what diagnostic strategies can help differentiate
TRANSCRIPT
What diagnostic strategies can help differentiate cellulitis from other causes of red legs in adults presenting to primary care
Article (Accepted Version)
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Edwards, G, Freeman, K, Llewelyn, M J and Harward, G (2019) What diagnostic strategies can help differentiate cellulitis from other causes of red legs in adults presenting to primary care. British Medical Journal (BMJ). ISSN 1759-2151 (Accepted)
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1
What diagnostic strategies can help differentiate cellulitis from other causes of red legs in
adults presenting to primary care?
Edwards G1 (0000-0002-0048-4178), Freeman K2 (0000-0002-9963-2918), Llewelyn, MJ
(0000-0002-6811-1124), Hayward G1 (0000-0003-0852-627X)
1: Nuffield Department of Primary Care Health Sciences, Radcliffe Observatory Quarter, Woodstock
Road, Oxford, OX2 6GG
2 Warwick Medical School, Division of Health Sciences, University of Warwick, Gibbet Hill Road,
Coventry, CV4 7ALCorrespondence to: Gail Hayward – [email protected]
3 Brighton and Sussex Medical School, Division of Global Health and Infection, University of Sussex,
Falmer, BN1 9PS
2
Red legs are a common presenting problem in general practice, particularly in older adults,
and have multiple potential causes. Cellulitis is the most common bacterial infection causing
red legs; 127,480 cases were managed in UK hospitals in 2017-18.1 The true incidence,
including cases managed through primary care, is likely to be much higher. International
guidelines recommend antibiotic treatment for all cases of cellulitis, and hospitalisation in
more severe cases.2–5
Diagnosis of cellulitis is challenging. In addition to redness, common symptoms are the
classic signs of inflammation: tenderness, warmth and swelling. These symptoms are
common6 and a variety of other causes of red legs can present with some, or all, of these
symptoms (see table 1). Consequently misdiagnosis of these conditions as cellulitis is high.
Studies in U.S. Emergency Departments (EDs) have reported that between 28% and 30.7%7–9
of cellulitis diagnoses made by ED physicians are incorrect.
Misdiagnosis of cellulitis has the potential to result in unnecessary antibiotic treatment,
often for extended periods in excess of 14 days,10 and avoidable hospitalisation. However
complications of untreated cellulitis include extensive tissue damage and necrosis,
disseminated infection, septic shock, and potentially death.11 In primary care, therefore, a
key diagnostic dilemma is the differentiation of red legs with bacterial causes from those with
non-infectious causes.
What is the evidence of uncertainty?
A recent systematic review and scoping review have highlighted the lack of validated
diagnostic aids for lower limb cellulitis.12,13 Our systematic search aimed to identify diagnostic
strategies for cellulitis of any site, acknowledging that the lower limb is the most common site
of cellulitis and therefore the focus of this review.14 We included 8 primary studies which have
investigated diagnostic strategies relevant to primary care and applicable to red legs.
The 8 small prospective or retrospective studies retrieved have investigated 4 different
diagnostic strategies: thermal imaging, clinical prediction scores, procalcitonin testing, and a
Visually-based computerized diagnostic decision support system (VCDDSS), detailed in Table
2. All approaches are non-invasive and potentially viable in primary care. Thermal cameras
are available as smart phone attachments, clinical decision support systems only require
3
compatibility with standard available computer software. Point of care tests are marketed
for procalcitonin and components of the prediction scores.
Approaches to diagnosis of cellulitis
Skin surface temperature
Thermal imaging has been used to compare the temperature of an area of suspected
cellulitis with a contralateral body site in two small cross-sectional studies of patients
presenting to the emergency department. Both found a temperature difference of 0.47°C
had a reasonable sensitivity (96.6% and 87.5% respectively) for cellulitis as diagnosed by
dermatologists. A conference abstract describes a sensitivity of 95.3% when using thermal
imaging together with diffuse reflectance spectroscopy (DRS) to differentiate cellulitis from
pseudocellulitis.15
Clinical prediction models
A cross-sectional study of 259 patients diagnosed with lower limb cellulitis in a U.S. ED was
used to develop the ALT-70 model for predicting the likelihood of lower extremity
cellulitis.16 Using final discharge diagnosis of cellulitis as a reference standard, 4 features
were found to be predictive of ‘true’ cellulitis: asymmetry (3 points), leucocytosis (1 point),
tachycardia (1 point), and age ≥70 (2 points). Unilateral leg involvement was associated with
an adjusted odds ratio of 8.65 for cellulitis, the highest of the four variables in the score.
