Full text of DOI:10.1111/j.1553-2712.2000.tb00481.x

ACADEMIC EMERGENCY MEDICINE • November 2000, Volume 7, Number 11
1311
The Benefit of Houseofficer Education on Proper
Medication Dose Calculation and Ordering
L
EWIS S. NELSON, MD, PETER E. GORDON, MD, MARC D. SIMMONS, MD,
ILLIAM L. GOLDBERG, MD, MARY NN OWLAND, PHARMD,
OBERT S. HOFFMAN, MD
W
A
H
R
Abstract. Objectives: Drug dosing errors com- did not take T1, in order to determine test equiva-
monly cause morbidity and mortality. This prospec- lency (T1 vs T2). Tests were graded using explicit cri-
tive controlled study was performed to determine: 1) teria by a single investigator blinded to the order of
residents’ understanding of drug dose calculations administration. Results: Twenty residents completed
and ordering; and 2) the short-term effect of a brief both tests T1 and T2a. Their mean scores were 48%
educational intervention on the skills required to and 70%, respectively (p < 0.001, paired t-test). The
properly calculate dosages and order medications. control group of ten residents had a mean score of
Methods: The study was conducted at an urban pub- 49% (T2b), similar to the study group’s scores on T1
lic hospital with a four-year emergency medicine (T1 vs T2b, p = 0.40, unpaired t-test). Conclusion:
(
EM) residency program. The EM residents served as Emergency medicine residents require specific train-
the study group and were unaware of the study de- ing in calculating and executing drug ordering. A
sign. A written, eight-question test (T1) with clinical brief educational intervention significantly improved
situations and factual questions was administered. short-term performance when retested six weeks
Immediately following the test, correct answers were later. Long-term retention is unknown. Key words:
discussed for 30 minutes. Key concepts were empha- medical errors; medication errors; prescriptions,
sized. Six weeks later, a repeat test (T2a) with a sim- drug; education, medical; internship and residency.
ilar format was administered to the study group. The ACADEMIC EMERGENCY MEDICINE 2000; 7:
same test (T2b) was simultaneously administered to 1311–1316
a control group, residents of similar training who
1
HE INSTITUTE of Medicine (IOM) report, confusion between drugs with similar names to in-
released in 1999, implicates medication er- correct patient identification.
T
rors as the direct cause of at least 7,000 patient
However, one of the leading causes of iatrogenic
deaths annually. These numbers are supported by medical injury is incorrect drug calculations and
3
the Harvard Medical Practice Study, published in ordering. This type of error is implicated in up to
4
1
991, which identified that nearly 4% of all pa- 15% of all errors in medication ordering. The prob-
tients admitted to hospitals in New York State suf- lem is particularly prevalent in the practice of pe-
2
fered a consequential iatrogenic injury. The ap- diatrics, where weight-based calculations are
5
parently simple act of administering a medication needed for virtually every prescription. Moreover,
is actually the culmination of numerous sequential since children account for approximately 15% of
steps, each with its own potential for error. Thus emergency department (ED) visits, the impact of
the causes of medication errors are diverse and drug dosing errors in emergency medical practice
span the spectrum from incorrect drug ordering to is obvious.
Little formal education in dose calculations and
order writing is typically offered in medical school
or during residency. The assumption is that phy-
From the Department of Emergency Medicine, Bellevue Hos- sicians learn this skill independently. Conven-
pital Center/New York University School of Medicine, New
York, NY (LSN; PEG; MDS; WLG; RSH); the New York City
Poison Control Center, New York, NY (LSN; MAH; RSH); and
St. John’s University College of Pharmacy and Allied Health
tional medical education focuses on specific disease
entities, likely to affect only a fraction of the pa-
tients for whom clinical care is rendered. Con-
versely, medication ordering affects virtually every
Professions, Queens, NY (MAH).
Received May 30, 2000; revision received July 7, 2000; ac- patient by often imperceptible or delayed means.
cepted July 19, 2000. Presented at the SAEM annual meeting,
San Francisco, CA, May 2000.
