TNF and rheumatoid arthritis: The percentage of patients with negative prevaccination serum in different treatment groups were: 1) RA on MTX, 19%; 2) RA on anti-TNF monotherapy, 16%; 3) RA on anti-TNF + MTX, 24%; 4) RA on other biologics (abatacept 1%, rituximab 4% and tocilizumab 0%); 5) SpA on anti-TNF monotherapy, 13%; 6) SpA on anti-TNF + MTX, 14%; and 7) SpA on NSAIDs/analgesics, 13%.