Table 2 details performance using both >5 and >3 cut-offs in this study and a subsequent
small case control study which evaluated the ALT 70 alone, and in combination with thermal
imaging. In a retrospective cohort study of 57 patients, 20 with dermatologist confirmed
cellulitis,17 a score of 4/7 in a one point per criteria ‘NEWHAvUN’ score system (new onset,
erythema, warmth/fever, history of trauma, ache, unilaterality and number of white cells)
was 100% sensitive and 95% specific.
Visually-based computerized diagnostic decision support system (VCDDSS)
The VCDSS suggests alternative diagnoses in form of peer-reviewed photographs or
diagrams of medical conditions from the most to the least likely based on symptoms
4
inputted by the clinician. The VCDDSS more frequently included the correct alternative
diagnosis among non-cellulitis cases than the admitting physician (18/28 [64%] versus 4/28
[14%], p=0.0003) in 145 subjects hospitalized for presumed cellulitis from the ED.7 However,
the study did not explore whether use of the VCDDSS by ED physicians results in fewer
misdiagnoses.
Procalcitonin
In a case control study of 48 adult ED patients with erysipelas or deep vein thrombosis
[DVT]) diagnosed by the treating physician, patients with erysipelas had significantly higher
PCT concentrations than those with DVT.18 At a PCT threshold of 0.1 µg/L or more sensitivity
was 58.1%, specificity 82.4% and PPV 85.7%. In contrast, none of three histopathologically
confirmed cases of bacterial cellulitis had detectable PCT levels in a small case control study
of ED patients diagnosed with cellulitis or dermatitis.19
Summary
There is insufficient evidence to recommend implementation of any of these strategies in
primary care. In 7/8 studies reporting recruitment setting, recruitment was from EDs rather
than Primary Care, which may have resulted in a presenting population with more severe
symptoms. All of the studies used highly selective populations, including only patients who
were suspected to have cellulitis by an ED clinician or dermatologist and excluding patients
with a number of other relevant diagnoses such as soft tissue abscess, osteomyelitis, and
diabetic ulcers.8,16,20 In an undifferentiated primary care population test performance may
be poorer.
The quality of all studies, assessed using the QUADAS framework, was poor. In 5/8 studies it
was unclear whether the researchers using the novel tests were blind to the confirmed
diagnosis. Results were also potentially biased due to use of different methods to confirm
diagnosis (2/8 studies), or inappropriately long time intervals between the test of interest
and confirmation of disease (7/8 studies). Furthermore, one study was15 only available as an
abstract and did not provide a validation cohort, despite offering promising data. Finally, for
one study only preliminary data was available.7
5
Is ongoing research likely to provide relevant evidence?
We searched UK, EU, and USA registries for ongoing studies and found two of potential
relevance. The first, a prospective cohort study21, aims to evaluate the accuracy of non-
contact infrared measurement of skin temperature to distinguish limb cellulitis from
pseudocellulitis in 50 adults presenting. The second, a before and after study22 aims to
evaluate of point-of-care ultrasound to differentiate cellulitis from non-infected insect bite
in 304 children. Both of these studies will recruit from ED populations which are likely to be
more selective than those consulting to primary care. However, they use technologies
suitable for primary care and at least one appears well powered to evaluate diagnostic
accuracy.
A key challenge to progress in this field is the lack of a reference standard for ‘true’ cellulitis,
which remains a clinical diagnosis. No in vitro diagnostics can give a definitive diagnosis, at
least in part due to the lack of obvious substrate for testing. Superficial swab and blood
cultures are typically negative even in true cellulitis23,24 and rarely alter management.25
Culture and molecular testing of punch biopsy samples may be useful in patients at risk of
specific pathogens (e.g. animal or water exposure).11
Diagnosis of cellulitis by a dermatologist has been used in large intervention trials to define
the included population.26 In one large trial, two features from pain, swelling, warmth,
fever, lymphangitis, induration, or ulceration in addition to the clinician diagnosis of
bacterial infection were required for study entry.27 Dermatologist assessment was also used
in the majority of studies we identified as a proxy diagnostic reference standard. However,
neither in the large trials nor in these studies was there any description of how the
dermatologists reached their diagnosis.
What should we do in the light of the uncertainty?
Given the current limitations in the evidence for the use of novel diagnostic approaches in
primary care, clinical history and examination should remain the mainstay of diagnosis.
