Classification criteria for spondyloarthropathies

Abstract

Spondyloarthropathies (SpA) are a group of inflammatory arthritis which consist of ankylosing spondylitis (AS), reactive arthritis, arthritis/spondylitis associated with psoriasis (PsA), and arthritis/spondylitis associated with inflammatory bowel diseases. It is now more important than ever to diagnose and treat SpA early. New therapeutic agents including blockers of tumor necrosis factor have yielded tremendous responses not only in advanced disease but also in the early stages of the disease. Sacroiliitis on conventional radiography is the result of structural changes which may appear late in the disease process. However, magnetic resonance imaging (MRI) can visualize active inflammation at sacroiliac joints and spine in recent onset disease. The modified New York criteria, the European Spondyloarthropathy Study Group criteria and the Amor criteria do not include advanced imaging techniques like MRI which is very sensitive to the early Inflammatory changes. Assessment of SpondyloArthritis international Society has defined MRI methods for the assessment of sacroiliac joints and spine, criteria for inflammatory back pain and developed new criteria for classification of axial and peripheral spondyloarthritis. These new criteria are intended to be used for patients with SpA at the very early stage of their disease. Also, classification of psoriatic arthritis study group developed criteria for the classification of PsA. The widespread use of these criteria in clinical trials will provide evidence for a better definition of early disease and recognize many patients who may further develop classical AS or PsA. These efforts will guide therapeutic trials of potent drugs like biological agents in the early stage of these diseases.

Full text

Classication criteria for spondyloarthropathies
Ozgur Akgul, Salih Ozgocmen
Ozgur Akgul, Salih Ozgocmen,
Division of Rheumatology,
Department of Physical Medicine and Rehabilitation, Erciyes
University, Gevher Nesibe Hospital, 38039 Kayseri, Turkey
Author contributions:
Akgul O and Ozgocmen S collectively
reviewed the literature and drafted the manuscript.
Correspondence to: Salih Ozgocmen, Professor,
Division of
Rheumatology, Department of Physical Medicine and Rehabilita-
tion, Erciyes University, Gevher Nesibe Hospital, FTR AD, Ro-
matoloji BD, 38039 Kayseri, Turkey. sozgocmen@hotmail.com
Telephone:
+90-352-4374901
Fax:
+90-352-2353605
Received:
July 29, 2011
Revised:
October 20, 2011
Accepted:
November 29, 2011
Published online:
December 18, 2011
Abstract
Spondyloarthropathies (SpA) are a group of inamma-
tory arthritis which consist of ankylosing spondylitis
(AS), reactive arthritis, arthritis/spondylitis associated
with psoriasis (PsA), and arthritis/spondylitis associ-
ated with inammatory bowel diseases. It is now more
important than ever to diagnose and treat SpA early.
New therapeutic agents including blockers of tumor
necrosis factor have yielded tremendous responses not
only in advanced disease but also in the early stages
of the disease. Sacroiliitis on conventional radiography
is the result of structural changes which may appear
late in the disease process. However, magnetic reso-
nance imaging (MRI) can visualize active inammation
at sacroiliac joints and spine in recent onset disease.
The modied New York criteria, the European Spondy-
loarthropathy Study Group criteria and the Amor cri-
teria do not include advanced imaging techniques like
MRI which is very sensitive to the early Inammatory
changes. Assessment of SpondyloArthritis international
Society has defined MRI methods for the assessment
of sacroiliac joints and spine, criteria for inammatory
back pain and developed new criteria for classication
of axial and peripheral spondyloarthritis. These new
criteria are intended to be used for patients with SpA at
the very early stage of their disease. Also, classication
of psoriatic arthritis study group developed criteria for
the classication of PsA. The widespread use of these
criteria in clinical trials will provide evidence for a better
denition of early disease and recognize many patients
who may further develop classical AS or PsA. These
efforts will guide therapeutic trials of potent drugs like
biological agents in the early stage of these diseases.
© 2011 Baishideng. All rights reserved.
