Background The association between cigarette smoking and the risk of developing systemic lupus erythematosus (SLE) remains a matter of debate. The aim of this study is testing the hypothesis that there is a larger proportion of smokers among SLE patients at symptom debut compared to controls.

Methods Two hundred and fifty five SLE patients fulfilling the ACR classification criteria responded to a questionnaire regarding smoking in 2010. The year of symptom development was registered. Juvenile SLE was defined as onset before 16 years of age. All men, participants below 16 years, and patients born before 1920 were excluded due to lack of proper matches in the control group. Each of the remaining 200 SLE patients had three age-matched controls. The control group consisted of 1050 females who answered a questionnaire of various health issues including smoking habits in 2012. The smoking status in the SLE patients at onset of symptoms was compared with controls. The Cochran-Mantel-Haenszel (CMH) test was used to determine the association between smoking and SLE.

Results The pooled odds ratios (OR), 95% confidence intervals for OR as well as p-values for test of the hypothesis that OR = 1 are shown in the table 1. It is found that OR >= 1 in all groups, but only statistically significant in the age group 30 – 35 and for all ages combined.

Conclusions In this study of 200 women with SLE and age-matched controls, current smoking was associated with a modestly elevated risk of SLE (OR 1.49, p<0,03). This corresponds with a previous meta study on SLE.¹ However, smoking is complex phenomenon where cultural and socioeconomic factors play a part. The relationship between cigarette smoking and SLE should be addressed in a prospective manner.

References

1. Costenbader KH, Kim DJ, Peerzada J, et al. Cigarette smoking and the risk of systemic lupus erythematosus: a metaanalysis. Arthr Rheum 2004;50:849e57.