Smoking is a strong risk factor for rheumatoid nodules in early rheumatoid arthritis.
OBJECTIVE
To examine whether smoking is a risk factor for rheumatoid nodules in early rheumatoid arthritis, and if so to determine the quantitative effect of smoking.


METHODS
From a cohort (n = 1589) in a structured programme for follow up of newly diagnosed cases of rheumatoid arthritis (symptoms of swollen joints < or =12 months), 112 individuals with rheumatoid nodules at inclusion were identified. Nodular patients were each compared with two age and sex matched controls without nodules from the same cohort. A detailed self administered tobacco use questionnaire was answered by 210 patients (63%).


RESULTS
Seventy patients were current smokers, 71 former smokers, and 69 had never smoked. Current smoking and former smoking were more common in patients with rheumatoid nodules compared with controls (86% v 59%) in both sexes. Positive rheumatoid factor (RF) was found more often among cases with nodules than controls (78% v 64%). Using detailed information from the questionnaires with conditional logistic regression analyses, ever having smoked was associated with an increased risk of the presence of rheumatoid nodules (odds ratio (OR) = 7.3 (95% confidence interval, 2.3 to 23.6); p = 0.001). The risk of having nodules was not obviously dose dependent when smoking duration as well as smoking amount were examined. A stratified analysis showed that only RF positive smokers had an increased risk of rheumatoid nodules. Smoking was associated with rheumatoid nodules among both men (p = 0.006) and women (p = 0.001). Tobacco use other than smoking (n = 31) was not associated with an increased risk of nodules (OR = 0.8 (0.2 to 3.4); p = 0.813).


CONCLUSIONS
There is a strong association between smoking and rheumatoid nodules in early seropositive rheumatoid arthritis.
Nyhäll-Wåhlin
B-M
BM
Department of Rheumatology, Falun Hospital, SE-791 82 Falun, Sweden. britt-marie.nyhall-wahlin@ltdalarna.se
Jacobsson
L T H
LT
Petersson
I F
IF
Turesson
C
C
D000328:Adult; D000368:Aged; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000097:blood; D012218:Rheumatoid Nodule / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D016540:Smoking Cessation; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors
D012217:Rheumatoid Factor