Running head: EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
Can Pulmonary Embolism Confidently be Excluded Using Revised Simplified Geneva?
College of St. Scholastica
Evidence Based Practice
PTH6730
Dan Huddart PT
April 23, 2014
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EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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Abstract
In 5 studies that reviewed the Wells, simplified Wells, simplified Geneva and revised simplified
Geneva, there was some evidence that a statistically significant difference exists between the
simplified Wells and revised simplified Geneva for prediction of PE. However, the subjective
component of the Wells might add to the accuracy of the rule compared to Geneva. Pure
clinician gestalt in one study showed significance over the two rules. Further regression analysis
and study is warranted. A literature search was performed to locate retrospective and
prospective studies that compare two CDRs published after 2008 using keywords 'pulmonary
embolism', 'wells', 'geneva' and 'decision rules'. Within these five studies, a total of 2449
subjects was examined for pulmonary embolism probability and prevalence. It was concluded
that the revised simplified Geneva can be used with a high degree of certainty in excluding
pulmonary embolism.
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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Pulmonary embolism in the United States is increasing in incidence with the use of
computed tomography(CT), rising from 47 to 63 per 100,000 patients from 1997 to 2001 (mean
of 0.004% per year, P < .001) (DeMonaco, Dang, Kapoor, & Ragni, 2008). Pulmonary
embolism(PE) involves the obstruction of a part of the pulmonary vasculature from thrombus, air
bubble, fat globule, bacterial clump, amniotic fluid or dislodged heart valve vegetation
(Goodman & Snyder, 2013). This blockage from PE causes the lung tissue to become ischemic,
and a pulmonary infarct can develop. If this ischemia reaches the pleura, acute chest pain can
develop (Goodman & Snyder, 2013). Ten to 30% of people will die within one month of
diagnosis from PE. Sudden death is the first symptom in about one-quarter (25%) of people who
have a PE. One-third (about 33%) of people with DVT/PE will have a recurrence within 10
years (Beckman, Hooper, Critchley, & Ortel, 2010).
In the home health setting, a physical therapist is sometimes presented with signs that
may identify this life-threatening PE. It is beyond the scope of physical therapists to diagnose
systemic conditions. Referral by physical therapist or allied health professional to a physician
when a patient has any combination of systemic signs or symptoms is their obligation. Early
detection and management of PE can be life saving. It is important to have an objective clinical
decision rule that is validated for clinical signs of PE. It is in the scope of Physical Therapy
(PT) to identify these clinical signs. Physical therapists have used the Wells prediction tool in an
outpatient setting to screen for DVT. Wells prediction tool has been proven to be a valid
assessment tool as Goodman and Snyder (2013) suggest. However, the simplified Wells uses
one highly subjective category that involves an alternative diagnosis being suspected as less
possible for patient symptoms of PE. As with any test using subjective criteria, bias and
unreliability arise. One concern, is that variable falling outside the scope of PT. Determining
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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that an alternative diagnosis is less likely requires a PT to explore systemic options that some
would question. Having a clinical test that is objective, reliable and valid in identifying PE is an
important clinical procedure for two reasons. PE is life threatening if left undiscovered and it is
costly to provide a CT scan (gold standard) to every patient suspected of having PE. Finding
better objective methods for physicians and other allied health professionals to develop a
likelihood of PE is advantageous for these two reasons. This review will compare the simplified
revised Geneva (SRG) with the Wells test. In addition, this review will compare the two level
scoring, PE likely and PE unlikely, from each test.
Note. Wells rule, simplified Wells, revised Geneva and Simplified Revised Geneva (CDR)
Adapted from "Performance of 4 clinical Decision Rules in the Diagnostic Management of Acute
Pulmonary Embolism" by Douma, R. A., Mos, I. C. M., Erkens, P. M. G., Nizet, T. A. C.,
Durian, M. F., Hovens, M. M., . . . Huisman, M. V. (2011) Annals of Internal Medicine, 154(11),
p 710.
