Smoking strongly associated with psoriasis, and linked to severity


A Canadian literature review has found a positive association between the prevalence of smoking and psoriasis, as well as an association between smoking and the severity of psoriasis (J Cutan Med Surg Nov. 9, 2015).

An expert opinion group of the Canadian Dermatology-Rheumatology Comorbidity Initiative conducted systematic reviews on eight comorbidities associated with rheumatoid arthritis (RA), psoriasis arthritis (PsA), and psoriasis. The group published evidencebased recommendations for the management of these comorbities in The Journal of Rheumatology (Oct. 2015; 42(10):1767–1780). Comorbidities explored included depression, obesity, cardiovascular disease, and osteoporosis.

Links observed

As part of the project, Dr. Vincent Richer, dermatologist and associate clinical professor, Centre Hospitalier de l’Université de Montréal, performed the systematic review regarding the association between smoking and psoriasis prevalence and severity.

“We observed that people with psoriasis have a higher likelihood of being a smoker,” said Dr. Richer. “Also there is some indication, though it is not as strong, that people who have higher psoriasis severity have a higher likelihood of being smokers and smoke more than people who have mild psoriasis.”

The meta-analysis of the MEDLINE, EMBASE, and Cochrane databases (1960–2012) identified a statistically significant association between smoking and psoriasis with a relative risk of 1.88 (95% CI, 1.66–2.12) for smoking in patients with psoriasis versus patients without psoriasis. Eight articles of 11 that contained data on smoking and psoriasis severity suggested that severity increases with smoking status. Dr. Richer noted that a limitation of the study is that there might be a positive publication bias.

The literature did not explore a cause and effect relationship, and consequently Dr. Richer said they cannot yet make a strong recommendation for smoking cessation to improve psoriasis.

Cause and effect relationship not determined

However, “even though the association with psoriasis is loose, I think that we can all agree that smoking cessation is good for our patients,” said Dr. Richer.

“Patients with psoriasis are at an increased risk of cardiovascular disease and so smoking cessation for that group of patients might have an even bigger benefit than in the general population.”

The expert opinion group concluded in the report that clinicians should determine the smoking status of all patients diagnosed with psoriasis (Grade of Recommendation C) and that smoking cessation should be encouraged (Grade of Recommendation D).

Smokers demonstrate lower adherence to therapy

Studies have also found, noted Dr. Richer, that smoking is linked with risk taking behaviour and possibly reduced compliance rate with prescribed therapies.

“There is some consideration that smokers might have lower adherence to their treatment,” Dr. Richer said.

“But the science is not 100 per cent clear on this yet.” Dr. Richer told THE CHRONICLE OF SKIN & ALLERGY that his patients are intrigued to hear the current evidence regarding the link between psoriasis and smoking.

“When I see my patients I discuss this association with the caveat that we do not know if stopping would improve [psoriasis].”

Dr. Richer continued, “It kind of pleases the mind that in a chronic relapsing and remitting disease that we could have some lifestyle changes that could potentially help.”

The next important question to answer, according to Dr. Richer, would be to determine if the therapeutic intervention of smoking cessation would have effects on psoriasis when controlled for other factors such as topical treatments, phototherapy, or systemic treatments. During his literature review, he found no studies specifically relating to smoking cessation and psoriasis.

With more research, “[Smoking cessation] might give [clinicians] another arrow in their quiver in this chronic disease,” added Dr. Richer.

- Previously published in The Chronicle of Skin & Allergy.


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