In clinical history, a recent systematic review identified the following factors as conferring
increased risk of cellulitis28:
6
Previous cellulitis
Lymphoedema/chronic leg oedema
Excoriating skin diseases
Tinea pedis or obvious site for infection to have penetrated through
BMI >30
On examination, recent overviews describe classic signs of cellulitis as acute unilateral
erythema, pain, heat, swelling, and tenderness.2,3,5 There may be ascending lymphangitis
and tender groin lymphadenopathy. The affected area may be well demarcated or diffuse
and the term erysipelas is no longer regarded as a distinct entity from cellulitis.2
In differentiating cellulitis from non-infective processes, although we cannot recommend
the approaches we found in our review, the studies indicate that a unilateral presentation is
associated with greatly increased odds of cellulitis. Bilateral cellulitis is uncommon but may
complicate chronic dependent oedema or lymphoedema.11 In unilaterally affected limbs, a
lack of elevated temperature compared to an unaffected limb can help to rule out cellulitis.
Active consideration of alternative diagnoses (Table 1), the approach supported by VCDSS,
may help clinicians avoid unnecessary antibiotic treatment. In particular, clinicians should
consider alternate diagnoses in patients with bilateral red legs and red legs which are not
warmer than other body parts. However, given the ongoing uncertainty and risk of
complications, antibiotic prescription is reasonable in cases where there is doubt. Referral
for hospital treatment should be considered in patients with signs of systemic toxicity or
uncontrolled co-morbidities.5 Identifying necrotising fasciitis requires a high index of
suspicion as characteristic features are often absent initially (table 1) and emergency
referral to hospital for investigation is indicated.29
7
References:
1. https://digital.nhs.uk/data-and-information/publications/statistical/hospital-admitted-patient-care-activity/2017-18.
2. Stevens, D. L. et al. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Clin. Infect. Dis. 59, e10–e52 (2014).
3. CREST. Guidelines on the Management of Cellulitis in Adults. Guidelines on the Management of Cellulitis in Adults (2005).
4. Eron, L. J. Infection of skin and soft tissues: outcomes of a classification scheme. Clin. Infect. Dis. 31, 287 (2000).
5. NICE. Cellulitis - acute. (2016). Available at: https://cks.nice.org.uk/cellulitis-acute#!topicSummary. (Accessed: 5th March 2019)
6. Moffatt, C. J., Keeley, V., Franks, P. J., Rich, A. & Pinnington, L. L. Chronic oedema: a prevalent health care problem for UK health services. Int. Wound J. 14, 772–781 (2017).
7. David, C. V. et al. Diagnostic accuracy in patients admitted to hospitals with cellulitis. Dermatol. Online J. 17, (2011).
8. Ko, L. N. et al. Skin Surface Temperatures Measured by Thermal Imaging Aid in the Diagnosis of Cellulitis. J. Invest. Dermatol. 138, 520–526 (2018).
9. Weng, Q. Y. et al. Costs and consequences associated with misdiagnosed lower extremity cellulitis. JAMA Dermatology 153, 141–146 (2017).
10. Walsh, T. L. et al. Appropriateness of antibiotic management of uncomplicated skin and soft tissue infections in hospitalized adult patients. BMC Infect. Dis. 16, 1–8 (2016).
11. Raff, A. B. & Kroshinsky, D. Cellulitis a review. JAMA - J. Am. Med. Assoc. 316, 325–337 (2016).
12. Patel, M., Lee, S. I., Thomas, K. S. & Kai, J. The red leg dilemma: a scoping review of the challenges of diagnosing lower-limb cellulitis. Br. J. Dermatol. 0–3 (2018). doi:10.1111/bjd.17415
13. Patel, M. et al. A systematic review showing the lack of diagnostic criteria and tools developed for lower limb cellulitis. Br. J. Dermatol. (2019). doi:10.1111/bjd.17857
14. Lazzarini, L., Conti, E., Tositti, G. & de Lalla, F. Erysipelas and cellulitis: Clinical and microbiological spectrum in an Italian tertiary care hospital. J. Infect. 51, 383–389 (2005).
15. Raff, A. B. et al. 504 Dual parameter predictive model utilizing skin temperature and diffuse reflectance spectroscopy facilitates the diagnosis of cellulitis. J. Invest. Dermatol. 138, S85 (2018).
16. Raff, A. B. et al. A predictive model for diagnosis of lower extremity cellulitis: A cross-sectional study. J. Am. Acad. Dermatol. 76, 618-625.e2 (2017).