Table 1
Clinical Decision Rules
Wells Rule
Previous PE or DVT
Heart rate>100
Surgery or immobilization in 4wks
Hemoptysis
Active CA
Clinical signs DVT
Alternative Dx less likely than PE
PE Likely
PE Unlikely
Clinical Probability
Low
Medium
High
Revised Geneva Rule
Previous PE or DVT
Original
1.5
1.5
1.5
1
1
3
3
<=4
>4
Simplified
1
1
1
1
1
1
1
<=1
>1
<2
2-6
>6
3
1
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
Heart rate 75-94
Heart Rate >=95
Surgery or fracture in 1 month
Hemoptysis
Active Cancer
Unilateral lower limb pain
Pain on lower limb deep vein palpation
and unilateral edema
Age >65 years
PE Likely
PE Unlikely
Clinical Probability
Low
Medium
High
5
3
5
2
2
2
3
4
2
1
1
1
1
1
1
1
<=5
>5
1
<=2
>2
<3
4-10
>10
A literature search was conducted between March 2 through April 4 of 2014 using
Medline and keywords Pulmonary embolism(PE) and Geneva. These keywords revealed 18
articles of which one was omitted for language barrier and the other 13 were of a specific nature
and population not within the parameters of this review. In addition research published after
2008 was used as a prerequisite. Using keywords pulmonary embolism and wells revealed 37
articles and two were duplicates from the earlier search. The others were of dated publication
prior to 2008, were meta analysis or were not relevant. Mesh terms for pulmonary embolism did
not aid in this search of articles. The following research is chosen for review as they compared
RSG and Wells within outpatients or emergency units. One of these studies for review was
found through a "smart search" while examining a meta analysis of these rules. One additional
study (Penaloza, Verschuren, Meyer, Quentin-Georget, Soulie, Thys, & Roy, 2013) compares
gestalt to Wells and revised Geneva.
Critical Reviews
Penaloza, Melot, & Motte, (2011) examined 339 outpatients with suspected PE that were
gathered from two previous prospective management studies in an academic hospital to compare
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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predictive accuracy of the Wells with SRG. The authors of the research found subjects from the
hospital emergency records between the age of 18 to 94 with 57% being female and mean age
being 56. The actual signs and symptoms of PE used to assess for inclusion into the study are
not revealed and similarly the exclusion criteria was not revealed. This study is applicable to the
home health setting as both outpatients and home health patients are community dwellers and of
similar age ranges.
The attending physicians filled out the Wells scoring sheet and subjects were placed into
three levels of probability creating ordinal data. A diagnostic workup including; D-dimer, v/q
lung scan, leg compression ultrasonography and helical CT were performed on suspected PE
patients depending upon the subjects probability scoring. The authors of the study did not reveal
how many patients had each corresponding diagnostic test and no one gold standard were used
but rather a D-dimer, CT, V/Q or ultrasonography was used to diagnosis definitively based on
the probability from the Wells test. The RSG scores were gathered retrospectively from the
charts in a blind manner and statistics calculated using chi square and Mantel-Haenzel tests. A
two level scoring of PE likely or PE unlikely is binomial, and the Mantel-Haenzel test is
appropriate for comparison and analysis.
If the patient was classified in the low or medium probability group (referred to as nonhigh) and a D-dimer was done with a normal result they were deemed negative for PE. All
patients were followed for three months for DVT. If the patient fell in the high probability a V/Q
lung scan, CT or venous ultrasound was performed to identify PE. Again these patients were
followed for three months.
