Smoking As A Risk Factor For Rheumatoid Arthritis
Smoking also has been implicated as a possible cause of rheumatoid arthritis and become the focus of several clinical studies.
A study published in the March 2000 issue of the Journal of Rheumatology analyzes the effect of smoking on clinical, laboratory, and radiographic status in rheumatoid arthritis patients. It was the theory of the author of the study, Frederick Wolfe, M.D., that more insight could be gained if seropositive rheumatoid arthritis patients were studied separately from a group of rheumatoid arthritis patients containing both seropositive and seronegative rheumatoid arthritis patients. Seropositive and seronegative refer to the presence or absence of rheumatoid factor (RF).
Wolfe listed the objectives of his study was to:
- determine if rheumatoid factor (RF) positivity was associated with increased smoking.
- determine the quantitative effect of smoking and smoking duration on the concentration of RF in all patients and in seropositive patients separately. [liinvestigate if there is a difference in the effect of smoking in men versus women.
- confirm results of a previous study by Saag et al. which claimed that smoking was predictive of rheumatoid nodules, radiographic erosions, and radiographic severity.
- analyze the effect of smoking on disease activity measures (sedimentation rate, joint count (the number of tender joints), Health Assessment Questionnaire disability) and disease outcome measures (pulmonary problems, Health Assessment Questionnaire disability, and Larsen radiographic abnormalities).
About The Study
Wolfe's study focused on 640 consecutive patients with rheumatoid arthritis seen at the Arthritis Center in Wichita, Kansas from July, 1991 to April, 1997. Of the 620 patients studied:
- 18 percent were current smokers
- 28 percent were past smokers.
Of those people studied, current or past smoking was more common in men than in women. About 81 percent of the patients were RF positive, and the RF was greater in men than in women.
Results revealed that among rheumatoid arthritis patients, smokers are more often RF positive than nonsmokers. Smokers were found to have higher RF values than non-smokers. After restricting the analysis to RF positive patients only, RF values were found to be significantly higher in smokers than non-smokers also.
The study results also indicated that RF values increase when correlated with duration of smoking. This was the case with either men or women, and whether the whole rheumatoid arthritis group or just the RF positive patients were considered. Also, a significant effect of smoking on radiographic progression was observed in patients with long smoking histories. Clear evidence associated smoking with erosions and nodules.
Smoking was also found to be related to pulmonary illness with a direct effect of smoking in the lungs and an indirect effect through increased RF production. No evidence was found to correlate the effect of smoking of the sedimentation rate, joint count, or Health Assessment Questionnaire scores.
From the findings in this study, it was concluded that smoking likely contributes to disease severity but not disease activity. Although the effect of smoking on rheumatoid arthritis is not completely understood, there is enough evidence which supports a correlation. Future studies will hopefully continue to define the correlation and evaluate the clinical significance of that correlation.
Sources: The Effect Of Smoking On Clinical, Laboratory, and Radiographic Status in Rheumatoid Arthritis, Frederick Wolfe, M.D., The Journal Of Rheumatology, March 2000; Does Smoking Influence Disease Outcome In Patients With Rheumatoid Arthritis?, Editorial by Beverley J. Harrison, M.D. and Alan J. Silman, M.D., The Journal of Rheumatology, March 2000
First published: 5/01/2000