Key words:
Classification criteria; Spondyloarthritis;
Psoriatic arthritis; Ankylosing spondylitis
Peer reviewers:
Thomas J Kishen, Dr., Spine Service,
Sparsh-Hospital for Advanced Surgeries 146, Infantry Road,
Bangalore 560001, Karnataka, India; Kanji Mori, MD, PhD,
Assistant Professor, Department of Orthopaedics Surgery, Shiga
University of Medical Science, Tsukinowa-cho, Seta, Otsu
520-2192, Japan; Wen-Bao Wang, MD, Department of Surgery,
Harlem Hospital, 106 Fort Washington Avenue, Apt 3H, New
York, NY 10032, United States
Akgul O, Ozgocmen S. Classication criteria for spondyloarthrop-
athies. World J Orthop 2011; 2(12): 107-115 Available from:
URL: http://www.wjgnet.com/2218-5836/full/v2/i12/107.htm
DOI: http://dx.doi.org/10.5312/wjo.v2.i12.107
INTRODUCTION
Spondyloarthropathies (SpA) are a group of inamma-
tory arthritis that consist of ankylosing spondylitis (AS),
reactive arthritis, arthritis/spondylitis associated with
psoriasis (PsA) and arthritis/spondylitis associated with
inflammatory bowel diseases (IBD). The association
with human leukocyte antigen (HLA)-B27, peripheral
joint involvement predominantly of the lower extremi-
ties, sacroiliitis, spondylitis, enthesitis, dactylitis, uveitis,
enteric mucosal lesions and skin lesions are the shared
manifestations of the diseases
[1,2]
. Categorization of an
individual patient into a subset of SpA can be difcult
EDITORIAL
Online Submissions: http://www.wjgnet.com/2218-5836ofce
wjo@wjgnet.com
doi:10.5312/wjo.v2.i12.107
World J Orthop 2011 December 18; 2(12): 107-115
ISSN 2218-5836 (online)
© 2011 Baishideng. All rights reserved.
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Akgul O
et al
. Classication criteria for spondyloarthropathies
due to the lack of well-defined criteria for the diagno-
sis
[3]
. The newly developed Assessment of SpondyloAr-
thritis International Society (ASAS) classication criteria
proposes to classify the SpA according to leading clinical
manifestations; predominantly axial or predominantly
peripheral, with or without associated psoriasis, IBD or
preceding infection
[4,5]
.
The new developments in the clinical and scientific
aspects of SpA were pursued by the need for new strate-
gies for denition of early diagnosis and outcome criteria
for clinical studies. There is a long delay, approximately 5-6
years, between the rst occurrence of the SpA symptoms
and the diagnosis of the disease especially for female,
juvenile onset or HLA-B27 negative patients
[6,7]
. The
major reason for this delay may be the low awareness of
AS among the physicians as well as a lack of well dened
criteria for identifying patients with inflammatory back
pain (IBP) from chronic low back pain of mechanical
origin. Relatively late appearance of sacroiliitis on plain
radiographs, due to insidious nature of AS, is another
reason for delay. Recent developments demonstrated that
inammation of sacroiliac joints could be well visualized
by magnetic resonance imaging (MRI) long before than
radiographic changes take place
[8]
.
WHAT ARE CLASSIFICATION CRITERIA?
Classication criteria serve to dene disease groups for
clinical and epidemiological studies
[9]
. These sets of clas-
sication criteria combine different types of information
like symptoms, signs, laboratory findings, imaging, ge-
netic factors and etiological agents.
Classification criteria should not contain too many
false positives and should have high specicity. Because
of the inverse relationship, it has low sensitivity. In clini-
cal studies, classification criteria provide homogeneous
patient groups which thus enable comparisons. On the
other hand, diagnostic criteria should have high sensitiv-
ity in order to make a correct diagnosis; this means that
it may contain false positives and may have low specic-
ity. Most of the rheumatic diseases do not have unique
or specific diagnostic tests and classification criteria
have been developed to identify homogeneous patient
populations for clinical trials. It should be noted that
most of the criteria sets in rheumatology have been de-
veloped as classication criteria for clinical research but
unfortunately are widely used as diagnostic tools in daily
practice. This is, for example, the case with the formerly
the American Rheumatism Association criteria (for the
classication of rheumatoid arthritis) and the European
Spondylarthropathy Study Group (ESSG) preliminary
criteria for the classication of spondyloarthropathies
[10]
.
Inammatory back pain
Inflammatory back pain is the leading symptom of the
SpA and mirrors inammation of sacroiliac joints, spine
and spinal entheses. However its value for the diagnosis,
classification and screening in primary care settings is
not well recognized. Clinical history has been proposed
as a screening test to identify patients with SpA among
those who have chronic back pain
[11]
.
In general, criteria
for IBP were derived from studies comparing patients
with AS and patients with back pain of other etiologies
and from studies based on expert opinion. Although IBP
is considered as the foremost clinical symptom for axial
SpA, its sensitivity and specicity with respect to diagno-
sis of axial SpA does not exceed 80%
[12]
.