The amount of agreement between Wells and SRG is fairly weak. It shows a kappa
coefficient =.369. Kappa .8 or higher would indicate that the agreement of Wells and SRG is
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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good with chance eliminated. This fairly weak score of .369 indicates chance plays a role in
agreement. Due to the lack of agreement 35% of the patients were classified differently. And it
is important to note major disagreement did not occur. Major disagreement is one being
classified as high probability by one score and low probability by the other. Due to this
disagreement downgrading and upgrading occurred. Comparing the medium and high
probability Wells patients to the RSG shows that 40 in total were downgraded. Thirty had
initially been categorized as medium by Wells and using the RSG they were shifted to low
probability. Ten from the high Wells were downgraded to medium using the RSG. Of these 40
downgraded patients 34% (CI,22-51) had PE. Of particular concern for allied health
professionals is the criteria in the Wells determining alternative diagnosis not likely compared to
PE being scored in favor of PE in all 40 downgraded patients. That question has a heavy three
point weight and contributes to the higher pretest score using the Wells.
This paper also retrospectively applied the two level scoring system for the Wells and
RSG. This scoring system attempts to classify patients either as PE likely or unlikely. The
sensitivity was 70%, and specificity was 78% using the Wells. According to the researchers, the
Wells did statistically significantly better than RSG (p<.001). The sensitivity and specificity or
RSG was respectively 66% and 74%, but this data had to be extrapolated by this reviewer and
wasn't provided.
This study computed the Area Under the Curve (AUC) in the Receiver Operator Characteristic
(ROC) curve for both the Wells and RSG. When this was plotted the Wells did significantly
better (p=.005) with .85(.81-.89) versus .76(.71-.80) respectively.
There is one particular noteworthy limitation in the nature of the data collection for the
rules. The researchers gathered RSG data retrospectively, but it was blinded, and these scores
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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are objective. In addition, the patients were followed prospectively for three months. However,
the retrospective score assessment is compounded by the lack of information about how the
patients were selected. No inclusion or exclusion criteria were accounted. Because of this lack
of criteria coupled with the fact, this is an outpatient setting makes direct comparison to home
health population questionable. Secondly, the number of patients who underwent CT was not
divulged and no single gold standard of test verification was utilized. Third, the degree of
agreement was weak with 119 total patients (35%) being classified differently. The three factors
contributing to disagreement are the subjective Wells criteria, age that is only taken into account
with the RSG and heart rate which is weighted differently.
The purpose of the Wells or the RSG rules is to allow the clinician to categorize a patient
into one of three probability classes or simply ruling a patient as likely or unlikely using the two
level scoring. Using the three levels of probability, a physician can determine which test to
diagnose PE. For example, if the probability is low for PE and the rule is fairly specific with few
false negatives, a physician could rely upon a low cost D-dimer to rule out PE. Similarly, this
would apply for the medium level of probability. One would want to see very few patients in the
low to medium classes as having PE, reflecting good specificity and high numbers of true
negative. These clinical tests should do well at ruling out PE, as well. The high probability class
would have a very high likelihood of PE and these tests should approach nearly 100% of those
categorized here as having PE, indicating high sensitivity and large numbers of true positives.
Several conclusions can be made from this research. The Wells scored significantly
better (p<.05) as compared to RSG in the high probability group in predicting PE accurately 93%
(CI, 70-99). Second the 2 level scoring reveals statistical advantage to the Wells (p<.001) in
predicting PE likely as compared to the RSG. Third the area under the curve (AUC) for the
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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Wells did significantly better (p=.005) with .85(CI, .81-.89) versus the RSG of .76(CI, .71-.80).
The degree to which clinical judgment plays in contributing to the significance of the Wells over
the RSG is questioned in this review.
Wong, Ramaseshan, & Mendelson, (2011) conducted a prospective cohort study of 98
consecutive patients from the emergency department in Australia in 2008 to directly compare the
diagnostic accuracy of simplified Wells and RSG. The RSG score was retrospectively gathered
by blinded researchers. The research did not reveal any exclusion criteria but admission
symptoms were chest pain, shortness of breath, mixed chest pain and shortness of breath,
syncope and hemoptysis. Patients were classified into three probabilities and those with low
probability were scanned with V/Q scintigraphy to detect PE. Those in the medium or high
probability were diagnosed with CT. Mcnemar's test was used on dichotomized data after the
scores were broken down into two levels, PE likely and unlikely.
