Background ACPA status provides important information regarding the diagnosis and prognosis of Rheumatoid Arthritis (RA). By using samples from blood bank donors that later developed RA it was shown that ACPA can already be present many years prior to the clinical onset of RA. However, little information is available on the presence of ACPA in the healthy Dutch population and the actual predictive power of ACPA positivity towards development of RA in the future.

Objectives To determine the prevalence of ACPA in 40.227 participants from the LifeLines (LL), 3 generation, population based study (1).

Methods The LifeLines cohort consists of 167.729 persons divided over 3 generations collected cross-sectionally, in the northern provinces of The Netherlands. Participants were recruited with help of general practitioners from both rural and non-rural areas and were also recruited from different economic classes. The detection of ACPA was performed by measuring anti-CCP2 (by EliA-CCP test) on the Phadia 250 analyzer. ACPA levels ≥10 U/ml are considered positive. 40.227 LL participants were tested from March 2012 till September 2013. Also an extensive questionnaire on early symptoms of musculoskeletal disorders was sent around in 2012 and 2013. Summer 2014 we obtained detailed demographic and clinical information on the participants, including data on smoking and periodontal health. RA was defined by a combination of self-reported RA, medication (DMARD, NSAID and/or steroid) use for the indication of rheumatism and visiting a medical specialist within the last year. Mann-Whitney U and Chi-square tests, were performed to assess differences between the ACPA negative and positive LifeLines participants.

Results Of the total 40.227 individuals, 666 participants had an ACPA level ≥5 U/ml (1.7%), 401 participants had a level ≥7 U/ml (1.0%) and 306 participants had an ACPA level ≥10 U/ml (0.8%). Of the participants with an ACPA level ≥10 U/ml, 19% had RA. Furthermore these ACPA positive participants reported significantly more pack years of smoking, were more often diagnosed with diagnosed periodontitis and had more often an FDR with RA (Table 1).

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Conclusions In this large population based study, the prevalence of ACPA levels ≥10 U/ ml as estimated by the Phadia analyzer was 0.8%. Of the ACPA positive LifeLines participants, 19% were defined as having RA. Furthermore smoking, periodontitis and a FDR with RA were more frequently present in these ACPA positive LL participants.

References

1. Scholtens S, Smidt N, Swertz MA, Bakker SJ, Dotinga A, Vonk JM, van Dijk F, van Zon SK, Wijmenga C, Wolffenbuttel BH, Stolk RP. Cohort Profile: LifeLines, a three-generation cohort study and biobank. Int J Epidemiol. 2014 Dec 14. pii: dyu229. [Epub ahead of print]

Acknowledgements This study was supported by the Dutch Arthritis Association, an in kind grant of Phadia as part of the EFPIA-contribution-IMI BTCURE with a focus on citrullinated immunity in RA and by a grant of Biobanking and Biomolecular Research Infrastructure (BBMRI)-NL complementation projects.

Disclosure of Interest None declared