A history of smoking raises the risk of psoriasis in the general population, according to meta-analysis findings. However, the research also shows that, among people with psoriasis, ever-smoking may be associated with a lower risk of psoriatic arthritis (PsA).
“The latter may be also due to the collider effect,” the researchers wrote. “Whether smoking cessation neutralizes the risk of developing psoriasis requires a well-defined smoking data collection for the past history, and this is currently unavailable in the literature.”
Through their systematic literature review, the researchers identified studies published from January 1980 to July 2019 with clear information on participants’ cigarette smoking. In all, 16 studies on psoriasis, 3 studies on PsA involving the general population, and 4 studies on PsA involving patients with psoriasis met inclusion criteria for the meta-analysis.
The prevalence of ever-smoking was increased among individuals with psoriasis compared with the general population, the researchers found. The study identified an odds ratio (OR) of 1.84 (95% confidence interval (CI): 1.4, 2.3).
“For PsA, the prevalence of ever smoking was reduced in psoriasis patients (OR: 0.70; 95% CI: 0.60, 0.81), but not changed compared with the general population (OR: 1.10; 95% CI: 0.92, 1.32),” the researchers wrote.
Gazel U, Ayan G, Solmaz D, Akar S, Aydin SZ. The impact of smoking on prevalence of psoriasis and psoriatic arthritis. Rheumatology. 2020;59(10):2695-2710. doi:10.1093/rheumatology/keaa179