report delivery mal-abnormal patterns (3).
and more convenient timing of re-assays without com- Our program was devised with the main objective
promise of patient safety. of detecting potential discrepancies in results on pa-
tients soon after analysis, so that re-assay and needed
AddItIonal Keyphrases: screening of data on patients correction could be performed in most cases before
report printout. Additional objectives were to alert
After implementation of a laboratory computer laboratory supervisory personnel to the presence of
system in the clinical chemistry section of our labora- extremely ill patients, and to provide a means for
tory, it became possible to enhance quality control by finding patients for special projects from time to
visual report checking. As the numerous separate re- time.
ports formerly issued on a single patient had now
been collated into three daily nursing-unit reports Method
followed by a cumulative six-day summary report Hardware
each evening, convenient formats were available for
The present system consists of an IBM S/1800-S/7
comparing results on patients, and discrepancies
combination (IBM Corp., White Plains, N. Y. 10604).
were found that would have previously escaped no-
The S/7 acquires data on-line from an SMA 6, an
tice.
SMA 12 (Technicon Instruments Corp., Tarrytown,
However, there were several obvious drawbacks to
N. Y. 10591), seven channels of AutoAnalyzers, and a
the visual checking system. First, the amount of time
Model S hematological system (Coulter Electronics,
required to check more than 2900 results daily led to
Inc., Hialeah, Fla. 33014). Test requests and input
a delay in report delivery. Second, discrepancies went
from off-line instruments are performed via cathode
unnoticed by even the most experienced, well-moti-
ray tube displays and keyboards (Trivex, Inc., Costa
vated observers. Third, most discrepancies were
Mesa, Calif. 92627), as are most routine system func-
found after the afternoon report printout. As a con-
tions. The system also utilizes four IBM 2311 disc
sequence, the re-assays created a burden for evening
drives, two high-speed line printers (350 and 600
personnel, and, in some instances, had to be deferred
lines per minute), and various data and error loggers.
until the following day, with resulting danger to the
patient and inconvenience to the attending staff. Software
The basic system software is the IBM Clinical Lab-
Management Services, Thomas Jefferson University, Philadel-
oratory Management System (CLMS) and Multi-
phia, Pa. 19107.
2 Clinical Laboratories, Thomas Jefferson University Hospital,
and Department of Pathology, Jefferson Medical College of Thom-
as Jefferson University, Philadelphia, Pa. 19107. Nonstandard abbreviations used: SMA and AA, Sequential
Received July 31, 1974; accepted Oct. 17, 1974. Multiple Analyzer and AutoAnalyzer (Technicon Corp.).
CLINICAL CHEMISTRY, Vol. 21, No.1, 1975 87
Programming Executive (MPX), the former having plier and an allowed range of deviation. For instance,
been extensively modified. The basic S/7 software if an SMA 12 result for lactate dehydrogenase (upper
consist of an IBM field-developed assembler lan- limit of normal, 225 U/liter) is to be compared to a
guage program, also extensively modified. kinetic result for lactate dehydrogenase on the same
The program that is the subject of this publication specimen (upper limit of normal, 90 U/liter), the
was written by one of us (G.B.) in Fortran IV com- SMA 12 value is multiplied by 0.4. This converted re-
puter language. Limits for the various checks are con- sult must agree with the kinetic result within 15 U!
tained in a single file, and can be changed readily via liter. If the units for the methods being compared are
punched-card input. A second file, the discrepancy directly comparable (for example, if an SMA 12 albu-
file, contains the pertinent information on those re- min result is being compared with an albumin value
sults that have failed a check. obtained by electrophoresis), a multiplier of 1.0 is
used.
