Table 4

Meta-analysis for disease risk in different rheumatoid arthritis (RA) subgroups divided by the presence/absence of anti-CarP and anticyclic citrullinated peptide (anti-CCP) antibodies, ever smokers compared with non-smokers

GroupCohortSmokingOR*95% CIp Value
Never N (%)Ever N (%)
CarP-FCS
CCP−/CarP-FCS− (as control group)Leiden EAC160 (52.0)148 (48.0)1.0Ref.
Swedish EIRA247 (44.5)308 (55.5)1.0Ref.
Meta-analysis1.0Ref.
CCP−/CarP-FCS+Leiden EAC31 (55.4)25 (44.6)0.870.49 to 1.550.64
Swedish EIRA24 (32.9)49 (67.1)1.670.96 to 2.890.07
Meta-analysis1.210.64 to 2.300.56
CCP+/CarP-FCS−Leiden EAC51 (51.5)48 (48.5)1.020.65 to 1.600.94
Swedish EIRA195 (35.2)359 (64.8)1.581.22 to 2.04<0.001
Meta-analysis1.320.87 to 2.020.19
CCP+/CarP-FCS+Leiden EAC119 (41.0)171 (59.0)1.551.12 to 2.150.008
Swedish EIRA141 (25.9)404 (74.1)2.271.73 to 2.97<0.001
Meta-analysis1.901.31 to 2.76<0.001
CarP-Fib
CCP−/CarP-Fib− (as control group)Leiden EAC193 (52.2)177 (47.8)1.0Ref.
Swedish EIRA235 (43.2)309 (56.8)1.0Ref.
Meta-analysis1.0Ref.
CCP−/CarP-Fib+Leiden EAC17 (50.0)17 (50.0)1.090.54 to 2.200.81
Swedish EIRA36 (42.9)48 (57.1)0.990.61 to 1.610.96
Meta-analysis1.020.69 to 1.520.92
CCP+/CarP-Fib−Leiden EAC73 (45.6)87 (54.4)1.300.90 to 1.890.17
Swedish EIRA146 (33.4)291 (66.6)1.601.21 to 2.11<0.001
Meta-analysis1.491.19 to 1.86<0.001
CCP+/CarP-Fib+Leiden EAC118 (41.0)170 (59.0)1.571.15 to 2.140.004
Swedish EIRA190 (28.7)472 (71.3)1.901.48 to 2.45<0.001
Meta-analysis1.761.45 to 2.14<0.001
  • Bold typeface indicates statistical significance.

  • *ORs in Sweden cohort adjusted for age, gender and residential areas.

  • EAC, Early Arthritis Clinic; EIRA, Epidemiological Investigation of Rheumatoid Arthritis; FCS, fetal calf serum.