The PE prevalence was 15.3%. Using the simplified Wells for the low, medium and high
probabilities, the proportions were 65.3%, 32.7% and 2.0% respectively. The prevalence of PE
in each respective probability group was 12.5%, 18.8% and 50%. Using the RSG for the low,
medium and high probabilities, the proportions were 42.9%, 51% and 6.1% respectively. The
prevalence of confirmed PE was 7.1%, 18% and 50% in respective probability groups in RSG.
There were no cases of a major discordance, where one rule was high and the other low. But the
two scores had 40.8% disagreement between two scores. The kappa was .26(CI, 0.1 - 0.42).
After dichotomizing the rules into PE likely and unlikely the sensitivity of the simplified
Wells was 46.7% (CI, 21.4-79.9), and the RSG was 80% (CI, 59.8- 100). The authors deemed
this borderline statistical significance (p=.06). The specificity of the Wells was statistically
higher than RSG with 67.5% (CI, 57.4-77.6) and 47% (CI, 36.3- 57.7) with p=.002 respectively.
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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The area under the receiver operator characteristic curve for the two rules was not significantly
different at .62 and .65 for simplified Wells and RSG respectively (p=.617).
The primary limitation of this study is the small size and low prevalence. Insufficient
power leads to type two errors. In this study, there were eight false negative simplified Wells
patients versus three RSG. Second, there is poor agreement with the two rules having 40.8%
discordance. In this review, it was found that RSG upgraded patients into medium or high
probabilities. Finally, the patients that were classified in a low probability and had a normal Ddimer were not followed up with CT to find any additional false negatives. Having a D-dimer
rule out PE is normal clinical practice (Geersing, Erkens, Lucassen, Büller, Cate, Hoes, . . .
Stoffers, (2012), although a scientific study would better utilize CT on everyone.
The conclusion of this study shows that despite lack of agreement of PE in corresponding
probability groups the prevalence of PE in each group, low, medium and high is similar (P>.05)
in the two CDRs. The authors in this study state that the subjective nature of the Wells maybe
responsible for much of the specificity and predictive value. Finally, there was borderline
significance (P=.06) in sensitivity favoring RSG.
Douma, Mos, Erkens, Nizet, Durian, Hovens, . . . Huisman (2011) conducted a
prospective cohort study of 807 patients between July 2008 and November 2009. They included
outpatients and inpatients that had signs of PE; sudden onset of dyspnea, deterioration of existing
dyspnea, or sudden onset of pleuritic chest pain. Patients were excluded if <18, life expectancy
less than three months, treatment with therapeutic-dose heparin or unfractionated heparin that
was initiated 24 hours or more before assessment for research admittance, treatment with vitamin
K antagonists, previous diagnosis of PE, contraindication to CT or allergy to contrast, renal
insufficiency, pregnancy and inability to follow up. The researchers used a power analysis of
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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90% with an alpha of .05 and calculated the need for 128 positive CT results that would be
needed for detection of 5% difference in sensitivity of the two rules. The purpose of the
research was to directly compare the rules in their ability to exclude PE in combination with a
normal D-dimer when two level scoring is used (PE likely versus unlikely).
The sequence of testing started with classification into the probability groups using
computer programs. All patients for whom PE was ruled out were followed for three months to
further insure PE didn't develop. D-dimer was done on patients who had all four rules testing as
PE unlikely. If D-dimer was normal, PE was ruled out and 169 patients fell into this category.
265 patients had abnormal D-dimer and were sent for CT scan. If one of the four rules showed
disagreement a CT was done. 243 patients had disagreement and 130 had all rules predicting PE
likely. Protocol dictated that CT would be done on all these patients. The overall prevalence of
PE was 23% (CI, 20-26%).