Program Concepts The previous value check is used to compare a re-
It is obviously impossible for either a laboratory sult with the previous result for the same test on the
supervisor or a computer to assess the validity of a most recent previous specimen, within four days. For
single isolated laboratory result. Thus, individuals instance, serum protein results differing by more
who evaluate laboratory results (in the absence of than 1.5 g/dl from a previous value will be written
knowledge of the patient’s clinical problems) will or- into the discrepancy file. For some tests, the previous
dinarily attempt to compare a result with results of value check is more complex. For instance, if the
related tests performed on the same specimen and limit of 1.5 g/dl is accepted as the maximal allowable
with results of the same test performed on prior spec- day-to-day change in serum protein concentration,
imens. If the result cannot be compared to other re- this limit seems as valid for a patient with a serum
sults, it may still be questioned if it is at an extreme protein concentration of 4.0 g/dl as for a patient with
of the range of the total patient population. The ex- a serum protein concentration of 9.0/dl. However, a
perience and knowledge of the individual checking patient whose serum urea nitrogen is 75 mg/dl would
will be brought to bear on the decision as to the va- be expected to change more from day-to-day than
lid ity of the result. one with a concentration of 15 mg/dl. Therefore, for
This program has been designed to select those re- some tests, the limits file contains three entries for
sults most likely to be in error, and present them in previous value checks: the allowable low-range
an organized format to the supervisor for further ac- change (in absolute units), the allowable high-range
tion. The program provides four types of checks, des- change (in percent), and the point of division be-
ignated as arithmetic, discordance, previous value, tween high and low range. For example, if a given
and alert. For each check, we set limits (Table 1). No urea nitrogen concentration is less than 25 mg/dl, it
attempt was made to establish these limits by rigor- will be written to the discrepancy file if it differs
ous statistical means; rather, the limits were set from the preceding value by more than 5 mg/dl.
subjectively by the clinical chemistry section head, However, if a given urea nitrogen concentration is 25
and were based on known intralaboratory analytical mg/dl or above, it will be written to the discrepancy
variance and his clinical experience. file only if it differs from the preceding result by
The arithmetic check is used to compare more more than 20% of the result being checked.
than two results from the same specimen that have a For most tests, the previous value check limits
demonstrable mathematical relationship. At present have been set to be rather narrow, on the basis of an-
it is used for “balancing” electrolytes and for check- ticipated change in 24 h, even though this check is
ing acid-base calculations. For balancing electrolytes, made on results obtained as much as four days pre-
a term “DELTA” is defined as viously. Setting such narrow limits allows the labora-
tory supervisor to exercise his judgment to determine
DELTA = [K] + [Na] - [HC03] - [Cl-I (1) whether or not re-assay is truly needed, based on the
time interval or other knowledge he may have about
DELTA values of less than 10.0 mmol/liter or greater the patient. Although many valid values are thus
called to the supervisor’s attention, the risk of miss-
than 21.0 mmol/liter are written into the discrepancy
ing a true change is lessened.
file for eventual printout. For checking acid-base cal-
The alert check is designed to find very large ana-
culation, actual bicarbonate and total CO2 are calcu-
lated from pH and p co2 by means of the Henderson- lytical, entry, or transcription errors, to alert labora-
Hasselbalch equation, and the calculated values are tory supervisors to very ill patients, or to find pa-
tients of special interest. For instance, a urea nitro-
