Background Rheumatoid Arthritis (RA) is a chronic inflammatory disease. Many factors influence its prognosis and outcomes, including Rheumatoid Factor (RF), anti-citrullinated antibodies, co-morbidities etc. It is well known that smoking and passive smoking can cause damage to the lungs, heart and to other human body organs. Several studies have also investigated the effects of smoking in RA. However, to date, the role of passive smoking during childhood on the outcome of RA has not been studied.
Objectives In view of the recognised influence of adult smoking on the prognosis and outcome of the disease, we investigated a possible effect of passive smoking during childhood on the outcome of RA. We investigated whether there is an association between passive smoking during childhood and disease activity score (DAS 28), visual analogue score (VAS), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), erosions and nodules.
Methods Following ethical approval, we collected data from 200 patients who have been under follow up at the Rheumatology clinic at Kingston Hospital. Data were collected from the patients’ self-completed questionnaire and from their medical notes. Patients were divided in 3 subgroups according to their current smoking status: current smokers, ex-smokers and never smokers. We used 6 outcome variables: DAS 28, VAS, CRP, ESR, erosions and nodules. In univariate analysis, we used linear and logistic regression to explore the association between each outcome measure of RA and a list of potential risk factors (gender, RF, age, treatment, current smoking status, ex-smoking status, exposure to smoking during childhood). We primarily investigated the potential effect of childhood exposure on each of the RA outcomes in the whole group of patients as well as in the following subgroups: current smokers, ex-smokers, never-smokers. In exploratory analysis we summarised the characteristics of our sample : a) in the whole group of patients and b) in the subgroups defined by the smoking status.
Results We found 20% of the patients who participated in the study to be current smokers, 30% were ex-smokers and 50% were never smokers. Among the current smokers 78% were exposed to smoking during their childhood and among the ex-smokers 85% were exposed to smoking during childhood. From the never smokers only 46% were exposed. Although, no direct association was found between passive smoking during childhood and outcome of RA, results showed that exposure to smoking during childhood predicts adult smoking (p<0.05). Also we found that current smoking status influences the use of treatment in RA. Additionally, results showed that never smokers were younger compared to the groups of the current and ex-smokers, positive RF was found to be higher in the group of current smokers and female-never smokers were more than male-never smokers.
Conclusions This is the first study to examine the association of exposure to smoking during childhood with RA outcomes. No direct association was found between the two, but it was shown that exposure to smoking during childhood predicts adult smoking among RA patients and also that the current smoking status influences the use of treatment in RA. Current smokers are using biologics less. Further studies need to be carried out in other similar settings to confirm and elucidate the role of exposure to smoking during childhood on the outcome of RA.
Disclosure of Interest None Declared