Patient-reported events preceding the onset of rheumatoid arthritis: possible clues to aetiology

Patients with rheumatoid arthritis (RA) often report events that they believe may have caused their disease. We attempted to characterize such causal events and the possible relationship between these and outcomes.

Between 1996 and 2004, 1,787 adult patients were included in the Better Anti-Rheumatic FarmacOTherapy (BARFOT) early RA study in Sweden. Six possible causal events at baseline were predefined. Disease Activity Score 28-joint count (DAS28) and treatment were registered at inclusion and at three, six and 12 months. The European League against Rheumatism (EULAR) response criteria were used.

A total of 1,652 patients (92%) answered the question about possible causal events. Thirty per cent (490) of the patients believed that some event in particular had caused their RA. Sixteen per cent of the patients thought that infection, 4.4% psychological trauma, 4.1% physical trauma, 2.8% surgery, 1.5% pregnancy and 1.2% vaccination had been the cause. Younger patients attributed previous infection to their RA more often than older patients. There were no differences in EULAR response up to one year between patients who reported some event or infection and patients who did not. RA thought to be caused by infection showed a seasonal trend in the month of onset. Women reported that trauma had been a cause of their RA more often than men.

Thirty per cent of the patients reported some causal event and 16% reported infection to be the cause of their RA. There were differences in gender and age in what patients reported as the cause of their RA.