BACKGROUND: Anti-citrullinated peptides antibodies (ACPA) are specific for 
rheumatoid arthritis and have been implicated in disease pathogenesis. ACPA 
examination is a new component of ACR/EULAR 2010 classification criteria for 
rheumatoid arthritis. ACPA positivity predicts a more erosive disease course 
with severe joint damage and extra-articular manifestations.
OBJECTIVES: To evaluate the benefits of ACPA examination in patients with early 
undifferentiated arthritis and patients with rheumatoid arthritis.
METHODS: We examined patients with arthritis and tested them for ACPA 
positivity. In every individual patient we evaluated if ACPA examination was 
necessary to establish the diagnosis of rheumatoid arthritis, or to change 
treatment, or if the diagnosis could have been established without ACPA 
examination (ACR/EULAR 2010 classification criteria was met without ACPA 
scoring).
RESULTS AND CONCLUSIONS: The study was placed in Slovak Republic. We examined 
833 patients with arthritis. There were 43 patients, or 62% of a subgroup of 69 
who were ACPA positive whose ACPA examination was not needed-ACR/EULAR criteria 
was met without ACPA scoring. This number represents 5.1% of the total number 
examined. There were 15 patients, or 22% of the subgroup and 1.8% of the total 
whose diagnosis was revised to rheumatoid arthritis due to ACPA 
positivity-ACR/EULAR criteria were met solely with ACPA scoring. There were 11 
patients (16% and 1.3%) whose medication was changed due to ACPA positivity. 
ACPA examination is useful in 3.1% of all examined patients. When we correlate 
data on ACPA positive patients, 38% of the patients profit from ACPA 
examinations. Considering the relatively low price of ACPA testing, this 
examination should not be excluded.