A new study confirms the link between active smoking and the risk of developing rheumatoid arthritis (RA). It also suggests, for the first time, that smokers who had early life exposure to tobacco through passive smoking have a significantly increased risk for developing the disease.
RA is the most common chronic inflammatory joint disease, causing progressive joint destruction, disability and reduced life expectancy. In recent years, many potential environmental factors have been associated with an increased risk of developing RA, but so far smoking is the only one that has been extensively studied.
The findings were recently presented at the Annual European Congress of Rheumatology (EULAR) 2017 press conference.
For the study, a large population of female volunteers born between 1925 and 1950 were tracked beginning in 1990. Out of 70,598 women, a total of 1,239 patients self-reported developing RA, of which 350 cases were eligible for analysis of the link to active and passive smoking. The mean age at inclusion in the study was 49.0 years; the mean duration of follow-up was 21.2 years.
Between 1990 and 2014, 11 self-administered questionnaires were sent to the participants to collect medical, demographic, environmental and hormonal data and dietary habits. The diagnosis of RA was collected on two successive questionnaires.
Cases were considered certain if, having reported RA, they had taken an RA specific medication (methotrexate, leflunomide or a biologic) since 2004 (the period from which drug reimbursement data was available). Participants were excluded if they had an inflammatory bowel disease and/or no information on their smoking status.
Passive smoking was assessed by the following question: “When you were children, did you stay in a smoky room?” Patients were considered exposed if the answer was “yes, a few hours, or yes, several hours a day.”
The findings show that passive smoking exposure during childhood increased the association between RA risk and adult active smoking.
“Our study highlights the importance of avoiding any tobacco environment in children, especially in those with a family history of RA,” said lead author Professor Raphaèle Seror from University Hospitals of South Paris, France.
In addition, the preliminary results of a meta-analysis reveal that smoking is also related to an increased progression of structural damage to the spine in patients with ankylosing spondylitis (AS), a form of arthritis that affects the spine.
“Smoking constitutes a major risk factor not only for disease susceptibility but also disease severity in patients with AS,” said lead author Professor Servet Akar from Izmir Katip Celebi University Faculty of Medicine in Turkey.
“Rheumatologists should work hard to encourage their AS patients to quit smoking as this could have a major impact on future quality of life.”