17. Ezaldein, H. H., Waldman, A., Grunseich, K. & Jubanyik, K. Risk stratification for cellulitis versus noncellulitic conditions of the lower extremity: a retrospective review of the NEW HAvUN criteria. Cutis 102, E8–E12 (2018).
18. Rast, A. C. et al. Use of procalcitonin, C-reactive protein and white blood cell count to distinguish between lower limb erysipelas and deep vein thrombosis in the emergency department: A prospective observational study. J. Dermatol. 42, 778–785 (2015).
8
19. Pallin, D. J. et al. Toward an objective diagnostic test for bacterial cellulitis. PLoS One 11, 1–15 (2016).
20. Li, D. G. et al. The ALT-70 predictive model outperforms thermal imaging for the diagnosis of lower extremity cellulitis: A prospective evaluation. J. Am. Acad. Dermatol. 79, 1076-1080.e1 (2018).
21. Clinicaltrials.gov. Handheld Infrared Thermometer to Evaluate Cellulitis (HI-TEC). Available at: https://clinicaltrials.gov/ct2/show/NCT03846635?recrs=abd&cond=skin+infection&rank=4. (Accessed: 16th July 2019)
22. Clinicaltrials.gov. Point-of-Care Ultrasound Educational Initiative for Insect Bites (USED4BUGBITE). Available at: https://clinicaltrials.gov/ct2/show/NCT03619746?recrs=abd&cond=skin+infection&rank=13. (Accessed: 16th July 2019)
23. Chira, S. & Miller, L. G. Staphylococcus aureus is the most common identified cause of cellulitis : a systematic review. Epidemiol. Infect. 138, 313–317 (2010).
24. Gunderson, C. G., Martinello, R. A. & Ct, W. H. REVIEW A systematic review of bacteremias in cellulitis and erysipelas. J. Infect. 64, 148–155 (2012).
25. Ko, L. N. et al. Clinical Usefulness of Imaging and Blood Cultures in Cellulitis Evaluation. 178, 994–995 (2018).
26. Thomas, K. S. et al. Penicillin to Prevent Recurrent Leg Cellulitis. N. Engl. J. Med. 368, 1695–1703 (2013).
27. Pallin, D. J. et al. Clinical trial: Comparative effectiveness of cephalexin plus trimethoprim-sulfamethoxazole versus cephalexin alone for treatment of uncomplicated cellulitis: A randomized controlled trial. Clin. Infect. Dis. 56, 1754–1762 (2013).
28. Quirke, M. et al. Risk factors for nonpurulent leg cellulitis: a systematic review and meta-analysis. Br. J. Dermatol. 177, 382–394 (2017).
29. Steiner, K. L. & Petri, W. A. Necrotising Fasciitis. BMJ Best Practice (2018). Available at: https://bestpractice.bmj.com/topics/en-gb/821. (Accessed: 16th July 2019)
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CONSENT FROM PATIENTS: none required.
COMPETING INTERESTS STATEMENT: We have read and understood the BMJ Group policy on declaration of interests and declare the following interests: none. COPYRIGHT STATEMENT: “The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, a worldwide licence to the Publishers and its licensees in perpetuity, in all forms, formats and media (whether known now or created in the future), to i) publish, reproduce, distribute, display and store the Contribution, ii) translate the Contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or, abstracts of the Contribution, iii) create any other derivative work(s) based on the Contribution, iv) to exploit all subsidiary rights in the Contribution, v) the inclusion of electronic links from the Contribution to third party material where-ever it may be located; and, vi) licence any third party to do any or all of the above." CONTRIBUTIONS: GE, KF, and GH all contributed to the planning, conduct, and report of the work described in this article. GH is responsible for overall content as guarantor. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
ACKNOWLEDGMENTS: The authors would like to thank Nia Roberts for performing literature searches. This work is supported by the National Institute for Health Research (NIHR) Community Healthcare MedTech and In Vitro Diagnostics Co-operative. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.
10
Boxes
What you need to know
Three novel approaches could have potential in aiding the diagnosis of cellulitis in patients
with symptoms of red legs; skin surface temperature measurement, clinical prediction
models and a visually-based computerized diagnostic decision support system.
However, the evidence is limited as the studies assessing these approaches were small and
subject to bias
Further research is needed in general practice settings on patients with undifferentiated red
leg before these technologies can be adopted in primary care.
What patients need to know
There are a number of conditions which can cause red legs. One of these is a bacterial
infection, called cellulitis. Cellulitis should be treated with antibiotics to avoid potentially
serious complications.
