New research has found for the first time a link between exposure to tobacco in childhood via passive smoking and an increased risk of rheumatoid arthritis (RA) later in life.
Carried out by researchers from Izmir Katip Celebi University Faculty of Medicine and University Hospitals of South Paris, France, the study analyzed data from 70,598 female volunteers who were followed for a mean duration of 21.2 years.
The participants were asked to complete questionnaires to collect medical, demographic, environmental and hormonal data, information on dietary habits, and to assess which participants developed RA.
Questionnaires were also used to assess passive smoking, with the researchers asking participants, "When you were children, did you stay in a smoky room?" Patients were considered to be exposed to tobacco if the answer was "yes, a few hours, or yes, several hours a day."
The results showed that participants who were active smokers had an increased risk of developing RA later in life. Moreover, for the first time ever the results also showed that that this risk was even higher for those who had also been exposed to tobacco through passive smoking during childhood.
The team also found in a separate analysis that previous chronic diarrhea was associated with more than double the risk of RA, although chronic constipation or alternating between diarrhea and constipation did not have an impact.
In addition, the preliminary results of a detailed review and meta-analysis of studies also revealed that smoking is associated with increased progression of structural damage to the spine in patients with ankylosing spondylitis (AS), a painful, progressive and disabling form of arthritis caused by chronic inflammation of the joints in the spine for which smoking is already a risk factor.
"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.
"Smoking constitutes a major risk factor not only for disease susceptibility but also disease severity in patients with AS," added lead author Professor Servet Akar, "Rheumatologists should work hard to encourage their AS patients to quit smoking as this could have a major impact on future quality of life."
RA is the most common chronic inflammatory joint disease, affecting about 0.5-1% of the general population and causing progressive joint destruction, disability and reduced life expectancy.
The results were presented on Friday at the Annual European Congress of Rheumatology (EULAR) 2017 press conference.