compared to the values entered by the technologist.
Differences of more than 2.0 mmol/liter are written gen of less than 3 mg/dl or greater than 50 mg/dl is
into the discrepancy file.
written into the discrepancy file.
The discordance check is used to compare two re-
Program Operation
sults from the same specimen that have a defined
mathematical relationship. For the discordance After verifying test results for a given worklist via
check, the limits file contains two entries, a multi- the screen of the cathode ray tube, and printing a
88 CLINICALCHEMISTRY,VoI.21, No.1,1975
Table 1. Limits for Discordance, Previous Value, and Alert Checksa
Previous value limits
Discordance check limits - Alert limits
Low Division High
Test Tested against Multiplier Range range point range Lower Upper
Glucose, SMA65 Glucose, SMA12 1.0 ±10 ±100 300 ±50% 50 500
Glucose, SMA12b Glucose, SMA6 1.0 ±10 ±100 300 ±50% 50 500
Urea nitrogenb Creatinine, AAI 13.0 ±10 ±5 25 ±20% 3 50
Creatinine, SMA12 13.0 ±10
Creatinine, AAIb Creatinine, SMA12 1.0 ±0.3 ±0.5 2 ±25% 0.3 7.5
Urea nitrogen 0.07 ±1.0
Creatinine, SMA12b Creatinine, AAI 1.0 ±0.3 ±0.5 2 ±25% 0.3 7.5
Urea nitrogen 0.07 ±1.0
Uric acid, AAP Uric acid, SMA12 1.0 ±1.0 ±1.5 8.0 ±25% 1.0 12.0
Uric acid, SMA12b Uric acid, AAI 1.0 ±1.0 ±1.5 8.0 ±25% 1.0 12.0
Albumin, electrophoresisc Albumin, SMA12 1.0 ±0.6 ±1.5 N/A ±1.5 1.5 6.0
Albumin, SMA12C Albumin, electroph. 1.0 ±0.6 ±1.5 N/A ±1.5 1.5 6.0
Protein, manual” Protein, SMA12 1.0 ±0.8 ±1.5 N/A ±1.5 4.0 9.0
Protein, SMA12” Protein, manual 1.0 ±0.8 ±1.5 N/A ±1.5 4.0 9.0
Sodium4 N/At N/A N/A ±6 N/A ±6 120 150
Potassium4 N/A N/A N/A ±1.2 N/A ±1.2 3.0 6.0
Chlorides4 N/A N/A N/A ±8 N/A ±8 85 115
CO2 content,SMA6d CO2 content,calc. 1.0 ±4.0 ±6 N/A ±6 10 40
Osmolality, serume N/A N/A N/A ±15 N/A ±15 265 320
Osmolality, urinea N/A N/A N/A N/A N/A N/A 150 1200
Calcium, AASb Calcium, SMA12 1.0 ±1.0 ±1.5 N/A ±1.5 6.5 13.0
Calcium, SMA12b Calcium, AAS 1.0 ±1.0 ±1.5 N/A ±1.5 6.5 13.0
Phosphorus, AAI5 Phosphorus, SMA12 1.0 ±1.0 ±2.0 N/A ±2.0 1.0 8.0
Phosphorus, SMA12b Phosphorus, AAI 1.0 ±1.0 ±2.0 N/A ±2.0 1.0 8.0
Iron’ N/A N/A N/A ±12 100 ±20% 20 250
Iron-binding cap.’ N/A N/A N/A ±50 350 ±20% 200 600
Cholesterol, AAl’ Cholesterol, SMA12 1.0 ±40 ±50 300 ±30% 100 500
Cholesterol, SMA125 Cholesterol, AAI 1.0 ±40 ±50 300 ±30% 100 500
Triglyceridesb N/A N/A N/A ±30 250 ±25% 40 1000
Bilirubin, AAIb Bilirubin, SMA12 1.0 ±0.4 ±1.0 3.0 ±50% 0.2 10.0
Bilirubin, for newborn 1.0 ±1.0
Bilirubin, SMA12t Bilirubin, AAI 1.0 ±0.4 ±1.0 3.0 ±50% 0.2 10.0
Bilirubin, for newbornb Bilirubin, AAI 1.0 ±1.0 ±2.5 10.0 ±25% 1.0 15.0
Lactate dehydr., Lactate dehydr., 2.5 ±40 ±50 250 ±50% 50 600
kinetic
Lactate dehydr., kinetics Lactate dehydr., 0.4 ±25 ±25 150 ±40% 10 1000
SMA12
Alk phosphatase, SMA125 Alk phosphatase, 2.4 ±20 ±50 125 ±50% 10 300
phenolphthalein
monophosphate
Alk.phosphatase,#{176} Alk.phosphatase, 0.42 ±9 ±15 60 ±30% 5 250
phenolphthalein SMA12
monophosp hate
Asp. aminotrans., Asp. aminotrans., 1.8 ±20 ±25 75 ±50% 5 300
kinetic
Asp. aminotrans., Asp. aminotrans., 0.55 ±10 ±20 100 ±40% 2 750
kinetics SMA12
Ala. aminotrans. N/A N/A N/A ±20 100 ±40% 2 750
Acid phosphatase#{176} N/A N/A N/A ±2.0 10.0 ±25% 0.1 10.0
Amylase N/A N/A N/A ±100 500 ±25% 20 1000
Creatine kinase5 N/A N/A N/A ±50 250 ±40% 5 1500
Acid-base group
pH N/A N/A N/A N/A N/A N/A 7.10 7.65
N/A N/A N/A N/A N/A N/A 40 135
pcop N/A N/A N/A N/A N/A N/A 10 80
Actual bicarb.4 N/A N/A N/A ±8 N/A ±8 9 39
CO, content, calc.” CO, content, SMA6 1.0 ±40 ±9 N/A ±9 10 40
Base excess4 N/A N/A N/A ±6.0 N/A ±6.0 -12.0 +12.0
Standard bicarb.4 N/A N/A N/A ±8 N/A -8 10 40
“Arithmetic check limits are contained in text. For discordance check, multiplier acts on result being tested, and prod uct is compared
with result listed as “tested against,” applying respective range. For previous value check, respective low range or high range limits
will be selected depending on relation of result being tested to division point. For alert check, values below respective low or above re-
spective upper limits fail check.
mg/dl; g/dl; “mmol/liter; ‘mosm/kg; fg/dl; U/liter; h mm Hg; N/A, not applicable.
