Portal de Periódicos da CAPES

Smoking and risk of psoriasis: A nationwide cohort study

2017; Elsevier BV; Volume: 77; Issue: 3 Linguagem: Inglês

10.1016/j.jaad.2017.04.015

1097-6787

Eun Joo Lee, Kyungdo Han, Ju Hee Han, Ji Hyun Lee,

Allergic Rhinitis and Sensitization

To the Editor: Smoking is a health hazard and also a potential risk factor for psoriasis.1Naldi L. Chatenoud L. Linder D. et al.Cigarette smoking, body mass index, and stressful life events as risk factors for psoriasis: results from an Italian case-control study.J Invest Dermatol. 2005; 125: 61-67Abstract Full Text Full Text PDF PubMed Scopus (533) Google Scholar, 2Armstrong A.W. Harskamp C.T. Dhillon J.S. Armstrong E.J. Psoriasis and smoking: a systematic review and meta-analysis.Br J Dermatol. 2014; 170: 304-314Crossref PubMed Scopus (179) Google Scholar Several studies previously showed an association between smoking and the severity of psoriasis.2Armstrong A.W. Harskamp C.T. Dhillon J.S. Armstrong E.J. Psoriasis and smoking: a systematic review and meta-analysis.Br J Dermatol. 2014; 170: 304-314Crossref PubMed Scopus (179) Google Scholar, 3Richer V. Roubille C. Fleming P. et al.Psoriasis and smoking: a systematic literature review and meta-analysis with qualitative analysis of effect of smoking on psoriasis severity.J Cutan Med Surg. 2016; 20: 221-227Crossref PubMed Scopus (39) Google Scholar However, because of their small size, the results were inconclusive. We therefore examined the independent relationship between smoking status and psoriasis by performing a large-scale nationwide cohort study (institutional review board No. KC17EISE0012). We used the representative database of the Korean National Health Insurance from 2005 through 2015. A total of 17,055,608 subjects over the age of 20 years who underwent a health examination in 2005-2008 were followed for 8 years. The incidence ratio (IR) of psoriasis with a 95% confidence interval (CI) adjusted for age, sex, alcohol consumption, physical activity, body mass index, and comorbidities was estimated by Poisson regression. The hazard ratio (HR) was estimated by Cox regression analysis. The reference group comprised individuals who had never smoked (Table I). The IR (per 1000) of psoriasis was 3.71 for former smokers and 3.54 for current smokers, respectively. In multivariate analyses, compared with nonsmokers, former smokers (adjusted IR, 1.11; 95% CI, 1.10-1.12) and current smokers (adjusted IR, 1.14; 95% CI, 1.13-1.15) had a significantly higher risk for development of psoriasis. These results indicate that smoking status is an independent potential risk factor for psoriasis. In addition, the risk for psoriasis was increased with amount and duration of smoking (P for trend <.0001) (Fig 1). There was a statistically significant positive correlation between risk for psoriasis and total period of smoking (P for trend <.0001). Furthermore, the HR for psoriasis was lowest in individuals who had smoked fewer than 0.5 packs per day (HR, 1.11) and highest in individuals who smoked more than 2 packs per day (HR, 1.25).Table IAge- and multivariable-adjusted incidence rate for psoriasisSmoking statusPatients with psoriasisIncidence rate (per 1000)Age-adjusted incidence rateMultivariable-adjusted incidence rate∗Adjusted for age, sex, alcohol consumption status, exercise, body mass index, diabetes mellitus, hypertension, and dyslipidemia.Nonsmoker320,4353.161 (reference)1 (reference)Former smoker47,4773.711.20 (95% CI, 1.19-1.21)1.11 (95% CI, 1.10-1.12)Current smoker132,5663.541.23 (95% CI, 1.22-1.24)1.14 (95% CI, 1.13-1.15)P value for trend<.0001<.0001CI, Confidence interval.∗ Adjusted for age, sex, alcohol consumption status, exercise, body mass index, diabetes mellitus, hypertension, and dyslipidemia. Open table in a new tab CI, Confidence interval. Psoriasis is a chronic inflammatory disease that is mediated by Th1 and Th17 helper T cells. Smoking produces free radicals that may activate signaling pathways implicated in psoriasis, such as the mitogen-activated kinase, nuclear factor κB, and Janus kinase-STAT pathways.4Neimann A.L. Shin D.B. Wang X. Margolis D.J. Troxel A.B. Gelfand J.M. Prevalence of cardiovascular risk factors in patients with psoriasis.J Am Acad Dermatol. 2006; 55: 829-835Abstract Full Text Full Text PDF PubMed Scopus (835) Google Scholar Byproducts from smoking, such as nicotine and dioxin, activate T cells that produce interleukin 12 (IL-12), IL-17, and IL-22.5Zhu K.J. Liu Z. Liu H. et al.An association study on the CHRNA5/A3/B4 gene cluster, smoking and psoriasis vulgaris.Arch Dermatol Res. 2014; 306: 939-944Crossref PubMed Scopus (6) Google Scholar Because IL-17 is one of the major cytokines involved in the pathogenesis of psoriasis, there are mechanistic reasons to believe that smoking could contribute to development of psoriasis. In a previous meta-analysis, psoriasis was associated with smoking history, with a pooled odds ratio of 1.62 (95% CI, 1.33-1.98).2Armstrong A.W. Harskamp C.T. Dhillon J.S. Armstrong E.J. Psoriasis and smoking: a systematic review and meta-analysis.Br J Dermatol. 2014; 170: 304-314Crossref PubMed Scopus (179) Google Scholar The relationship between smoking and moderate to severe psoriasis had a pooled odds ratio of 1.72 (95% CI, 1.33-1.98).2Armstrong A.W. Harskamp C.T. Dhillon J.S. Armstrong E.J. Psoriasis and smoking: a systematic review and meta-analysis.Br J Dermatol. 2014; 170: 304-314Crossref PubMed Scopus (179) Google Scholar In the present study, former smokers and current smokers were at increased risk for the development of psoriasis and the risk was still valid after adjustment for confounding factors. Our results are consistent with those of previous studies. Meanwhile, Armstrong et al did not fully report the association between psoriasis and the amount of cigarettes smoked.2Armstrong A.W. Harskamp C.T. Dhillon J.S. Armstrong E.J. Psoriasis and smoking: a systematic review and meta-analysis.Br J Dermatol. 2014; 170: 304-314Crossref PubMed Scopus (179) Google Scholar The association between duration of smoking and psoriasis has been controversial.2Armstrong A.W. Harskamp C.T. Dhillon J.S. Armstrong E.J. Psoriasis and smoking: a systematic review and meta-analysis.Br J Dermatol. 2014; 170: 304-314Crossref PubMed Scopus (179) Google Scholar In this study, we clearly showed that there is a positive correlation between the amount and/or duration of smoking and the occurrence of psoriasis. However, our study has a limitation in that any change in smoking status after registration has not been reflected. In addition, association does not demonstrate cause and effect; therefore, further investigation is needed.