Smoking can have harmful effects on your skin and joints, increasing the risk and severity of the scaling skin disease psoriasis, and the arthritis that often accompanies it – psoriatic arthritis (PsA). Several studies have found an association between smoking and psoriatic arthritis, but further research is needed to gain a better understanding of cause and effect.
In a 2014 study published in Annals of the Rheumatic Diseases, researchers in Denmark investigated the smoking-psoriatic arthritis connection in 1,388 psoriatic arthritis patients from a nationwide registry. They found that compared with non-smoking psoriatic arthritis patients, smoking PsA patients had worse self-reported disease. Smokers also had shorter treatment adherence (meaning they didn’t follow their prescribed treatment plan for as long) and a poorer response to treatment.
Other studies have shown more negative effects of smoking on psoriatic arthritis. A Swedish study examining the effects of smoking habits in 1,185 people with psoriatic arthritis, for example, found that both current and past smokers reported worse pain and fatigue and more painful regions than those who had never smoked. The study, published in 2015 in Clinical Rheumatology, also found that smokers reported worse health overall; however, the authors note that impaired health status could also be an effect of other smoking-related problems, like lung function.
A British study investigating predictors of poor physical function in people with established PsA found that smoking, older age at diagnosis and delayed diagnosis all had a similar negative effect on patients’ long-term physical function. The study of 267 patients who had had psoriatic arthritis for 10 years or longer was published in Annals of the Rheumatic Diseases in 2012.
A 2011 study published by U.S. researchers in Annals of the Rheumatic Diseases showed that smoking not only was associated with severe psoriatic arthritis and worse outcomes, but that it may play a role in the disease’s development as well.
Harvard researchers evaluated the association between smoking and the incidence of psoriatic arthritis among 94, 874 participants in large study of female health professionals who completed health-related questionnaires every two years for 14 years. The researchers identified 157 women who developed psoriatic arthritis during the time they were in the study. The risk was greater for those who currently or previously smoked. In fact, those who were smokers at the start of the study were three times as likely to develop psoriatic arthritis as those who never smoked. For past smokers the picture was a little better – but not much. They had a 50 percent greater risk compared to those who had never smoked. The greatest risk of developing PsA was among those who smoked the most, the researchers found.
None of the studies explain how smoking increases the risk or severity of disease, nor do they predict if or how much quitting smoking might help existing disease. The lower rate of psoriatic arthritis in past than current smokers in the Harvard study, however, suggests that kicking the habit might reduce your risk of developing psoriatic arthritis in the first place.
Regardless, researchers say giving up cigarettes is worthwhile because of the many health benefits it offers. Improvements in psoriasis and psoriatic arthritis may well be among them.