Address for correspondence and reprints: Lewis S. Nelson, MD,
Given the large and increasing volume of patients
passing through EDs nationally, even a trivial er-
ror rate may result in thousands of iatrogenic ad-
verse events.
4
55 First Avenue, Room 123, New York, NY 10016.
Fax: 212-447-8223; e-mail: lnelson@pol.net

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DOSING EDUCATION
Nelson et al. • BENEFIT OF EDUCATION ON MEDICATION DOSING
Figure 1. Test questionnaire 1 (T1).
This study was designed to evaluate the base- tional review board and informed consent was ob-
line ability of emergency medicine (EM) residents tained from each participant prior to each
to properly calculate and write orders for medica- examination.
tions with complex dosage calculations. This is
only one part of the entire process of medication
delivery, but one that is amenable to correction
through education. We hypothesized that a brief,
focused educational effort directly aimed at im-
proving residents’ abilities to properly dose and or-
der medications would have a measurable benefit
when the residents were re-evaluated six weeks
later.
Study Setting and Population. All EM resi-
dents attending a weekly educational conference at
a four-year (PGY 1–4) EM training program par-
ticipated in this study. Conference attendance is
mandatory for all EM residents currently assigned
to the ED.
Study Protocol. A test questionnaire (T1) con-
sisting of eight questions involving case scenarios
was distributed to residents at a weekly confer-
ence. The case scenarios consisted of typical clini-
METHODS
Study Design. This was a prospective study as- cal situations in which a standard drug must be
sessing the baseline ability of EM residents to cal- administered in a defined dose (Fig. 1). The study
culate and prescribe complex medication orders. subjects were asked to calculate the appropriate
Additionally, the effect a brief educational effort dose with the given information and/or write an
had on the performance of these skills was as- order for that drug. Additional factual questions
sessed. This study was approved by the institu- regarding drug dosages and concentrations were

ACADEMIC EMERGENCY MEDICINE • November 2000, Volume 7, Number 11
1313
included as well. All participants, regardless of
Six weeks later, a repeat test (T2a, Fig. 2) was
their background, were asked to complete all of the administered to the same group that had previ-
questions, since the skills necessary to write a ously completed T1. At the same time, this test
medication order are implicit in the duties of all (T2b) was administered to a control group of EM
participants. Ten minutes was allowed to answer residents who had not been present six weeks ear-
the eight questions.
lier, had not taken T1, and had not received the
Immediately after the questionnaire, the cor- brief educational intervention. The format of test
rect responses were discussed in an educational T2 was similar to that of T1; only the drugs and
session with the group for about 30 minutes, and dose calculations were altered. In order to limit
all questions posed by the residents were an- bias, the study subjects did not know of the study
swered. In addition, during the educational session ahead of time. Also, there was no suggestion that
certain key concepts, including the epidemiology of retesting would occur in order to eliminate addi-
iatrogenic drug toxicity, were emphasized.
tional preparation by the study group or advanced
Figure 2. Test Questionnaire 2 (T2a and T2b).

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DOSING EDUCATION
Nelson et al. • BENEFIT OF EDUCATION ON MEDICATION DOSING
Figure 3. Trend in the scores of individual residents from T1 to T2a.
notice of testing for the controls. Entry into the (Ϯ standard deviation) of this group for test T1 was
control or study group was based on attendance at 48% (Ϯ23) and for T2a was 70% (Ϯ18) (p < 0.001,
the conference; no other criteria were used.
paired t-test). Eighty percent (16/20) of the study
group obtained higher scores on the repeat test
(
T2a, Fig. 3). The control group contained ten res-
Measurements. The tests (T1, T2a, and T2b)
were graded using explicit predetermined criteria
by a single independent investigator (PEG) blinded
to the order of test administration and the identi-
ties (names and subject vs control status) of the
residents. If appropriate, partial credit was
awarded for incorrect answers if the correct con-
ceptual process was documented on the examina-
tion sheet. Certain questions did not accommodate
the assignment of partial credit, such as those
where one best answer was to be identified from a
list of choices.
idents who completed test T2b only. The mean
score on this test was 49% (Ϯ19), which was sim-
ilar to the study group scores on T1 (T1 vs T2b, p
=
0.40, unpaired t-test).