Calin
et al
[13]
examined 42 patients with AS and 24
patients with other origin of back pain for 5 features of
back pain: (1) insidious onset; (2) age at onset < 40 years;
(3) duration of back pain
≥
3 mo; (4) associated with
morning stiffness; and (5) improvement with exercise. IBP
was considered in the presence of 4 of 5 features, and
these were the first criteria for IBP
(Table 1). However,
Calin’s criteria had some limitations. Duration of morn-
ing stiffness was later reported by Gran; a duration more
than 30 min is associated with AS, and has 64% sensitivity
and 58% specicity
[14]
.
In the original study, Calin’s criteria
have 95% specificity and 76% sensitivity but the subse-
quent studies showed low sensitivity and specificity
[14,15]
.
Adding a single criterion “getting out of the bed at night”
improved the sensitivity of these criteria
[14]
.
Modied New York Criteria (mNY) for AS integrated
features of the Calin’s criteria made the definition of
back pain in patients with AS: low back pain and stiff-
ness more than 3 mo, improving with exercise but is not
relieved by rest
[16]
. Various combinations of IBP features
were evaluated in 101 patients with AS and 112 patients
with mechanical low back pain by Rudwaleit
et al
[11]
. Clini-
cal features of back pain were: (1) morning stiffness >
30 min; (2) age of onset; (3) no improvement by rest; (4)
awakening because of the pain in the second half of the
night only; (5) alternating buttock pain; and (6) duration
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Calin’s criteria
for IBP
Berlin criteria for IBP ASAS IBP criteria mnemonic
for criteria “iPAIN”
Age at onset
< 40 yr
Morning stiffness of
> 30 min duration
Insidious onset
Duration of back
pain > 3 mo
Improvement in back
pain with exercise but
not with rest
Pain at night
(with improvement upon
getting up)
Insidious onset
Morning
stiffness
Nocturnal awakening
(second half of the night
only)
Age at onset < 40 yr
Improvement
with exercise
Alternating buttock pain Improvement with exercise
No improvement with rest
Requires the
presence of four
of ve criteria
The sensitivity is 70%
specicity 81% if two
of the four criteria are
fullled
The sensitivity is 77.0% and
specicity 91.7% if at least
four out of ve criteria are
fullled
Table 1 Inammatory back pain criteria sets and mnemonic
for assessment of spondyloarthritis international society
criteria
[11-13,17]
IBP: Inflammatory back pain; ASAS: Assessment of spondyloarthritis
international society; iPAIN: Inammatory PAIN.

of back pain. None of the single parameters differenti-
ated AS from MLBP. Based on a good balance between
sensitivity, specificity and feasibility the Berlin criteria
were proposed with 70% sensitivity and 81% specicity
(Table 1).
In 2009, thirteen internationally well-known rheuma-
tologists, considered as experts in AS/SpA and members
of ASAS, participated in the development of new clas-
sification criteria for IBP. They presented new ASAS
IBP criteria without major differences from formerly
established IBP criteria (Table 1). ASAS IBP criteria have
77.0% sensitivity and 91.7% specicity when at least four
out of five parameters are present. Calin criteria had a
higher sensitivity but a lower specificity. Berlin criteria
had a lower sensitivity and a higher specificity with re-
spect to newly developed criteria
[12]
. Mnemonic for ASAS
IBP criteria (iPAIN: Inflammatory PAIN) has been re-
cently published
[17]
(Table 1).
Imaging
Imaging of the sacroiliac joints and the spine has an
important role in the diagnosis, classication and moni-
toring for patients with SpA. Sacroiliitis on conventional
radiography became an important diagnosis in AS and
was given an outstanding role in the development of
classication criteria in 1961 and mNY criteria in 1984
(Table 2) Usually bilateral grade
≥
2 or unilateral grade
≥
3 sacroiliitis are considered critical for the diagno-
sis of AS
[16]
.
However, radiographic sacroiliitis reflects
structural changes which may appear late in the disease
process at least in a subset of patients
[18]
. Thus, it has
low specicity especially for patients at the early stages
of the disease.
Magnetic resonance imaging can visualize active in-
flammation at sacroiliac joints and spine in established
or in early pre-radiological axial disease, regardless of
disease stage
[19]
. The mNY, ESSG criteria and the Amor
criteria do not contain MRI as an imaging tool. Actually,
MRI of the sacroiliac joints was dened however it was
not well established or standardized, when these criteria
were developed.
ASAS classication criteria for axial SpA have imag-
ing and clinical arms. The imaging arm includes either
sacroiliitis on conventional radiography or sacroiliitis on
MRI, which is highly important for recognition of pre-
radiographic changes in early SpA
[4]
.
Regarding spondylitis, which may also occur before
sacroiliitis, a denition of a “positive MRI” for the spinal
inammation is also needed
[20]
. However, there is insuf-
ficient data for the use of spinal MRI and little is yet
known about the specicity of spinal features in the axial
SpA
[21]
.
