Seronegative spondyloarthropathy-related sacroiliitis: Differencial diagnosis between infectious sacroiliitis and spondyloarthritis, where the inflammation in the sacroiliac joint starts

Material and methods: Highly selective group of patients with SA was followed in the period of one year: group of 23 patients (pts) with unconvincing radiographic changes for SA from 1-2° and group of 21 pts without radiographic changes i.e. 0°. Beside SA, both groups fulfi lled at least another from the listed conditions: 1.oligoarthritis; 2. enthesitis; 3. iridocyclitis; 4. positive family history for SA; 5. positive antigen HLA-B27 and 6. Elevated ESR > 30mm/h.


Matheria and methods
In patients included in this study disease diagnosiswas They were dermatologically tested, including examination of psoriatic changes, nails, psoriatic areas as well as an index for disease activity (PASI) and evaluation of peripheral and axial joints. The diagnosis of oligoarthritis was made when <5 joints were involved, polyarthritis when >5 joints were involved.
Diagnosis of symmetric arthritis was made when there was bilateral involvement of> 50% of joints.
Mean duration in months from the beginning of disease is 7,27 (± 6,12). Patients did not take any previous medication that would modify the course of the disease like sulphasalazine, methotrexate, lefl unamide. The samples were collected in the period of one year. In the group of 23 pts with without radiographic changes for SA we expected to fi nd authentic cases of SA in the early stages of disease.

Including criteria
In this study were included newly diagnosed patients suffering from sacroiliitis, aged 18-45 years, previously untreated.

Excluding criteria
All patients with diseases or conditions that could directly or indirectly affect the results were excluded from this study: 3. Pts previously treated with antibiotics and salicylatesin the period less than 6 months from the beginning of the study.
5. Pts with history of blood transfusions and overweight pts.
6. Pts with medications from the base line.
7. Pts with acute and chronic renal failure.
All patients voluntarily participated in this study, so the ethic criteria were fulfi lled.

Laboratory assessment
For clinical assessment of the basic disease the following laboratory variables were necessary to be taken into account: Complete Blood Count (CBC), differential blood count, reactants of the acute phase, ACPA antibodies, C-Reactive Protein (CRP), Rheumatoid Factor (RF), Erythrocyte Sedimentation Rate (ESR), Alkaline Phosphatase (AP), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Creatine kinase (CK), Lactate Dehydrogenase (LDH), serum urea, serum creatinine. ACPA antibody was determined with semi-quantitative/ qualitative ELISA method, from manufacturer Dia-statTM (Axis-Shield Diagnostic), based upon detection of IgG antibodies in human serum/plasma directed towards synthetic cyclic citrullinated peptides that comprise modifi ed arginine residua. Calculation and interpretation of the results for the quantitative protocol is estimated from the absorbent value (optic density) from positive and negative control, for every sample. matched test for independent samples was used. P value between 0,05 and 0,1 was considered statistically signifi cant.
Data processing was made with Statistical package Statistica7.0

Results
In the group with 21 pts with SA 1 patient showed presence of ACPA antibodies, while RF was not fi nd in any patient. In the group withsacroiieitis no patient was ACPA positive, while 1 patient was RF positive (  Figure 1).
If the patients fulfi ll this clinical-diagnostic mosaic there is possibility for "overlap" syndrome i.e. transition from one into other spondyloarthropathy.
This basic concept in 1995 was accepted by the international expert group, formally for study of SA, later renamed ASAS (Assessment of SpondyloArthritis International Society) orInternational group for estimation of spondyloarthritis. It is obvious that the term spondyloarthritis prevail over the term SpA, but time will show whether this will remain so.
In the last decade the international ASAS group (Germany, There was a try to reevaluate the current qualifi cation criteria for diagnosis of SA and other SpA. A special accent was put on defi ning the infl ammatory pain in the lumbar region and its distinction from mechanical pain in the same region.

Conclusion
The fact that the prevalence of SpA is approximately 1% in common population with tendency to increase, shows the focus of interest towards this group. It hits mostly the young  Figure 1: Distribution of ACPA, RF and CRP in SI group.
Dermatological changes such as Psoriasis vulgaris; 3. Data for colitis or similar diseases (Crohn disease, Whipple disease); 4.