The simplified Wells placed 62% (CI, 59-65), and the RSG placed 71% (CI, 68-75) into
PE unlikely category. The prevalence of PE in each respective rule for PE unlikely was 13%(CI,
10-16) and 17%(CI, 14-20). Adding the normal D-dimer to the PE unlikely groups revealed
22%(CI, 19-25) and 24% (CI, 21-27) as classified with simplified Wells and RSG respectively.
The incidence of PE in this group of normal D-dimer and PE unlikely was .6% (CI, 0.0 - 3.0) in
the simplified Wells and .5% (CI, 0.0 - 2.9) in the RSG. The proportion of patients with PE
likely was 38%(CI, 35-41) and 29%(CI, 26-32) for simplified Wells and RSG respectively. Of
these 39%(CI, 34-44) of the simplified Wells had PE confirmed, and RSG had 39% (CI, 32-45).
Discordance was found to be 25% between the simplified Wells and the RSG.
Sensitivity of the rules without D-dimer was 65% for simplified Wells and 80% for the RSG.
When combining the D-dimer the sensitivities did not differ. The simplified Wells and RSG
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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were both 99.5% (CI, 97-100) but the specificities differed. The simplified Wells got 29% (CI,
25-33), and the RSG was 31% (CI, 28-34). The negative predictive value was 99.4% for
simplified Wells and 99.5% for the RSG. Despite the discordant scores, the two rules performed
equally in excluding PE. Finally, the AUC for the two rules was not significantly different.
There are a few limitations. First there were some protocol violations with four patients
in need of CT not receiving CT. However, three months follow up didn't reveal PE. Second,
protocol was based on all 4 CDR being used to determine the need for CT with the D-dimer
result rather than one CDR in combination with D-dimer. Third, due to the larger portion of
outpatient vs. inpatient sample size (644 versus 163) in this study the relevance to PE exclusion
in inpatients is limited with these rules. Fourth, it did not include patients with recurrent PE.
Hence, patients in a clinical setting that present with a history of PE would have different
comparison.
The authors concluded that four rules in combination with D-dimer all performed
similarly in exclusion of PE. This review prospectively validates the RSG in a fairly large
sample of outpatients.
Calisir, Yavas, Ozkan, Alatas, Cevik, Ergun, & Sahin, (2009) examined the diagnostic
accuracy of simplified Wells and RSG and predictive ability for PE in emergency units and
inpatients. Inclusion and exclusion criteria are not found in this research, but 167 patients were
suspected of PE and underwent scoring via the two CDRs. CT angiography or CT venography
was done on all patients depending upon the area of suspected PE. The images using CT for
diagnosis were only adequate for 148 patients due to image artifacts.
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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All 148 patients were followed for three months. Radiologists were blinded to the CDR
scores and diagnosed patients from either CT, V/Q scintigraphy, angiography indicating
intraluminal filling defect of a thrombus obstructing a vessel, or venous ultrasound showing
DVT. Medical students collected the two CDR scores in a blinded fashion. Data collection was
reviewed by members of the study to insure no data was missed.
PE prevalence was 32%. Patients were grouped into high, medium and low probability
with the Wells grouping 19.5%, 46% and 34.5% and the RSG grouping 16, 74% and 10%
respectively. The actual rates of PE in each CDR and high, medium and low groups were
89.6%, 26.4%, 7.8% for the Wells and 83.3%, 25.6% and 0% for RSG. No statistical
significance can be found between these two CDRs prevalence nor probabilities (P>.05). The K
analysis shows .398 agreement. The AUC was significantly greater for the Wells (.823) than the
RSG (.732) when all patients were considered (P=.004). If only the 104 emergency unit patients
were analyzed, the RSG was not significantly different (P=.07).
The primary limitation of this study is the high rate of artifacts on CT that led to attrition
of 13% of subjects. Finally, the prevalence was also somewhat high and the authors suggest a
relationship to a higher threshold of PE suspicion.
The main conclusion of this study is that the Wells is more accurate at predicting PE in a
population of inpatients and emergency units, but the RSG was found to be just as accurate when
only the emergency population was analyzed. Agreement of the two CDRs continues to be poor.
