Multiplehttp://msj.sagepub.com/ Sclerosis Journal
Risk factors for multiple sclerosis, neuromyelitis optica and transverse myelitis KC Simon, H Schmidt, S Loud and A Ascherio Mult Scler published online 10 October 2014 DOI: 10.1177/1352458514551780 The online version of this article can be found at: http://msj.sagepub.com/content/early/2014/09/26/1352458514551780
Published by: http://www.sagepublications.com
On behalf of: European Committee for Treatment and Research in Multiple Sclerosis
Americas Committee for Treatment and Research in Multiple Sclerosis
Pan-Asian Committee for Treatment and Research in Multiple Sclerosis
Latin American Committee on Treatment and Research of Multiple Sclerosis
Additional services and information for Multiple Sclerosis Journal can be found at: Email Alerts: http://msj.sagepub.com/cgi/alerts Subscriptions: http://msj.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
>> OnlineFirst Version of Record - Oct 10, 2014 What is This?
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551780
research-article2014
MSJ0010.1177/1352458514551780Multiple Sclerosis JournalKC Simon, H Schmidt
MULTIPLE SCLEROSIS MSJ JOURNAL
Research Paper
Risk factors for multiple sclerosis, neuromyelitis optica and transverse myelitis
Multiple Sclerosis Journal 1–7 DOI: 10.1177/ 1352458514551780 © The Author(s), 2014. Reprints and permissions: http://www.sagepub.co.uk/ journalsPermissions.nav
KC Simon, H Schmidt, S Loud and A Ascherio
Abstract Background: Little is known about risk factors for neuromyelitis optica (NMO) or transverse myelitis (TM). Objective: The objective of this paper is to evaluate whether established multiple sclerosis (MS) risk factors, including smoking history, a history of infectious mononucleosis (IM), anti-EBNA1 Ab titers and HLA-DR15 are associated with NMO or TM. Methods: We conducted a case-control study among participants in the Accelerated Cure Project for Multiple Sclerosis (ACP) Repository, which includes patients with MS, NMO and TM. Controls include related and unrelated individuals without evidence of demyelinating disease. Analyses included 1237 cases of MS, 98 cases of NMO, 133 cases of TM and 488 healthy controls. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess the association between smoking, HLA-DR15, antiEBNA1 Ab titers and a history of IM adjusting for gender, study site and ethnicity. Results: Overall, the association between smoking, IM, HLA-DR15 and anti-EBNA1 Ab titers and odds of MS were as expected and no significant interactions were observed. However, there was little evidence of association between these MS risk factors and odds of NMO or TM. Conclusions: Established MS risk factors do not appear to be associated with susceptibility to TM or NMO and, among MS patients, these risk factors appear to act independently.
Keywords: Multiple sclerosis, transverse myelitis, neuromyelitis optica, case control studies, risk factors in epidemiology, all demyelinating disease (CNS), Epstein-Barr virus Date received: 16 May 2014; revised: 11 August 2014; accepted: 12 August 2014
Introduction There are several nongenetic factors consistently associated with increased susceptibility to multiple sclerosis (MS), including vitamin D insufficiency, a history of infectious mononucleosis (IM), a history of smoking and high antibody titers against Epstein-Barr nuclear antigen (anti-EBNA).1,2 Several genetic factors have also been implicated, most notably HLADRB1*1501 and other major histocompatibility complex (MHC) alleles,3 with more modest contributions from several other loci.4 Additionally, women appear to be approximately two to three times more likely to develop MS than men.5 We examined the distribution of these risk factors among MS, transverse myelitis (TM) and neuromyelitis optica (NMO)
patients and healthy control individuals recruited as part of the ongoing Accelerated Cure Project (ACP) Repository study. This study includes a large number of MS patients (>1200 at the time of our analysis) and patients with other demyelinating diseases, with detailed personal history information obtained via structured interview as well as repeated collection of biospecimens for biomarker analysis. In particular, we sought to investigate potential interactions between established MS risk factors in relation to MS susceptibility as well as to characterize the association between established MS risk factors and susceptibility to NMO or TM, two conditions for which epidemiologic data are limited to studies of incidence or prevalence, or, for TM, antecedent infections.6,7
Correspondence to: Alberto Ascherio Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA. [email protected] KC Simon Department of Nutrition, Harvard School of Public Health, USA/Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, USA H Schmidt S Loud Accelerated Cure Project, USA A Ascherio Department of Nutrition, Harvard School of Public Health, USA/Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, USA/Department of Epidemiology, Harvard School of Public Health, USA
http://msj.sagepub.com 1
Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
Multiple Sclerosis Journal Materials and methods Study population This study includes participants in the ACP Repository. Full details of the study and all relevant documentation can be found at www.acceleratedcure.org. Enrollment in the study began in May 2006 and participants have been recruited at 10 MS specialty clinic sites. Patients are identified from the patient base or recruited from the surrounding communities at each collection site and, if interested, are screened against the exclusion/inclusion criteria. Inclusion criteria include 1) at least one demyelinating event characteristic of MS, optic neuritis (ON), NMO, TM or acute disseminated encephalomyelitis (ADEM) (demyelinating event is defined as a symptom or constellation of symptoms referable to a disruption of the central nervous system (CNS) white matter or myelin within gray matter. Characteristic syndromes include hemibody sensory or motor symptoms, mono-sensory symptoms, monoparesis, brainstem syndrome or cerebellar syndrome, lasting at least 24 hours and not acute in onset). The diagnostic criteria for each condition were consistent with the current in-use standard at the time of enrollment. All NMO and NMO spectrum disorder cases met criteria described by Wingerchuk et al.8 or were antibody positive in the setting of a clinical event consistent with NMO (i.e. TM or ON). 