Active inflammatory lesions such as bone marrow
edema/osteitis, synovitis, enthesitis and capsulitis associ-
ated with SpA can be detected by MRI. Also structural
damage such as sclerosis, erosions, fat deposition and an-
kylosis can be detected by MRI. ASAS/OMERACT im-
aging group dened minimum amount of bone marrow
edema (one lesion at least two adjacent slices or more
than one lesion at least one slice) which is required for
the denitive diagnosis sacroiliitis
[22]
. Figure 1A-D repre-
sents a normal radiograph of the pelvis and early changes
on sacroiliac MRI of a male patient at the early stages of
the disease (pre-radiographic stage). Figure 2A-C repre-
sents inflammatory changes and structural damage on
spinal MRI.
HLA B-27
HLA B-27 positivity is extremely relevant to the early di-
agnosis of SpA. Five to 10% of the population are HLA
B-27 positive and in patients with AS and SpA the posi-
tivity of HLA B-27 changes to 70% to 95% and nearly
70%, respectively
[23]
.
SPECTRUM OF
SPONDYLOARTHROPATHIES
Ankylosing spondylitis
Ankylosing spondylitis is the most common and most
typical form of SpA. It is two to three times more com-
mon in men than women. Ankylosing spondylitis usu-
ally begins with back pain and stiffness at a young age
but various presentations, such as peripheral arthritis
and enthesopathy may antedate back symptoms in some
patients. Late onset after the age of 45 is uncommon in
AS however some patients may reasonably be diagnosed
late. Inammatory low back pain is one of the presenting
features but not solely specic to AS. History of uveitis,
positive family history for AS, impaired spinal mobility or
chest expansion supports the diagnosis
[1]
.
Axial involvement is one of the characteristics of the
disease and 90% of patients have radiographic sacroiliitis
during the course of the disease. The rst classication
criteria for AS were proposed in 1963 at the European
Congress of Rheumatology in Rome, based on the clini-
cal experience of rheumatologists. Later in 1966, thoracic
pain and uveitis were removed from the criteria set be-
cause of low specicity and low sensitivity. This preceded
the framework of New York criteria which was modied
in 1984 by using inammatory back pain components re-
ported by Calin
et al
[13]
. A patient can be classied as hav-
ing denite AS if at least one clinical criterion (IBP, limi-
tation of lumbar spine or limitation of chest expansion)
plus radiologic criterion (bilaterally grade 2 or unilateral
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Low back pain for at least 3 mo duration improved by exercise and not
relieved by rest
Limitation of lumbar spine motion in sagittal and frontal planes
Chest expansion decreased relative to normal values for age and sex
Unilateral sacroiliitis grade 3–4
Bilateral sacroiliitis grade 2–4
Denite ankylosing spondylitis if (4a or 4b) and any clinical criterion
(1–3)
Table 2 Modified New York criteria for ankylosing
spondylitis
[16]
Akgul O
et al
. Classication criteria for spondyloarthropathies

grade 3-4 sacroiliitis) are fullled
[16]
. These classication
criteria are inevitably used for the diagnosis of AS by
most clinicians (Table 2).
All these criteria included presence of spinal/thoracic
pain, restriction of spinal mobility and radiological sacroi-
liitis. Restriction of spinal mobility and radiological sac-
roiliitis may reect structural damage and spinal/thoracic
pain may reect active inammation and structural dam-
age as well. It is obvious that these criteria do not perform
well in patients with early/pre-radiographic phase of AS.
Axial spondyloarthritis
As mentioned above, sacroiliitis on plain radiographs
takes years from the onset IBP and the symptoms of IBP
alone are not diagnostic in many patients.
Berlin criteria were developed to assist physicians for
early diagnosis of SpA. In this criterion set, the clini-
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B
D
Figure 1 Normal radiograph of the pelvis and early changes on sacroiliac
magnetic resonance imaging of a male patient at the early stages of the
disease at the pre-radiographic stage. A: Thirty-ve year old male, normal
anterior posterior pelvis radiograph; B: T1-weighted Fast Spin Echo semi-
oblique coronal scans of the sacroiliac joints; C: T2-weighted fat suppressed
images shows bone edema at both sacral and iliac bones; D: T1-weighted
post-contrast image shows enhancement of the contrast media revealing acute
inammation.