Emergency department studies have found that up to a third of patients seen with red legs
are given antibiotics for cellulitis when they actually have another condition for which they
are not the best treatment.
Four different kinds of tests have been evaluated to see if they can help doctors tell whether
red legs are due to cellulitis.
However these new tests have only been evaluated in small studies, and no studies were
conducted in primary care settings.
Before GPs could start using a new test, research would be needed to demonstrate that it
was able to identify cellulitis accurately in patients seen in general practice, and to show that
by using it patient outcomes were improved.
How patients were involved in the creation of this article
We shared the research question and our findings with the NIHR Community Healthcare MedTech
and IVD Cooperative’s ‘Appropriate antibiotic prescribing’ PPI group. They suggested that the focus
should be on management outside of hospital settings, and we incorporated this into our exclusion
criteria. They advised that recommendations should take account of the likely discomfort or invasive
nature of potential tests and their applicability to home monitoring of antibiotic response. We have
included these elements in our discussion.
Education into practice box. • What alternative diagnoses do you consider when a patient presents with a red leg?
If there is a lack of antibiotic response do you reconsider your diagnosis? • How could you share the decision making around antibiotic prescribing with a patient where you are not confident in the diagnosis of cellulitis or stasis dermatitis?
11
Recommendations for further research
Before any of the diagnostic strategies outlined could be considered for general practice, both
diagnostic accuracy studies and randomised controlled trials are needed in primary care settings
to address the following clinical questions:
What is the test accuracy of Procalcitonin / VCDDSS / clinical prediction models / skin surface
temperature in the diagnosis of cellulitis in patients with ‘red legs’ compared to current clinical
practice using dermatology assessment to confirm diagnosis?
What are optimal thresholds for these strategies for the diagnosis of cellulitis?
What is the impact of novel diagnostic strategies on misdiagnosis rate, antibiotic prescription,
hospitalisation rate and patient outcomes including symptom resolution and quality of life?
How could these diagnostic technologies be used to monitor antibiotic response and guide
duration of treatment?
We searched Medline, Embase and WOS from inception to July 2019 using:
Terms for skin or soft tissue infection including: cellulitis (MeSH term) OR bacterial skin
disease OR soft tissue infections OR wound infections OR skin diseases OR bacterial OR
erysipelas AND
Terms for diagnosis of skin infections including: diagnos* OR detect* OR screen* OR
test* OR
Terms for devices to aid differentiation of infectious from non-infection cases including:
point of care testing, skin AND thermometers OR thermography, skin temperature,
telethermogra*, bio* OR chem* OR electrochem* sensor OR sensors OR probe
We included studies of patients with skin or soft tissue infections, including cellulitis, erysipelas,
necrotizing fasciitis. We included studies if they reported on the detection of skin infections, or
investigated the differential of infectious and non-infectious skin.
Studies of other infections, management strategies, prognosis or severity were excluded, as
were studies of technologies which were unsuitable for primary care.
To find ongoing research we searched UK (ISRCTN), EU (clinicaltrialsregister.eu), and USA
(clinicaltrials.gov) trial registries for trials concerning diagnosis of cellulitis, erysipelas, bacterial
skin disease, skin infections, and skin inflammation.
12
Table 1. Distinguishing cellulitis from other causes of red legs. Major alternatives to consider
and diagnostic considerations, adapted from clinical guidelines.2,3,5
Unilateral causes of red leg Bilateral causes of red leg
INFE
CTI
VE
Cellulitis Acute necrotising soft tissue infection
Pain out of proportion to appearance, anaesthesia over affected skin, toxaemia, ‘woody’ hard oedema, blisters, bullae?
Deep sub-acute / chronic infection e.g. osteomyelitis.
Flare of longstanding or recurrent symptoms? Diabetic patient, overlying sinus?
Septic arthritis / bursitis
Localised around a joint? Joint movement severely limited?
Unusual pathogens
Exposure to animals, bites, water?
Bilateral true cellulitis has historically been considered to be rare11 but is increasingly common, complicating chronic dependent oedema or lymphoedema.6
History of chronic swelling or presence of oedema?
Infected ulcers (diabetic, vascular).
May have different microbiological causes from true cellulitis including potentially antibiotic resistant organisms
NO
N-I
NFE
CTI
VE
Vascular disease Deep venous thrombosis
Typically features of local and systemic inflammation will be less marked than in true cellulitis
Venous obstruction
Swelling higher in the leg? Lack of features of local and systemic inflammation?
