14 DAY TRIAL // Not smoking or quitting this vice can only help people's health and here is another reason to consider dropping the cigarette: smoking causes over one third of cases of the most severe and frequent form of rheumatoid arthritis.
Swedish researchers studied over 1,200 people with rheumatoid arthritis and 871 people matched for sex and age, without the disease.
The patients were recruited from 19 health facilities in central Sweden and the control group participants were selected randomly, from the population register.
The study participants, aged between 18 and 70, were all questioned about their smoking habits and split into three categories, depending on how much they had smoked.
Blood samples were taken from all the participants, to establish a genetic profile for susceptibility to rheumatoid arthritis and to measure the severity of their disease, according to their levels of antibodies.
The researchers concluded that smoking is an avoidable risk factor for rheumatoid arthritis, and that it accounts for more than half of cases in people who are genetically susceptible to develop the disease.
The risk of developing rheumatoid arthritis is directly proportional with the extent of cigarette smoke exposure.
The study highlighted that 61% of people suffering from the disease had its most severe form (and also the most common one), and this has been confirmed by the positive tests for anticitrullinated protein/peptide antibody (ACPA).
People who had been smoking over 20 cigarettes a day for at least 20 years – the heaviest smokers, were over 2.5 times as likely to test positive for ACPA, while the risk fell for ex-smokers, proportionally to the time they had quit smoking.
However, for the heaviest smokers the risk was still elevated, even after 20 years without cigarettes.
After all this data, the researchers figured that smoking accounted for 35% of ACPA positive cases and one in five rheumatoid arthritis cases.
Now, the risk may not be as high as for lung cancer, where smoking accounts for 90% of the cases, but it is quite close to that of coronary artery disease.
The authors mention that there are other environmental factors that can add to an increased risk of rheumatoid arthritis, like hormonal factors and air pollutants, but they highlight that their findings are enough for people who have a family history of the disease, to stop smoking.
The work is published online in the Annals of the Rheumatic Diseases.