Table 2

Incidence of RA in relation to RF findings in original blood samples from 1974–1987

Increased RF isotypes in original blood samplesDevelopment of RA during the study period
NumberFollow up period
(mean)
Annual incidence (%)
One RF isotype (n=64)2 (3.1%)2-150 15.60.20
Two or three RF istotypes (n=56)5 (8.9%) 17.70.50
Total (n=120)7 (5.8%)16.50.35
  • 2-150 One of these two patients had both IgM and IgA RF raised in his 1996 sample. Four of these patients had combined increase of IgM and IgA RF.