‘.,
Table 2. Classification of Discrepancy File Entries
(Representative 12-day Period)
Percent
Percent of die-
of total crepancy
test file
results #{149}ntrl.s
Total test results 30870
Total discrepancy file entries 2579 8.35
Total errors found and 255 0.93 9.9
corrected (*)
Arithmetic check failures 580 1.9 22.5
Electrolytes, judged correct
Electrolytes, insufficient 132 0.4 5.1
quantity to reassay
Electrolytes correct by 335 1.1 13.0
reassay
5Electrolytes in error by 147 0.5 5.7
reassay
Acid-base calculations 28 0.1 1.1
judged correct
5Acidbase calculations in 32 0.1 1.2
error
Discordance check failures
Judged correct 320 1.0 12.4
Not enough to repeat 16 0.1 0.6
*Error found by reassay 53 0.2 2.1
Previous result check failure Fig. 1. Outline of program logic (Y = Yes, N = No). The
Judged correct 434 1.4 16.8 checking algorithm is automatically initiated immediately after
Correct by reassay 4 0.1 0.2 the technologist has visually reviewed the data on a CR1, and
5Error found by reassay 9 0.1 0.3 indicated approval
Alert check failures
Judged correct 438 1.4 17.0
*Error found by reassay 5 0.1 0.2
5Entry errors 9 0.1 0.3 tient; the result; the type of check that has been
Judgment not recorded 37 0.1 1.4 failed; and the test code, date, time, and specimen
number associated with that result. If electrolytes
have not balanced, the DELTA value is also printed,
together with the associated glucose and urea nitro-
gen values. In many instances, this allows rapid ex-
hard copy of those results, the technologist releases planation of elevated DELTA values. For failures of
the results into the master log file (Clinical Laborato- any check except discordance, the most recent previ-
ry Management System, IBM). It is at that time that ous result for that test (within four days) will appear.
the discrepancy checks are automatically performed. In case of discordance check failure, the discordant
Results are released into the master log file, whether result appears, similarly identified. Ample spacing
or not they have been written into the discrepancy between lines of the report allows it to be used as a
file, and are then available for reports or inquiry. log of action taken for each report entry.
In addition to the limits already discussed, the lim- Once the report has been printed, the laboratory
its file contains a group of bits to identify which supervisor evaluates each entry. In many cases one
checks are to be performed on a given result. The can decide immediately, from the information on the
checks are performed in the order: arithmetic, dis- report itself, whether or not to re-assay. In other
cordance, previous value, alert (Figure 1). This order cases, before making a decision, the supervisor may
allows checks making the greatest number of com- need to refer to other results for the patient. These
parisons to be performed first. If a result fails a are easily accessible via cathode ray tube screen. Fre-
check, subsequent checks are not performed and quently, clinical information is obtained from the pa-
computer time is saved. tient’s chart by the clinical pathologist or resident, or
Results failing any check are written into the dis- the attending physician may be consulted.
crepancy file. At frequent intervals during the day, After a re-assay, the supervisor will update the
laboratory supervisors call for a discrepancy report, master log file containing the result. If re-assay has
which prints out the contents of the discrepancy file shown the original result to be correct, a two-digit
(as exemplified in Figure 2). This report contains the code will be-entered by the supervisor via cathode ray
name, identification number, and location of the pa- tube, causing the abbreviation “CKD” (for
90 CLINICALCHEMISTRY,Vol.21, No.1,1975
PRINTEO 06/20/74
THOMAS JEFFERSON UNIVERSITY HOSPITAL XXX-XXXX-XXX
TIMF 1753 HRS CLINICAL LABORATORIES
DISCREPANCY REPORT PAGF S
(.UMPL F T F CHEMI STRY
- CURRENT RELEASED RESULTS FAILING INDICATED CHECK COMPARISON RESULTS OTHER INFORMATION