Compartment syndrome
history of trauma, severe pain? Arterial compromise
Reactive hyperaemia may be confused with cellulitis, tissue necrosis can cause overlying inflammation. Signs of poor tissue perfusion?
Crystal arthropathies
Inflammation localised around one or more joints? joint movement severely limited? Distribution or history suggestive of gout/pseudogout?
Vascular disease Varicose / stasis eczema
The commonest misdiagnosis for cellulitis, may be mostly unilateral, itchy, brown chronic skin changes
Systemic inflammatory diseases Vasculitis, Erythema multiforme, Pyoderma gangrenosum
Multifocal or ulcerating lesions? a characteristic distribution or appearance? Features of systemic illness?
13
Table 2 Summary of 8* studies evaluating diagnostic strategies for the differential
diagnosis of cellulitis versus non-infectious skin conditions
14
Diagnostic Approach Study reference
Study population
Site of cellulitis
Setting Reference standard
Clinical question Sensitivity (%)
Specificity (%)
PPV (%)
NPV (%)
Ko 20188 32 adults with presumed cellulitis (validation cohort)
Not specified
ED General hospital physician
Cellulitis vs pseudocellulitis
Skin temperature differential of 0.47oC between the affected and
non-affected limb
100 50 85.7 100
Li 201820 67 adult patients with presumed lower limb cellulitis
Lower extremity
ED Examination by a dermatologist based on clinical impression
Cellulitis vs pseudocellulitis
Skin temperature differential of 0.47oC between the affected and
non-affected limb
87.5 38.1 75.5 57.1
Raff 201815
30 patients with presumed cellulitis
Not specified
ED Diagnosis by a dermatologist (no further details)
Cellulitis vs pseudocellulitis
No threshold specified
95.2 77.8 90.9 90.0
Raff 201716
259 adults with presumed lower limb cellulitis
Lower extremity cellulitis
ED Final discharge diagnosis
Cellulitis vs pseudocellulitis
ALT-70 score of ≥5
61.3 70.9 82.2 45.5
ALT-70 score of ≥3
96.5 29.1 74.9 79.3
Li 201820 67 adult patients with presumed lower limb cellulitis
Lower extremity
ED Examination by a dermatologist based on clinical impression
Cellulitis vs pseudocellulitis
ALT-70 score of ≥3
97.8 47.6 80.4 90.9
Ezaldein17 20 adult patients with dermatologist confirmed cellulitis and 37 with dermatitis
Not specified
Not specified
Diagnosis by a dermatologist (no further details)
Cellulitis vs stasis dermatitis
NEW HAvUN criteria 4/7
100 95.0 NR NR
David 20117
145 adult patients hospitalised with presumed cellulitis (in-patient)
Not specified
An in-patient population
NA Cellulitis vs cellulitis misdiagnoses
VCDDS more frequently included the correct alternative diagnosis amongst non-cellulitis cases than assessment by a clinician (18/28 [64%] versus 4/28 [14%], p=0.0003)
Rast 201518
48 adult ED patients (31 with erysipelas, 17 with DVT)
Lower limb
ED Clinical diagnosis by the treating physician team
Erysipelas/cellulitis versus deep vein thrombosis (DVT)
0.1 µg/L
58.1 82.4 85.7 NR
ED <0.5ng/ml (0.5 µg/L)
VC
DD
SS
Skin
su
rfac
e te
mp
erat
ure
C
linic
al p
red
icti
on
mo
del
s
15
*Li et al 2018 reported outcomes for a prediction model and skin surface temperature
ED emergency department, PPV positive predictive value, NPV negative predictive value,
VCDDSS visually based computerised diagnostic decision support system, NA not applicable,
NR not reported
Pallin 201619
21 ED patients with a diagnosis of cellulitis or dermatitis
Skin lesion in a location other than above the clavicle, or on the hand, foot, or genitals.
Confirmed microbiological testing
Cellulitis versus pseudocellulitis
0 NR NR NR
Pro
calc
ito
nin
16
Figure 1:
Image sources:
(a) https://www.flickr.com/photos/104346167@N06/35692393863
(b) http://www.pcds.org.uk/clinical-guidance/eczema-gravitational-eczema-syn.-varicose-
eczema-or-stasis-dermatitis#
(c) https://en.wikipedia.org/wiki/Thrombophlebitis
(d) https://www.consultant360.com/articles/acute-gouty-arthritis
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