Eva R Petersen1, Annette B Oturai2, Nils Koch-Henriksen2, Melinda Magyari2, Per S Sørensen2, Finn Sellebjerg2, Helle B Søndergaard2. 1. From the Danish Multiple Sclerosis Center (E.R.P., A.B.O., M.M., P.S.S., F.S., H.B.S.), Department of Neurology, and Danish Multiple Sclerosis Treatment Register (N.K.-H., M.M.), Rigshospitalet, University of Copenhagen; and Department of Clinical Epidemiology (N.K.-H), Clinical Institute, University of Aarhus, Denmark. Evarosapetersen@gmail.com. 2. From the Danish Multiple Sclerosis Center (E.R.P., A.B.O., M.M., P.S.S., F.S., H.B.S.), Department of Neurology, and Danish Multiple Sclerosis Treatment Register (N.K.-H., M.M.), Rigshospitalet, University of Copenhagen; and Department of Clinical Epidemiology (N.K.-H), Clinical Institute, University of Aarhus, Denmark.
Abstract
OBJECTIVE: To investigate whether smoking in patients with relapsing-remitting multiple sclerosis (RRMS) treated with interferon beta (IFN-β) is associated with the relapse rate and whether there is an interaction between smoking and human leukocyte antigen (HLA)-DRB1*15:01, HLA-A*02:01, and the N-acetyltransferase-1 (NAT1) variant rs7388368A. METHODS: DNA from 834 IFN-β-treated patients with RRMS from the Danish Multiple Sclerosis Biobank was extracted for genotyping. Information about relapses from 2 years before the start of treatment to either the end of treatment or the last follow-up visit was obtained from the Danish Multiple Sclerosis Treatment Register. Smoking information came from a comprehensive questionnaire. RESULTS: We found that the relapse rate in patients with RRMS during IFN-β treatment was higher in smokers compared to nonsmokers, with an incidence rate ratio (IRR) of 1.20 (95% confidence interval [CI] 1.021-1.416, p = 0.027) and with an IRR increase of 27% per pack of cigarettes per day (IRR 1.27, 95% CI 1.056-1.537, p = 0.012). We found no association or interaction with HLA and the NAT1 variant. CONCLUSION: In this observational cohort study, we found that smoking is associated with increased relapse activity in patients with RRMS treated with IFN-β, but we found no association or interaction with HLA or the NAT1 variant.
OBJECTIVE: To investigate whether smoking in patients with relapsing-remitting multiple sclerosis (RRMS) treated with interferon beta (IFN-β) is associated with the relapse rate and whether there is an interaction between smoking and humanleukocyte antigen (HLA)-DRB1*15:01, HLA-A*02:01, and the N-acetyltransferase-1 (NAT1) variant rs7388368A. METHODS: DNA from 834 IFN-β-treated patients with RRMS from the Danish Multiple Sclerosis Biobank was extracted for genotyping. Information about relapses from 2 years before the start of treatment to either the end of treatment or the last follow-up visit was obtained from the Danish Multiple Sclerosis Treatment Register. Smoking information came from a comprehensive questionnaire. RESULTS: We found that the relapse rate in patients with RRMS during IFN-β treatment was higher in smokers compared to nonsmokers, with an incidence rate ratio (IRR) of 1.20 (95% confidence interval [CI] 1.021-1.416, p = 0.027) and with an IRR increase of 27% per pack of cigarettes per day (IRR 1.27, 95% CI 1.056-1.537, p = 0.012). We found no association or interaction with HLA and the NAT1 variant. CONCLUSION: In this observational cohort study, we found that smoking is associated with increased relapse activity in patients with RRMS treated with IFN-β, but we found no association or interaction with HLA or the NAT1 variant.
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