A
C
Figure 2 Inflammatory changes and structural damage on spinal mag-
netic resonance imaging. A: T1-weighted fast spin echo sagittal magnetic
resonance scan of the lumbar spine shows hypointense lesion on end plates
of thoracic 11 and 12 vertebrae; B: T2-weighted fat suppressed sagittal image
shows hyperintense signals at the lesion and also at the upper anterior of the
L3 and lower anterior of L2 vertebra; C: T1-weighted post-contrast images
shows enhancement of the contrast media at the borders of the lesion revealing
acute spondylodisciitis.
Akgul O
et al
. Classication criteria for spondyloarthropathies
B B
A
C

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cal, laboratory (HLA B-27) and imaging (MRI of sac-
roiliac joints) features were included. The diagnosis of
recent-onset axial SpA (pre-radiographic SpA) can be
established in patients who have clinical features without
radiographic changes but sacroiliitis on MRI. This study
also analyzed the role of MRI as a diagnostic tool
[24]
.
The performance of Berlin criteria has been tested and
showed that the diagnostic capacity in patients with axial
undifferentiated SpA in the Chinese population was simi-
lar to ESSG and Amor criteria
[25]
.
In 2004, ASAS decided to improve current SpA cri-
teria particularly to apply to patients in the early disease
stages. It was proposed that SpA patients with predomi-
nantly axial symptoms but without radiographic sacroili-
itis could be considered as patients with pre-radiographic
phase of AS. The need for an early diagnosis in all pa-
tients with AS and axial SpA is put forward
[26]
.
In 2009, ASAS developed two candidate criteria sets
for classication of axial SpA that include patients with-
out denite radiographic sacroiliitis
[27]
. The candidate sets
were tested in the entire cohort of 649 patients from 25
centers in 16 countries. The new criteria consisted of a
‘clinical arm’ and ‘imaging arm’ (Figure 3).
The entire set
had 82.9% sensitivity and 84.4% specificity and for the
‘imaging arm’ alone sensitivity was 66.2% and specicity
was 97.3%. The specicity of the new criteria was much
better than ESSG criteria modied by adding MRI and
slightly better than Amor criteria modified by adding
MRI
[27]
. The sensitivity is almost the same for the three
criteria set. ASAS criteria are quite simple and easily ap-
plicable in daily clinical practice and a mnemonic is pro-
posed to facilitate its use
[17]
(Figure 3).
Peripheral spondyloarthritis
After the development of ASAS criteria for axial SpA,
ASAS experts developed criteria for patients with SpA
with predominant peripheral manifestations and com-
pared these with ESSG and Amor criteria which were
generated for the entire SpA group including peripheral
SpA
[5]
. Patients with peripheral manifestations including
peripheral arthritis, dactylitis and enthesitis and without
back pain were included. The sensitivity of the criteria was
77.8% and the specicity was 82.2% (Figure 4). The new
ASAS classication criteria for peripheral arthritis would
seem to perform better than ESSG and Amor criteria.
Spondyloarthritis in general
Spondyloarthropathies were formally classied in Amor
criteria in 1990. Amor’s criteria are a list of signs based
on a scoring system of laboratory, radiologic and clini-
cal features and do not require an entry criterion
[28]
.
The signs in the criteria contribute 1 point, 2 points or 3
points; a score of 6 or more classies a patient as having
SpA. Although sacroiliitis is not mandatory for the diag-
nosis of SpA, it had the highest score (3 points) and is
considered to be very specic for SpA
(Table 3).
ESSG criteria were proposed in 1991. In ESSG crite-
ria IBP and/or peripheral arthritis are required as entry
criteria. Patients with at least one entry criterion and one
minor criterion are classified as having SpA
[29]
(Figure
5). The aim of ESSG criteria is to include undifferenti-
ated SpA which was not been proposed in Amor criteria.
Both of these criteria were considered to be helpful for
the diagnosis of SpA and had a broader denition of the
spectrum however, they have low sensitivity particularly
for the early diagnosis of SpA. For example, some of the
leading symptoms like uveitis may be omitted by ESSG
criteria but captured by Amor criteria.
Both sets of criteria were evaluated in a multicenter
cross-sectional study including 124 patients with SpA
and 1964 controls. Overall performance of both sets was
similar and the performance was better in patients with
a denite diagnosis
[30]
. These criteria were evaluated for a
Turkish population in 157 patients with SpA and in 127
patients with various rheumatic diseases. Results showed
that both criteria had a similar value for classication of
Arthritis or enthesitis or dactylitis
Patient with peripheral manifestations only
(if back pain is actually present the axial SpA criteria should be applied)
Plus
≥
2 of the remaining
Arthritis
Enthesitis
Dactylitis
IBP in the past
Positive family history for SpA
Plus
≥
1 of
Psoriasis
Inammatory bowel disease
Preceding infection
HLA-B27
Uveitis
Sacroiliitis on imaging
Figure 4 Assessment in spondyloarthritis international society classica-
tion criteria for peripheral spondyloarthritis or spondyloarthritis in gen-
eral
[5]
. SpA: Spondyloarthropathies; IBP: Inammatory back pain; HLA: Human
leukocyte antigen.