The rate of PE prevalence within each probability group was not significantly different. The
authors stated that, within the emergency, department sample, the RSG can be used with high
reliability.
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Penaloza, Verschuren, Meyer, Quentin-Georget, Soulie, Thys, & Roy (2013)
conducted a retrospective analysis of a prospective observational cohort study to compare the
degree of agreement between three methods of determining the probability of PE in emergency
units. The purpose was to determine if a clinician's unstructured gestalt was any different at
predicting PE as compared to the RSG and the simplified Wells. The authors hypothesized that a
gestalt assessment could compare favorably to CDRs. 116 emergency units in France and one in
Belgium were used for assessing 1,529 subjects suspected of PE. Patients were excluded if PE
was documented prior to admission; PE was suspected among inpatients of two days or more, or
if diagnostic testing was not performed due to death, refusal or ethical reasons. Ultimately 1038
subjects were included.
Gestalt is the professional clinical judgement, cultivated by personal experience and
established through the subjects history and physical. Chad Cook PT Ph.D. writes that "Clinical
gestalt is the theory that healthcare practitioners actively organize clinical perceptions into
coherent construct wholes. This implies that clinicians have the ability to indirectly make clinical
decisions in absence of complete information and can generate solutions that are characterized
by generalizations that allow transfer from one problem to the next. At present, the literature
suggests that experience does positively influence decision-making accuracy as experienced
clinicians have better pattern recognition skills." (Chad, 2009).
Patients in this research were approached first by their physicians with a standardized
form to gather characteristics to formulate the gestalt into low, medium and high probability of
PE. This gestalt was done prior to any diagnostic testing or rules determination. The next step
was to retrospectively compute the Wells and the revised Geneva (RG) from the patient
standardized data collection sheets and medical records. These three assessment methods
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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classified patients into three probability categories and then PE was determined by CT,
angiography, V/Q scan, ultrasound or follow up or death indicating DVT or PE. Patients and
their general practitioners were interviewed at the end of three months follow-up period to assess
the occurrence of PE or DVT. Significance was set at P<.05 and CI were 95%.
The prevalence of PE was 31.3%. This prevalence is rather high compared to other
studies. The three groups had significant differences between themselves with respect to
prevalence. The low probability gestalt had significantly less PE 7.6% (CI, 5.4 -10.4%)
compared to 12.6% (CI, 9.8 - 15.4) Wells and 13% (CI, 9.3 -7.4) RG. In addition, there was
significance in the high probability group when comparing gestalt to the Wells. 72.1%(CI,66.377.4) of the gestalt had PE in the high group and 58.1%(CI, 46.7-68.9) in the Wells, but no
significant difference was found with RG of 68.7% (CI, 59.1- 77.2). When combining the low
and medium into a category called non-high, which is often the category used for D-dimer test to
rule out PE, the gestalt did significantly better at having a lower prevalence of PE than both
Wells and RG. Moreover, the gestalt had the best AUC with .81(CI, .78-.84) compared to Wells
.71(CI, .68 - .75) and RG .66(CI, .63 - .70). This study shows overall poor agreement with
kappa of .21(CI, .17-.25) comparing gestalt to RG, .25%(CI, .20-.29) gestalt versus Wells and
.26(CI, .21 - .31) Wells versus RG. Major disagreement did occur, where one rule was low and
the other high. In the comparison of gestalt versus RG, 3% of subjects had a major disagreement
and 4% had disagreement comparing gestalt versus Wells. There was less disagreement
comparing Wells to RG with only 1% having major disagreement.