The study group included more senior-level res-
idents (PGY 3 and 4) than the control group (p =
.03). The mean scores on T1 were 60%, 57%, 39%,
0
and 53% for PGY 1, 2, 3, and 4 residents, respec-
tively. The mean scores on T2b were 66%, 51%, and
3
There were no PGY 4 residents in the control
group.
9% for PGY 1, 2, and 3 residents, respectively.
Data Analysis. All participant information was
entered into a Microsoft Excel 7.0 database (Red-
mond, WA). Distributions of the training levels
among the study and control groups were com-
pared using a two-tailed chi-square test. A two-
tailed paired t-test was used to compare study par-
ticipants’ performances on tests T1 and T2a. A
two-tailed unpaired t-test was used to compare the
study group’s performance on test T1 with the con-
trol group’s performance on test T2b. A p-value of
D
ISCUSSION
Despite numerous studies highlighting the mor-
bidity and mortality associated with iatrogenic
medication errors, this subject was rarely publicly
discussed until recently. Medication errors may ac-
count for up to 54% of iatrogenic cardiac arrests6,
and many of these are presumably preventable.
Errors in drug administration include uninten-
tional drug overdosing as well as underdosing;
these may be unrecognized causes of treatment
failure or side effects. Given the difficulty in simply
defining and recognizing medication errors, accu-
<
0.05 was considered statistically significant.
RESULTS
The study group consisted of 20 residents who rately determining the incidence of the problem
7
completed both test T1 and T2a. The mean score has proven difficult.

ACADEMIC EMERGENCY MEDICINE • November 2000, Volume 7, Number 11
1315
Unlike other industries where emphasis in both flect the greater availability of senior residents to
training and practice is placed on the avoidance of attend the weekly conference because of their de-
error, such imposed conformity is often considered creased clinical and off-service workload. Regard-
too intrusive in the practice of the art of medicine. less, the importance of this difference may be lim-
However, as scrutiny of medication errors in- ited, since the mean scores on both exams were
creased over the previous decade, and the scope of independent of postgraduate year. That is, the
the problem was realized, mechanisms to reduce ability to perform the calculations and ordering re-
or eliminate such adverse events have been ac- quired for this exam did not improve in the ex-
tively sought. Since dose calculation and ordering pected fashion based on extent of prior training.
are an early step in the medication administration The implications of this finding are unknown, but
process, and are uniquely physician-based, inter- suggest that, without formal training, this skill
vention at this point could reduce the incidence of may not be developed independently.
actual medication error. Instruction on proper
Several key issues remain. Overall, despite the
medication ordering, unfortunately, has not tradi- improvement shown by our intervention, there is
tionally been a significant part of formal medical a need to augment EM residents’ skills in this vital
education.
area. Even following the intervention, the physi-
It appears that EM residents are in need of fur- cians were only correct on 70% of the questions.
ther education regarding medication ordering. Furthermore, while showing significant six-week
This is clearly demonstrated by the 48% initial improvement, this study does not address the is-
mean score on the examination. Similar results sues of long-term retention.
were reported among primary care and pediatric
Tremendous effort and expense is, appropri-
residents using a similar case-based format to ately, being invested to limit the occurrence of
8
ours. Although testing is only a surrogate for ac- medication errors through the use of direct phar-
9
tual clinical practice, we used realistic clinical sce- macist participation, computerized drug ordering
10
narios. Whether this translates into an inability to systems, and systematic changes in drug deliv-
perform under real clinical conditions, where more ery. The primary responsibility for correct medi-
resources are normally available, is unclear. How- cation dose calculation and ordering remains with
ever, this examination tested concepts of dose cal- the prescribing physician. Emergency medicine
culation and order writing and not factual knowl- residency programs may need to place greater em-
edge. All information required for deriving the phasis on teaching these critical skills.
correct dose was provided in the questions.