Sacroiliitis on
imaging
1
plus
≥
1 SpA feature
HLA-B27 plus
≥
2 other SpA
features
2
SpA features SPINEACHE
Sausage digit (dactylitis)
Psoriasis- Positive family history of SpA
Inammatory back pain
NSAID good response
Enthesitis (heel)
Arthritis
Crohn’s/Colitis disease-elevated CRP
HLA-B27
Eye (uveitis)
Or
Figure 3 Assessment in SpondyloArthritis international Society
classification criteria for axial spondyloarthritis and mnemonic for
assessment of spondyloarthritis international society classification
criteria
[4,17]
.
1
Sacroiliitis on imaging active (acute) inflammation on magnetic
resonance imaging highly suggestive of sacroiliitis associated with SpA or
definitive radiographic sacroiliitis according to modified New York criteria;
2
Elevated CRP is considered a SpA feature in the context of chronic back pain.
SpA: Spondyloarthropathies; CRP: C-reactive protein; NSAID: Nonsteroidal
antiinammatory drugs; HLA: Human leukocyte antigen.
Akgul O
et al
. Classication criteria for spondyloarthropathies

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SpA and were comparable in terms of specificity and
sensitivity
[31]
.
In a newly published study, performance of ESSG
criteria, ASAS criteria and mNY criteria were compared
in patients with SpA. The ASAS criteria had the highest
sensitivity compared to ESSG criteria and mNY criteria
98.4%, 83.6% and 71.9%, respectively
[32]
. In other stud-
ies of different ethnicities, lower sensitivity for mNY but
similar sensitivity for ESSG was reported
[33-35]
.
Recently, the French Society of Rheumatology pre-
sented the DESIR cohort. Patients were recruited if they
had IBP more than 3 mo and less than 3 years. A total of
708 patients were recruited and the mNY criteria, Amor
criteria, ESSG criteria and axial ASAS criteria were ful-
lled by 26%,77%, 76% and 67% at entry, respectively
[36]
.
The diagnostic accuracy of the ESSG criteria, Amor
criteria and the combination of them was analyzed in 24
patients who were misdiagnosed as SpA. The ratio of the
misdiagnosed patients who fullled ESSG criteria, Amor
criteria and combination were 45.8%, 16.7%, 16.7%, re-
spectively. This study suggests that ESSG criteria may not
be absolutely secure for the diagnosis of SpA
[37]
.
Performance of mNY criteria, ESSG criteria, Amor
criteria and Berlin criteria in patients with IBP of a maxi-
mum of 2 years duration was evaluated. Fourteen of the
68 patients had AS according to mNY and all fulfilled
three of SpA criteria sets. The highest classication rate
was found with the ESSG criteria (84%), followed by the
Amor criteria (71%) and the Berlin criteria (65%). The
ESSG criteria were the most sensitive and the mNY crite-
ria for AS appeared to be most specic sets of criteria
[38]
.
Psoriatic arthritis
Psoriatic arthritis (PsA) is defined as an inflammatory
arthritis associated with cutaneous psoriasis. Patients may
have peripheral arthritis (oligoarthritis or polyarthritis),
enthesitis, dactylitis or sacroiliitis/spondylitis
[39]
.
At the be-
ginning of the century PsA was thought to coincidentally
occur with rheumatoid arthritis (RA) and psoriasis. Psori-
atic arthritis was adopted as a distinct disease for the rst
time in 1964. The distinction between RA and PsA was
made based on the clinical and radiological features
[40]
.
In 1973 Moll and Wright
[41]
reported a proposal for
the classication of PsA. When a patient with psoriasis
has inammatory arthritis and is negative for rheumatoid
factor (RF) PsA can be classied in ve distinct clinical
subsets as: (1)
oligoarticular asymmetric arthritis (< 5
tender and swollen joints); (2)
polyarticular arthritis; (3)
distal interphalangeal joint predominant; (4) spondylitis
predominant; and (5) arthritis mutilans predominant.
Over the passing years minor modications have been
made on these criteria. Gladman
et al
[42]
suggested that
there is no need to insist on seronegativity for RF, since
it can be positive in healthy subjects and in their series,
12% of cases were RF (+) even when the patients who
had a characteristic sign of RA, like rheumatoid nodules
and extra-articular manifestations were excluded. It is
also possible to differentiate seronegative RA from PsA
by using other antibodies, anti-cyclic citrullinated peptide
which has much higher specicity than RF for the diag-
nosis of RA.