The study authors admit to some limitations. Firstly, there is a high prevalence of PE that
could be due to the differences in suspicion threshold for PE. If the clinicians have a high
threshold for suspecting PE when using gestalt or when using Wells the clinician places a higher
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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suspicion of an alternative diagnosis, the prevalence increases. In addition, there were 22 deaths
in which no autopsy was conducted but PE was concluded as the means of death. This again can
add to the prevalence and false positive numbers. Secondly, this study is a retrospective
analysis of a prior study and thus only the patients from the original study who had validated
diagnostic studies where included. Thirdly, no single diagnostic criteria was done on all patients
and the Wells subjective criteria of the alternative diagnosis being less likely was extrapolated
and not specifically identified by the bedside clinician. Fourth, the authors admit that 168
physicians used a CDR during their gestalt assessment. The major limitation of gestalt theory is
the heterogenous training associated in medical schools leading to different standards of practice.
The authors conclusions from this study are that gestalt is better than CDR in having less
PE prevalence in the low probability group and a significantly better area under the ROC curve
than the two rules. These authors feel that the subjective nature of gestalt which allows the
physician to take into account all signs and symptoms of PE contributes to better performance.
Discussion
Incidence of PE varies by continent. Some of these studies were not in North America.
Due to the higher threshold of prediction in the non North American countries, prevalence will
change (Penaloza et al., 2012). Two emergency department physicians in the United States,
Newman and Weingart, are beginning to question the actual mortality risk of PE. According to
Newman & Weingart [Video] (2011), the prevalence of PE may be higher than what is
documented as they are finding segmental PE in 20% of patients that are getting CTs after car
accidents. These two physicians are questioning whether it might be a normal physiologic
response to have segmental PE. Regardless, the litigation risk and negligence inherent in not
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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identifying the signs of PE, outweighs the possible facts related to PE and mortality that might be
gleaned in the next few decades from continued autopsy and disease research.
PE is costly to identify by CT. Some PE tests have risks all to themselves such as renal
failure from contrast or radiation exposure. No single method of identifying clinical probability
of PE most accurately has been identified. PE has many variable symptoms and a non specific
nature of clinical presentation. Therefore, allied health professionals have a clear disadvantage
in identifying PE as compared to physicians. Primarily since physical therapists cannot diagnose
systemic ailments. The Wells rule with its subjective gestalt-like variable compounds the
difficulty experienced by physical therapists.
Identifying a standardized objective alternative that is reliable and valid would be
advantageous for allied health professionals. Considering the abundant clinical signs and various
components of patients history that are involved with identifying PE, one can sympathize with
the difficulty in identifying this standardized objective rule.
This paper examined the 5 studies to determine the importance of the subjective nature of
Wells in PE probability prediction and actual prevalence, in contrast to the objective Geneva.
All five studies substantiate the overall lack of agreement in these CDRs. However, the
conclusions drawn by the two studies Wong et al., (2011) and Penaloza et al., (2013) lends
support and confidence for the use of RSG since the prevalence of PE in each probability group
was similar.
Although the first study by Penaloza et al., (2011), favored the Wells in the high
probability group and the overall two level scoring and the area under the ROC curve for
specificity. The second study by Penaloza et al., (2013), showed an equal area under the ROC
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
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curve for specificity with both CDR. In addition this latter study in 2013 by Penaloza et al.,
demonstrates a similar prevalence of PE in the low and high groups using Wells and RG.
Therefore, two studies show that RSG can be used with good confidence to classify patients by
allied health professionals.
Finally, in support of the objective Geneva, the study by Calisir et al.,(2009), looked at
inpatients and emergency department patients. Emergency department patients could be
categorized in the same sample of home health patients. The ER is where a home health patient
is sent for work up if PE is suspected by a CDR in the home. These authors state RSG is better
at predicting PE in emergency department patients. In addition, Douma et al., in 2011 used a
larger sample of outpatients, another similar group to home health, and validated the RSG. To
go even further, there was no significant difference with area under the ROC curve for any of the
rules.
Despite this evidence in favor of the RSG the simplified Wells outperformed with area
under ROC curve in three out of 5 studies.
Conclusion
Allied health professionals should keep in mind that due to the clinical skills and gestalt
ability of physicians, the CDRs may not be nearly as accurate in identifying probability of PE.