Testing using simulated clinical circumstances,
L
IMITATIONS AND FUTURE QUESTIONS
followed by a brief period of discussion, provides
immediate feedback for the resident concerning ar-
eas of educational need. Rather than education
provided without a tangible clinical connection, as
is often done with standard lectures, a targeted in-
tervention provides contextual learning and may
enhance interest and retention.
The 30-minute directed intervention described
in this study produced a significant improvement
in residents’ abilities to successfully calculate com-
plex medication dosages. The mean improvement
was 30 points, and the majority of subjects showed
an improvement in their scores. However, this
study could not control for the effect of repetitive
test taking, in which merely taking the initial test
has a salutary influence on subsequent testing.
The dramatic improvement using different ques-
tions suggests that this was not the sole influence
on test improvement. Furthermore, even if the
simple act of taking a test produced an improve-
ment in this endpoint, the outcome would be
equally valid.
This study has several potential limitations. The
study and control groups differed in their distri-
butions of residents based on PGY level of training.
However, there did not appear to be an improve-
ment in test scores as training level advanced. We
used a question set that has never been formally
validated. The fact that we observed residents
from only a single residency program calls into
question whether these results can be extrapolated
to other EM residents. Additionally, the study
group was limited to the number of residents avail-
able at our institution. Most importantly, while
those residents who took part in the educational
session had a marked improvement in their skills
involving simulated dosage calculations and drug
ordering, we did not assess such skills in a real
clinical environment. Also, this study evaluated
only the effect seen at six weeks; further study is
warranted in order to determine whether these im-
provements persist.
The study and control groups differed in their
distributions of residents based on level of train-
ing. The reason for this is unclear, since the con-
CONCLUSIONS
ference is mandatory for all residents. It may re- A brief intervention regarding simulated drug dose

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DOSING EDUCATION
Nelson et al. • BENEFIT OF EDUCATION ON MEDICATION DOSING
4
. Lesar TS, Briceland L, Stein DS. Factors related to errors
in medication prescribing. JAMA. 1997; 277:312–7.
. Folli HL, Poole RL, Benitz WE, Russo JC. Medication error
prevention by clinical pharmacists in two children’s hospitals.
calculations and medication ordering significantly
improved the ability of EM residents to perform
these critical tasks. Whether this effect persists be-
5
yond six weeks is unknown. The need for further Pediatrics. 1987; 79:718–22.
6
. Bedell SE, Deitz DC, Leeman D, Delbanco TL. Incidence
improvement is evident.
and characteristics of preventable iatrogenic cardiac arrest.
JAMA. 1991; 265:2815–20.
References
7
. McGinnis JM, Foege WH. Actual cause of death in the
United States. JAMA. 1993; 270:2207–12.
. Potts JM, Phelan KW. Deficiencies in calculation and ap-
1
. Kohn LT, Corrigan JM, Donaldson MS (eds). To Err Is Hu-
8
man: Building a Safer Health System. Report of the Institute
of Medicine. Washington, DC: National Academy Press, 1999.
plied mathematics skills in pediatrics among primary care in-
terns. Arch Pediatr Adolesc Med. 1996; 150:748–52.
2
. Brennan TA, Leape LL, Laird N, et al. Incidence of adverse
9. Leape LL, Cullen DJ, Dempsey Clapp M, et al. Pharmacist
events and negligence in hospitalized patients. Results of the
Harvard Medical Practice Study I. N Engl J Med. 1991; 324:
participation on physician rounds and adverse drug events in
the intensive care unit. JAMA. 1999; 282:267–70.
3
70–6.
10. Bates DW, Leape LL, Cullen DJ, et al. Effect of comput-
3
. Bates DW, Cullen DJ, Laird N, et al. Incidence of adverse
events and potential adverse drug events: Implications for pre- erized physician order entry and a team intervention on pre-
vention. JAMA. 1995; 274:29–34.
vention of serious medication errors. JAMA. 1998; 280:1311–6.
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