Psoriasis is a common disease affecting nearly 1%-2%
of the population. In some forms of arthritis coinciden-
tal psoriasis may also occur. Psoriasis may precede, si-
Amor criteria
Clinical symptoms or history of scoring Points
Lumbar or dorsal pain at night or morning stiffness of
lumbar or dorsal pain
1
Asymmetrical oligoarthritis 2
Buttock pain 1
If alternate buttock pain 2
Sausage like toe or digit 2
Heel pain or other well-dened enthesopathy 2
Iritis 1
Nongonococcal urethritis or cervicitis within 1 mo before
the onset of arthritis
1
Acute diarrhea within one month before the 1 mo onset
of arthritis
1
Psoriasis, balanitis, or inammatory bowel disease
(ulcerative colitis or Crohn’s disease)
2
Radiological ndings
Sacroiliitis (bilateral grade 2 or unilateral grade 3) 3
Genetic background
Presence of HLA-B27 and/or family history of ankylosing
spondylitis, reactive arthritis, uveitis, psoriasis, or
inammatory bowel disease
2
Response to treatment
Clear-cut improvement within 48 h after NSAIDs intake or
rapid relapse of the pain after their discontinuation
2
A patient is considered as suffering from a pondyloarthropathy
if the sum is
≥
6
Table 3 Amor criteria for the classication of spondyloarthro
pathies
[28]
NSAID: Nonsterodial anti-inflammatory drug; HLA: Human leukocyte
antigen
.
Inammatory spinal pain or synovitis
(asymmetric, predominantly in lower extremities)
Plus one of the following
Family history: rst- or second-degree relatives with ankylosing spondylitis,
psoriasis, acute iritis, reactive arthritis, or inammatory bowel disease
Past or present psoriasis, diagnosed by a physician
Past or present ulcerative colitis or Crohn’s disease, diagnosed by a
physician and conrmed by radiography or endoscopy
Past or present pain alternating between the two buttocks
Past or present spontaneous pain or tenderness at examination of the site
of the insertion—the Achilles tendon or plantar fascia (enthesitis)
Episode of diarrhea occurring within 1 mo before onset of arthritis
Nongonococcal urethritis or cervicitis occurring within 1 mo before onset
of arthritis
Bilateral grade 2–4 sacroiliitis or unilateral grade 3 or 4 sacroiliitis [grades
are 0: normal; 1: possible; 2: minimal; 3: moderate; 4: completely fused.
(ankylosed)]
Figure 5 European Spondyloarthropathy Study Group Criteria for the
classication of spondyloarthropathies
[29]
.
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113 December 18, 2011
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multaneously occur or appear many years after the onset
of arthritis. In latter cases patients may be misdiagnosed
with other types of arthritis like seronegative RA or reac-
tive arthritis; however, positive family history for psoria-
sis may be helpful in these cases. Patients with arthritis
should be carefully examined for existence of “hidden”
psoriatic lesions which may be located under the breasts,
around the umbilicus or anus, over the hairline, nasal cleft
or nails
[41]
.
Patients with PsA tend to have inflammatory axial
involvement similar to AS. There are several differences
from the classical AS
[41]
:
(1) asymmetrical sacroiliitis; (2)
non-marginal syndesmophytes; (3) asymmetrical syndes-
mophytes; and (4) more frequent involvement of the cer-
vical spine.
Bennett thought that Moll and Wright criteria tend to
over diagnosing PsA and suggested new criteria in 1979.
In these new set of criteria, clinical and radiological fea-
tures were combined with synovial uid analysis and his-
tology. These criteria have not been widely used in pro-
spective studies since synovial uid analysis and histology
are not practical. Psoriatic skin or nail involvement plus
either peripheral joint or axial disease were required
[41]
.
Simplification of Bennett’s criteria has been made by
Vasey and Espinoza
[42]
.
ESSG criteria were also valid for PsA. For the first
time skin or nail involvement was not mandatory in these
criteria. Cases in which arthritis precedes psoriasis are
well recognized and family history of psoriasis can help
the diagnosis
[29]
.
A denition of PsA based on enthesopathy has been
proposed by McGonagle
et al
[43]
.
There is a significant
problem with these criteria because of MRI require-
ments. It is not practical to use MRI in epidemiological
research. MRI appearance shows both features of enthe-
sopathy and synovitis and so the discrimination capac-
ity would be markedly attenuated in established disease.
