Background Difficulty in the diagnosis of early rheumatoid arthritis (ERA) in the aspect of differential diagnosis.

Objectives The diagnosis of rheumatoid arthritis (RA) is based on ACR criteria, which are clinical, radiological and immunological. During the first month after onset the diagnosis is often difficult because of a frequently ?atypical? presentation and a lack of radiological changes. Rheumatoid factor has low specify and is often negative in ERA. The other non-rheumatological disorders (viral infection, neoplastic and endocrine diseases) may also in the early stage present like RA symptoms.

The objective of this study was to revised the preliminary diagnosis of ERA in hospitalised patient.

Methods Clinical examination (including laboratory tests and X ray), immunological tests: RF, antikeratin antibodies (AKA).

Results During the last 26 month 510 RA patients (according ACR criteria) were hospitalised in Rheumatology Department. Among this group of patients 94 (18%) were admitted with the preliminary diagnosis ERA. All of this patients group fulfilled the first four clinical ACR criteria The duration of the disease was varied 3 to 9 months. All patients were carefully examined according number of painful and swollen joints, their symmetry and localisation, presence of RF, AKA antibodies and radiological erosions. In cases were RA diagnosis was doubtful other needful examination were done. The diagnosis of ERA was established in 48 (52%), but in 46 (48%) was excluded. ERA patients were predominately women, symmetrical polyarthris of the hands was present in 45 (52%). RF in 28 (58%), radiological erosions were found in 5 (10%). In group of patients with excluded ERA the following diagnosis was established: osteoarthritis 14 (31%), RA ? like (nonclassified) 13 (28%), reactive arthritis 3(7%), hepatitis viral infection 2 (4%), neo 2 (4%), Hashimoto syndrome 5 (11%), Sjogren syndrome 2 (4%), Polymialgia 2 (4%), Fibromialgia 3 (7%). AKA were present in 30 (62%) patients in group with established diagnosis of RA and RF was present in 28 (58%) patients in this group. AKA was present in 10 (21%) patients with different diagnosis and RF was observed in 8 (17%) patients in this group.

Conclusion 1) ACR criteria are insufficient in aspect of differential diagnosis of ERA and non ERA. 2) Present RF and AKA are more specific in ERA than in non ERA patients.3) The diagnosis of ERA should be established by specialists.

References

1. Hassfeld W, Steiner G, Graninger W, Witzmann G, Schweitzer H, Smolen JS. Autoantibody to the nuclear antigen RA 33: a marker for early RA. Br J Rheumatol. 1993;32:199–203

2. Paimela L, Gripenberg M, Kuski P, Leirisalo ? Repo M. Antikeratin antibodies: diagnostic and progostic markers for early rheumatoid arthritis. Ann Rheum Dis. 1992;51:743–6