Table 1

Evidence for and against the possibility that cigarette smoking predisposes to rheumatoid arthritis

For Against
Three prospective cohort studies show increased risk.6-8 A retrospective case-control study showed a protective effect.12
A population based case control study shows increased risk.9 RA is more common in women than in men. Smoking is the opposite.
Monozygotic twin study shows increased risk for RA and smoking.10 Little geographical variation in RA though in the developed world smoking levels vary considerably.5 13
Smoking associates with rheumatoid factor production.5 RA may be declining,13whereas cigarette smoking is generally increasing.
Atmospheric pollution can contribute to RF positivity, and clean air legislation may have led to its decline.11 Smoking is generally more common in lower social classes, unlike RA.11
RA is a modern disease and cigarette smoking is a modern epidemic.Smoking reduces the risk of other chronic inflammatory diseases such as ulcerative colitis.14