CHECK itO CTC X-NUMBER SPEC NO LOCAT AGE SEX TIME RESULT RESULT lCD CTC DATE TIME PATIENT NAME
PREy CPK CPK 0714618 0620366 451H 48Y N 1039 2030 1624 CPK CPK 0619 0825 ROBERT J
0Y M 0900 820 93 CPK CPK 0619 0900 CARNAN
PREy CPK CPK 0708339 0620015 551C
915CR RUN SN6 0052704 0620097 USiA bOY M 0900 49 1.7 CRT CR1 0620 0900 JOSFPH
AR ITH CL SM6 0054270 0620170 N6488 85Y N 0900 106 JACOB
AR I TN C02 0900 29
AR ITH K 0900 3.8
ARIIH NA 0900 141
AR ITH BuN 0900 34
API IN GLF 0900 181
DEL TA 9.7
ALERT CL SM6 0054205 0620071 1057* 49Y F 0900 83 AL ICE 0
PREy NA SM6 0053298 0620030 811A Sly F 0900 143 136 NA SM6 0619 1122 t ELOISE
PREy BUN SM6 0053199 0620038 8258 21Y F 0900 58 76 BUN SM6 0619 0900 PAuLETT
PREy BUN SM6 0703199 0620150 M222A 34Y N 0900 20 14 BUN SM6 0618 0900 JAMES
0!SCR CRT SMA 0712034 0620339 11578 385’ N 0900 10.4 57 BUN SN6 0620 0900 REV RALP
ALERT ALP 0900 354
AL FRI GOT .. 0900 335
015CR CLF SMA 0051292 0620010 5518 64Y F 342 359 GLU 5Mb 0620 0900
UISCR CRT 0700 5.3 88 BUN 5Mb 0620 0900
PREy LDH 0700 524 606 lOU SNA 0619 0915
PREy GOT 0715 33 64 GOT SMA 0619 0915
ALERT PHD 0715 8.7 6.9 PHI) SNA 0619 0915
ALERT IIRC 0715 12.1 11.5 URC SMA 0619 0915
r)ISCR CR1 SMA 0052670 0620126 0*248 69Y F 1.0 .7 CR1 CR1 0620 0900 LILY 0
ALFRT ALP 0700 339
015CR CRT SMA 0706457 0620133 0*54* 41Y F 3.4 3.1 CRT CRT 0620 0900 JACKSON
015CR PRO SNA 0054239 0620134 0*56* 79Y F 5.5 6.5 T P PEL 0620 JULIA N
015CR CR1 SMA 0243188 0620092 11518 67Y N 1.2 30 BUN SM6 0620 0900 #{149} LOUIS
015CR C,LF SNA 0054262 0620165 M633R 37Y F 117 106 GLU 5Mb 0620 0900 DORIS
I)ISCR CR1 SMA 0054205 0620071 1057* 49Y F 1.2 29 RUN SN6 0620 0900 ALICE 0
Fig. 2. Example of discrepancy report
“checked”) to appear with the result on all subse- sis and cardiac patients comprise a large segment of
quent reports. If an error has been found, entry of a our patient population. As expected, patients with
different two-digit code will cause the abbreviation renal failure, diabetic acidosis, cardiac failure, and
“LAB COR” (for “laboratory correction”) to appear anoxia accounted for most high DELTA values.
with the result. If the erroneous result has already Many of the patients with low DELTA values were
appeared on a report, the nursing unit is additionally hypoproteinemic or on intravenous hydration. Errors
notified by telephone. in sodium and chloride were about equal in number.
An alternative approach to the arithmetic check
Results would have been to calculate the DELTA for each
The results from 12 consecutive days in May 1974, specimen as soon as it had been analyzed by the SMA
have been tabulated (Table 2). A total of 255 errors 6. That approach would have given the advantage of
were found and corrected, a rate of 0.83%. If the spec- immediate checking. However, by delaying the check
imens judged in need of re-assay, but not available in for a few minutes, as in our system, the responsibility
sufficient quantity for the re-assay, had an error rate for a decision not to re-analyze is placed with the su-
comparable to that for those that were re-assayed, pervisor, rather than the operator. Throughput is not
there would have been an estimated 329 errors, or adversely affected, since the specimen would be re-
1.07% of all the results. analyzed at the end of the worklist in either case.
Most of the discordance check failures judged by a
Discussion supervisor to be correct were creatinine-urea nitro-
Most of the discrepancies were found by the arith- gen discrepancies in patients who were on dialysis,
metic check of electrolytes, not surprising, since pregnant patients, and patients with liver disease or
about 25% of all the assays performed in the clinical pre-renal azotemia. Next most common were differ-
chemistry section are for electrolytes and since dialy- ences for cholesterol as measured by the direct SMA
CLINICAL CHEMISTRY, Vol. 21, No.1,1975 91
12 method and the AutoAnalyzer I (isopropanol-ex- consistent in the subjective clinical judgment of the
tracted) method in patients with bilirubinemia or tn- examiner.