The study by Penaloza et al., (2013) clearly shows the significance of the gestalt over all CDRs.
With the generation of better predictive variables through regression analysis and other statistical
methods a better objective test may introduce itself. In the meantime, use of the Wells or the
RSG can be used by physical therapists and other allied health professionals with a high degree
of confidence in excluding PE in home health patients.
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References
Beckman, M. G., Hooper, W. C., Critchley, S. E., & Ortel, T. L. (2010). Venous
thromboembolism: a public health concern. Am J Prev Med, 38(4 Suppl), S495-501. doi:
10.1016/j.amepre.2009.12.017
Calisir, C., Yavas, U. S., Ozkan, I. R., Alatas, F., Cevik, A., Ergun, N., & Sahin, F. (2009).
Performance of the Wells and Revised Geneva scores for predicting pulmonary
embolism. European Journal Of Emergency Medicine: Official Journal Of The European
Society For Emergency Medicine, 16(1), 49-52. doi: 10.1097/MEJ.0b013e328304ae6d
Chad, C. (2009). Is Clinical Gestalt Good Enough? J Man Manip Ther, 17(1), 6-7.
DeMonaco, N. A., Dang, Q., Kapoor, W. N., & Ragni, M. V. (2008). Pulmonary embolism
incidence is increasing with use of spiral computed tomography. Am J Med, 121(7), 611617. doi: 10.1016/j.amjmed.2008.02.035
Douma, R. A., Mos, I. C. M., Erkens, P. M. G., Nizet, T. A. C., Durian, M. F., Hovens, M. M., . .
. Huisman, M. V. (2011). Performance of 4 clinical decision rules in the diagnostic
management of acute pulmonary embolism: a prospective cohort study. Annals Of
Internal Medicine, 154(11), 709-718. doi: 10.7326/0003-4819-154-11-201106070-00002
Geersing, G.-J., Erkens, P. M. G., Lucassen, W. A. M., Büller, H. R., Cate, H. t., Hoes, A. W., . .
. Stoffers, H. E. J. H. (2012). Safe exclusion of pulmonary embolism using the Wells rule
and qualitative D-dimer testing in primary care: prospective cohort study. BMJ, 345. doi:
10.1136/bmj.e6564
Goodman, C. C., & Snyder, T. E. K. (2012). Differential Diagnosis for Physical Therapists:
Screening for Referral: Elsevier Science Health Science Division.
EXCLUDING PULMONARY EMBOLISM WITH REVISED SIMPLIFIED GENEVA
20
Newman v Weingart: Pulmonary Embolism Showdown[Video]. (2011). Retrieved from
http://vimeo.com/25790659
Penaloza, A., Kline, J., Verschuren, F., Courtney, D. M., Zech, F., Derrien, B., . . . Roy, P. M.
(2012). European and American suspected and confirmed pulmonary embolism
populations: comparison and analysis. Journal of Thrombosis and Haemostasis, 10(3),
375-381. doi: 10.1111/j.1538-7836.2012.04631.x
Penaloza, A., Melot, C., & Motte, S. (2011). Comparison of the Wells score with the simplified
revised Geneva score for assessing pretest probability of pulmonary embolism.
Thrombosis Research, 127(2), 81-84. doi: 10.1016/j.thromres.2010.10.026
Penaloza, A., Verschuren, F., Meyer, G., Quentin-Georget, S., Soulie, C., Thys, F., & Roy, P. M.
(2013). Comparison of the unstructured clinician gestalt, the wells score, and the revised
Geneva score to estimate pretest probability for suspected pulmonary embolism. Ann
Emerg Med, 62(2), 117-124.e112. doi: 10.1016/j.annemergmed.2012.11.002
Wong, D. D., Ramaseshan, G., & Mendelson, R. M. (2011). Comparison of the Wells and
Revised Geneva Scores for the diagnosis of pulmonary embolism: an Australian
experience. Internal Medicine Journal, 41(3), 258-263. doi: 10.1111/j.14455994.2010.02204.x