PRTN3 and rheumatoid arthritis: The secondary analysis using the specific definition of ACPA+ showed a similar but attenuated association between asthma and pre-RA ACPA+ RA (unadjusted OR 2.75, 95%CI 1.11,6.85; multivariable OR 2.27, 95%CI 0.84,6.16; Additional file 1: Table S1).