glyceridemia. The discordance errors substantiated Because of these residual apparent errors, one can-
by re-assay were usually glucose assays performed on not omit visual checking of reports. However, the vi-
both the SMA 6 and SMA 12. sual check does not now interfere with report deliv-
At first glance, it would appear that very few previ- ery or laboratory operation. The nursing unit reports,
ous result-check failures were re-assayed. In our sys- printed at 5:00 a.m., 1:00 p.m., and 4:00 p.m. are no
tem, previous results are made available on worklists, longer checked visually, because no correlations
and in most cases re-assays will have been initiated could be made visually that have not already been
and completed by the bench technologist. Thus, the checked by the program. Because of the very low
previous result check serves only as a double check yield of additional errors, the summary reports are
here. not checked before delivery; however, the laboratory
The alert check is also expected to yield only a low copy of these reports is being checked by the evening
return of errors, because the main function of this supervisor in chemistry while the report is being de-
check is to discover very large entry errors. It will also livered, saving nearly an hour in delivery time. This
alert the supervisors to very ill patients. copy is then routed to the head of the clinical chemis-
Although for the program under discussion, limits try section, who rechecks it early the next day. Be-
were set subjectively, the program can use limits set cause the routine checking has been done, the visual
by any method, as these limits are contained in an checkers can apply their expertise to discovering re-
easily accessible file. It is possible that limits set by lationships among results that are inconsistent with
sophisticated statistical techniques and then opti- their clinical judgment.
mized could reduce the number of results selected for The program described has made it possible to dis-
visual checking. We have elected instead to use the cover many errors that otherwise would have been
more direct, but admittedly subjective approach, in missed. It has benefited the operation of the labora-
the interest of a more immediate solution to the tory, allowing errors to be found with minimal effort,
problem of checking a truly overwhelming number of at a time convenient for re-assay. In this manner, dis-
results. ruption of laboratory routine and salary costs for
While it
is quite easy to document the number of overtime are avoided. Most important, errors are de-
errors found and corrected by re-assay, an accurate tected and corrected before a clinical decision can be
count of the errors missed by the program is impossi- made that might be deleterious to the patient. We
ble. Published estimates of laboratory error rates are conclude that this program is an effective use of the
understandably uncommon (6, 7). We attempted to computer in laboratory quality control.
approach this problem by making an admittedly sub-
jective survey of in-patient six-day summary reports References
during the same 12-day period. These reports were
checked by one of us (T.V.D.) for residual apparent 1. Council of the Association of Clinical Pathologists, Data Pro’
errors. Fifty-eight possible errors were found (0.2%). cessing in Clinical Pathology. J. Clin. Pathol. 21, 299 (1968).
2. Krieg, A. F., Johnson, T. J., McDonald, C., and Cotlove, E.,
Of these, 28 represented electrolytes (seven sets) the Clinical Laborator Computerization. University Park Press, Bal-
DELTA of which had been questioned by the pro- timore, Md., 1971, pp 86-87.
gram, but which had not been re-assayed, either be- 3. Poletti, I. J., Zack, J. F., and Mueller, T. J., Computer control in
cause of lack of sample or of a supervisor’s decision. the clinical laboratory. Amer. J. Clin. Pathol 53, 731 (1970).
4. Walter, A. R., What to look for in a computerized laboratory in-
The remaining 30 had not been detected by the pro-
formation system, Part I. Lab. Med. 3/1, 32 (Dec. 1972).
gram. Thirteen involved discordances on different 5. Walter, A. R., What to look for in a computerized laboratory in-
days, such as total protein by SMA 12 of 8.0 g/dl, fol- formation system, Part 11. Lab. Med. 4/1, 32 (Jan. 1973).
lowed a day later by a manually-obtained total pro- 6. Reed, A. H., and Henry, R. J., Accuracy, precision and control
tein value of 5.6 g/dl. Ten represented irregularities charts. In Clinical Chemistry, Principles and Techniques, 2nd
ed., R. J. Henry, D. C. Cannon, and J. W. Winkelman, Eds. Harper
in trends, without enough day-to-day change to have & Row, Hagerstown, Md., 1974, p 298.
exceeded the previous value limits. The remaining 7. McSwiney, R. P., and Woodrow, D. A., Types of error within a
seven were multitest patterns that appeared to be in- clinical laboratory. J. Med. Lab. Technol. 26, 340 (1969).
92 CLINICALCHEMISTRY, Vol. 21, No. 1. 1975
