Rheumatoid Arthritis: Smoking Exacerbates Disease Activity

Pam Harrison

March 04, 2014

WHISTLER, CANADA — Smoking appears to exacerbate disease activity in patients with rheumatoid arthritis (RA) regardless of background therapy, registry evidence suggests.

Binu Jacob, PhD, from the Toronto Hospital Research Institute, Ontario, Canada, and colleagues found that disease activity, as reflected by swollen and tender joint counts along with patient-reported measures of disease activity, were significantly higher in current smokers than in never smokers, even after adjusting for age, sex, and rheumatoid factor.

In contrast, the baseline treatment regimen was not affected by smoking status.

"Smoking is a well established risk factor for developing RA, but not many studies have shown an effect of smoking on disease activity," Dr. Jacob said. "And while we don't know for sure what effect smoking is having on the disease, I think it may be interfering with the effect of treatment."

The study was presented here during the 69th Annual Meeting of the Canadian Rheumatology Association.

Ontario Initiative

The investigators analyzed data on 2090 patients with RA enrolled in Ontario Best Practices Research Initiative (OBRI). The OBRI is a clinical registry of patients with RA followed-up in routine care.

Patients were divided into 3 groups: never smokers, past smokers, and current smokers. Baseline demographics, treatment regimens, and disease activity indices were then compared across the 3 groups.

In the overall cohort, 16.4% of patients were identified as current smokers, another 38.9% were past smokers, and 44.7% were never smokers.

Several different physician- and patient-based disease activity scores were all significantly higher for smokers compared with never smokers. Disease activity scores in past smokers mirrored those of the never smokers.

However, there were no significant differences in the Disease Activity Score in 28 Joints among the 3 groups.

Table. Measures of Disease Activity: Physician- and Patient-Based

Measure Never Smokers Current Smokers P Values
Tender joints 6.3 7.6 <0.001
Swollen joints 6.4 7.1 <0.001
Clinical Disease Activity Index 21.6 24.3 0.0014
Simple Disease Activity Index 23.3 26.2 0.0165
Rheumatoid Arthritis Disease Activity Index 3.7 4.5 <0.001

In terms of demographic differences between the groups, the researchers found that significantly more never smokers were women, had postsecondary education, and were married than current smokers.

In contrast, current smokers were significantly more likely to list English as their first language, drink alcohol, and test positive for rheumatoid factor than never smokers.

"The implications of these findings are really for patients themselves," Dr. Jacob told Medscape Medical News. "If patients realize that smoking is making their disease activity worse, they may think, if I quit smoking, I could feel better. Even if physicians make most of the treatment decisions, patients need to know that by changing their lifestyle, they may improve their disease as well."

Dr. Jacob has disclosed no relevant financial relationships.

69th Annual Meeting of the Canadian Rheumatology Association: Abstract 145. Presented February 28, 2014.

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