Does smoking impact seropositivity levels in patients with rheumatoid arthritis?

This study assessed the link between smoking and seropositivity levels of specific autoantibodies in patients with rheumatoid arthritis (RA). The authors concluded that patients with RA who were current smokers had significantly higher seropositivity levels than those that never smoked.

Smoking is an environmental risk factor that is implicated in many inflammatory diseases, such as RA.

A strong link exists between smoking and RA in patients who are seropositive for the autoantibodies rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA). Autoantibodies are harmful since they inappropriately target and harm tissues like joints and destroy them. Genetic factors are believed to also have a role in the activity of these autoantibodies.

Although a link between smoking and seropositivity has been previously reported, whether smoking also affects the levels of seropositivity in patients with RA is still unknown.

The study involved 3439 patients with RA from 17 countries. Group 1 included 705 patients who were either current smokers or quitters for less than 3 years. Group 2 included 2734 patients who were never smokers or were quitters for over 3 years. Seropositivity status was determined as high positive, low positive, or negative.

Significantly more patients in group 1 (62.7%) were highly positive for RF and/or ACPA compared to group 2 (56.9%). Patients in group 1 were 27% more likely to be highly positive for RF and/or ACPA compared to those in group 2. Significantly more patients in group 2 (24.4%) were low-positive for these autoantibodies compared to group 1 (19.7%).

456 patients were current smokers, 2191 patients had never smoked. Significantly more current smokers were highly seropositive (62.7%) compared to those that never smoked (56.4%). Current smokers were 30% more likely to have high seropositivity levels compared to never smokers.

The study showed that patients with RA who currently smoked had high seropositivity levels for RF and ACPA compared to those that never smoked.

The study had grouped the autoantibodies so interpretation was not done separately at the RF and ACPA levels. Also, there was no data on other RA parameters such as disease activity or joint damage. Further studies are needed.