Fournie
et al
[44]
proposed criteria from actual patient data
to diagnose PsA which requires a score of 11 points for
diagnosis.
There are few studies that compare different crite-
ria for the diagnosis of PsA. A study which compared
performance of the criteria revealed that the sensitivity
of Vasey and Espinoza, McGonagle and Gladman were
99% whereas Bennett and ESSG criteria were signicant-
ly less sensitive. The specicity of the criteria was as high
as 93% and 99%, and there were no statistically signi-
cant difference between criteria. Fournie criteria were the
most difcult to use and Vasey and Espinoza, and Moll
and Wright were the easiest. Vasey and Espinoza, Glad-
man or McGonagle are the most accurate and feasible in
distinguishing RA from PsA
[45]
.
The classification of psoriatic arthritis (CASPAR)
study group is an international group of investigators,
all of whom have records of research in PsA. They pro-
posed new data-driven classication criteria for PsA and
collected prospective clinical and radiological data of 588
patients with PsA and 536 patients with other inamma-
tory arthritis, at least half of them with RA (Figure 6).
The performance of the new criteria were also compared
to other existing data
[46]
. The sensitivity and specicity of
the CASPAR criteria in the original study were 91.4% and
98.7%, respectively. These criteria were more specic but
less sensitive than Vasey and Espinoza criteria.
The main limitation of the CASPAR criteria is the ap-
plicability to recent-onset disease. Very high sensitivity of
CASPAR criteria in early and late PsA was also demon-
strated in a study
[47]
. This study analyzed patients referred
to a special tertiary referral clinic and did not have a
control population. It seems likely that only patients with
secure clinical diagnoses are referred and enrolled into
this clinic, possibly leading to an overestimation of the
sensitivity of the criteria
[48]
.
Family history of psoriasis is the advantage of CAS-
PAR criteria over Vasey and Espinoza as well as Moll and
Wright criteria. It is also possible to make a diagnosis of
PsA for patients who are RF positive and have polyar-
ticular symmetric arthritis. The CASPAR, as a simple and
user-friendly criteria set, has high potential to be intro-
duced as the universal classication criteria for PsA
[42]
.
CONCLUSION
Chronic low back pain is a common and important prob-
lem and patients with this disorder are seen by a variety
of specialists including rheumatologists, orthopedic sur-
geons, physiatrists, family physicians etc. Inflammatory
Inammatory articular disease (joint, spine or enthesal) and 3 points of fol-
lowing criteria)
Evidence of current psoriasis
1
, a personal history of psoriasis, or a family
history of psoriasis
Current psoriasis is dened as psoriatic skin or scalp disease present to
day as judged by a rheumatologist or dermatologist
A personal history of psoriasis is dened as a history of psoriasis that
may be obtained from a patient, family physician, dermatologist,
rheumatologist, or other qualied health care provider
A family history of psoriasis is dened as a history of psoriasis in a
rst- or second-degree relative according to patient report)
Typical psoriatic nail dystrophy including onycholysis, pitting, and
hyper keratosis observed on current physical examination
A negative test result for the presence of rheumatoid factor by any
method except latex but preferably by enzyme-linked immunosorbent
assay or nephelometry, according to the local laboratory reference range
Either current dactylitis, dened as swelling of an entire digit, or a history
of dactylitis recorded by a rheumatologist
Radiographic evidence of juxtaarticular new bone formation, appearing
as ill-dened ossication near joint margins (but excluding osteophyte
formation) on plain radiographs of the hand or foot
Figure 6 Classication of psoriatic arthritis study group criteria for the
classication of psoriatic arthritis
[46]
.
1
Current psoriasis is assigned a score
of 2; all other features are assigned a score of 1.
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. Classication criteria for spondyloarthropathies

114 December 18, 2011
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low back pain is usually the leading symptom of spondy-
loarthropathies and physicians should always be aware.
For a correct diagnosis IBP should be differentiated from
mechanical back pain. A detailed screening of signs and
symptoms in terms of insidious onset, morning stiffness,
pain at night, improvement with exercise and favorable
response to NSAIDs may ease the discrimination. Other
common features of SpA like dactylitis, enthesitis, ar-
thritis and history of preceding infections should also
be checked. Imaging has an important role in the early
diagnosis of SpA and the very early phase of sacroiliitis
or spondylitis could be detected by documenting active
inammatory lesions like bone marrow edema, enthesitis,
capsulitis or synovitis on MRI. HLA B-27 positivity is ex-
tremely relevant to the early diagnosis of SpA.
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S- Editor
Yang XC
L- Editor
Roemmele A
E- Editor
Yang XC
Akgul O
et al
. Classication criteria for spondyloarthropathies