Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


A Prospective Inception Cohort Study of the Clinical Presentation and Response to Treatment of Undifferentiated Spondyloarthritis Versus Ankylosing Spondylitis and Psoriatic Arthritis.

Paramarta2,  Jacqueline E., Rycke3,  Leen E. De, Ambarus3,  Carmen A., Tak1,  Paul P., Baeten2,  Dominique L.

Academic Med Ctr/Univ of Amsterdam, Amsterdam, The Netherlands
Division of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands
Division of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands

Background:

Ankylosing spondylitis (AS) and psoriatic arthritis (PsA) are the best described and studied subtypes of spondyloarthritis (SpA). A significant proportion of SpA patients, however, does not fulfil the classification criteria for AS and PsA and are at risk to be diagnosed and treated late. The aim of this study was to assess whether patients with undifferentiated SpA (USpA) are different from AS and PsA in terms of patient characteristics, disease activity and response to treatment.

Methods:

175 patients presenting on a dedicated SpA outpatient clinic fulfilling the European Spondyloarthropathy Study Group (ESSG) criteria were recruited in a prospective inception cohort. Global assessment of disease activity visual analogue scale (VAS) patient and physician, Bath Ankylosing Spondylitis Disease Activity (BASDAI), 68 swollen and tender joint count, Schober, ESR and CRP were measured every 3 months. Parametric tests were used for normally distributed data and non-parametric tests for non-normally distributed data.

Results:

The baseline demographic and clinical data are shown in Table 1.

Baseline demographics and disease activity

 USpA (n = 40)AS (n = 74)PsA (n = 45)
Median age of onset (yrs) (range)31.7 (11.2–62.1)36.5 (8.1–75.6)44.2 (20.9–68.2)**
Median disease duration (yrs) (range)1.3 (0.0–36.1)4.2 (0.0–46.8)**4.5 (0.0–29.1)**
Male sex (%)17 (42.6)43 (68.1)30 (66.7)**
Inflammatory back pain (%)35 (87.6)72 (97.3)**22 (48.9)**
Peripheral arthritis (%)25 (62.5)26 (35.1)**37 (82.2)**
HLA-B27 positive (%)17 (42.6)49 (68.1)**11 (36.5)
Sacroiliitis high grade (%)1 (2.5)74 (100.0)**10 (22.2)**
Sacroiliitis low grade (%)18 (45.0)0 (0.0)**5 (11.1)**
Positive family history for SpA (%)20 (50.0)23 (31.1)**16 (35.6)
NSAIDs (%)31 (77.5)51 (68.9)24 (53.3)**
DMARDs (%)15 (37.5)8 (10.8)**26 (57.8)**
Anti-TNF (%)4 (10.0)19 (25.7)**18 (40.0)**
VAS patient (mm) median (range)62.5 (10–100)50 (1–98)**38 (0–98)**
VAS physician (mm) median (range)51 (4–82)45 (1–90)30 (2–84)**
BASDAI median (range)5.3 (0.9–9.1)6.0 (0.3–9.2)3.2 (0.0–7.8)**
BASDAI >= 4 (%)27 (69.2)45 (63.4)20 (45.5)**
SJC (68) median (range)0 (0–8)0 (0–26)**0 (0–26)
TJC (68) median (range)1 (0–34)0 (0–16)3 (0–21)
Schober (cm) mean (SD)4.1 (1.1)3.6 (1.2)**4.2 (1.0)
Chest expansion (cm) mean (SD)4.6 (1.4)4.3 (1.5)4.5 (1.2)
ESR (mm/h) median (range)7 (1–64)10.6 (2–61)5 (1–61)
CRP (mg/l) median (range)2.0 (1.0–53.9)4.0 (1.0–38.0)2.2 (1.0–37.0)
Normally distributed: unpaired t-test not-normally distributed: Mann-Whitney; Categorical data: Chi2
* Trend (0.05<p<0.1) and ** significant difference (p<0.05) versus USpA

The cohort included 40 USpA, 74 AS and 45 PsA patients. The age of onset (median 32 years; range 11–62), disease duration (1.3 years; 0–36), and proportion of male patients (42.5%) were lower in USpA than in AS and PsA. USpA patients had more axial and less peripheral disease than PsA, but less axial and more peripheral disease than AS. The presence of HLA-B27 (43%) and either high or low grade sacroiliitis (47.5%) were less frequent in USpA than in AS. Only 25% of the USpA patients fulfilled the ASAS criteria for pre-radiological AS, although it should be noted that MRI was not systematically performed. Half of the USpA group had a positive family history. Despite the atypical presentation, the baseline disease activity (VAS patient/physician and BASDAI) was higher in USpA than in the other groups. Upon initiation of TNF blockade in patients with high disease activity, we observed a significant and sustained decrease of the disease activity in USpA, which was similar in amplitude to the response in AS and PsA (Figure 1).

Conclusion:

USpA displays an intermediate phenotype between AS and PsA, with only part of the patients representing pre-radiological axial SpA. Despite the atypical presentation and shorter disease duration, a large majority of USpA patients have high disease activity. The apparent efficacy of TNF blockers in this observational study, together with the emerging data of RCT in pre-radiological AS pleas for systematic assessment of novel treatments not only in AS and PsA but also in axial and peripheral USpA.

To cite this abstract, please use the following information:
Paramarta, Jacqueline E., Rycke, Leen E. De, Ambarus, Carmen A., Tak, Paul P., Baeten, Dominique L.; A Prospective Inception Cohort Study of the Clinical Presentation and Response to Treatment of Undifferentiated Spondyloarthritis Versus Ankylosing Spondylitis and Psoriatic Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :2272
DOI: 10.1002/art.30035

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