2) At least 18 years old and able to give informed consent or less than 18 years old with parental permission and ability to give assent and 3) individuals > 18 years willing and able to provide up to 110 ml blood via venipuncture or less than 18 years willing and able to give 50 ml. Case exclusion criteria include 1) individuals with clinical or radiological evidence of stroke, meningitis, neoplastic, peripheral nervous system or primary muscle disease, or other well-characterized and defined diseases of the nervous system excepting those under study (see inclusion criteria 1), 2) individuals with a history of blood-borne pathogens, 3) individuals with a history of allogeneic bone marrow transplant and 4) individuals < 37 pounds. Controls, unrelated and related, are referred by the cases. Controls include related and unrelated individuals who have not experienced any CNS demyelinating events characteristic of MS, TM, ADEM, NMO or ON and have not been diagnosed with any demyelinating disease. Inclusion criteria 2) and 3) and all exclusion criteria for cases apply for controls. At the time of our receipt of samples (October 2010), we had demographic data on a study that included 2038 participants (including 1237 MS, 488 controls, 100 NMO (of whom were 61 with documented immunoglobulin G (IgG) positivity), 134 TM, 10 ON, 22 ADEM, and 47 clinically isolated syndrome (CIS)). We restricted our
analysis to participants for whom we received serum samples and reported symptom onset after 8 years of age (i.e. youngest reported first symptoms at age 9) resulting in 1190 MS, 97 NMO, 124 TM and 454 healthy controls (394 of whom were related to the cases) for analysis. Deviations from this total are noted in Table 1. We additionally had serum samples from 43 patients diagnosed with a CIS, though DNA was not available for them, and they were not included in the main analyses. This study was approved by necessary institutional review boards. Smoking, history of IM and family history of MS Demographic, personal habits, and individual and family medical history information is collected via a case report form (CRF, available at: http://www. acceleratedcure.org/impact/repository/documents) administered by the study staff. This includes detailed information on smoking history and IM, family history of MS, race and age. For cases, IM and smoking history were assessed before the onset of symptoms. Anti-Epstein-Barr virus nuclear antigen 1 (EBNA1) antibody (Ab) titers Each ACP Repository participant provided blood samples for use in research. Serum was processed into aliquots at the clinical sites, stored at −70°C to −80°C at the site, and then shipped frozen to the repository’s central lab facility for storage at −80°C (SeraCare Bioservices Inc, Gaithersburg, MD). DNA was extracted from whole blood at the central lab facility. De-identified aliquots were provided for genetic and serum analysis. IgG Ab titer levels against the antiEBNA1 were measured in the laboratory of Dr Nadar Rifai at the Children’s Hospital Boston using a commercially available enzyme-linked immunosorbent assay (ELISA) that was modified for quantitative analysis relative to known standards. The validity of this method was assessed by comparing MS case and control samples previously measured using immunofluorescence with this ELISA method. In analyses, standardized anti-EBNA1 titers predicted similar odd ratios (ORs) of MS and had high correlations (0.85) supporting the validity of this developed assay in measuring titers. The interassay coefficient of variation (CV) was 3.5 and intra-assay CV was 5.8. Although anti-EBNA1 titers were measured in serum samples collected after the diagnosis of MS, unlike our previous studies that relied on prospectively collected samples,9–11 we have previously found that anti-EBNA1 titers remain stable after MS diagnosis,9 and therefore titers measured after the diagnosis are a reasonable proxy for titers before MS onset.
2 http://msj.sagepub.com
Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
KC Simon, H Schmidt et al. Table 1. Descriptive characteristics of MS, NMO and TM patients and healthy controls selected into the ACP study. Multiple sclerosis
Neuromyelitis optica
Transverse myelitis
Controls
n = 1190
n = 97
n = 124
n = 454
Average age at interview (SD) Female Ethnicity Hispanic/Latino Not Hispanic/Latino Race American Indian/Alaskan native Middle Eastern South Asian Other Asian Black/African American Native Hawaiian or other Pacific Islander White History of infectious mononucleosis (IM) Yesa Average age at mono (SD) Average age at diagnosis (range) Average age at first symptom – years (range) Average disease duration-years (SD) Ever smoker (%) HLA-DR15 positive n (%)b EBV negative n (%) Mean anti-EBNA1 IgG Ab titer
46 (11) 928 (78%)
46 (13) 80 (82%)
49 (13) 83 (67%)
39 (3%) 1125 (97%)
7 (8%) 85 (92%)
0 124 (100%)
4 (
Risk factors for multiple sclerosis, neuromyelitis optica and transverse myelitis KC Simon, H Schmidt, S Loud and A Ascherio Mult Scler published online 10 October 2014 DOI: 10.1177/1352458514551780 The online version of this article can be found at: http://msj.sagepub.com/content/early/2014/09/26/1352458514551780
Published by: http://www.sagepublications.com
On behalf of: European Committee for Treatment and Research in Multiple Sclerosis
Americas Committee for Treatment and Research in Multiple Sclerosis
Pan-Asian Committee for Treatment and Research in Multiple Sclerosis
Latin American Committee on Treatment and Research of Multiple Sclerosis
Additional services and information for Multiple Sclerosis Journal can be found at: Email Alerts: http://msj.sagepub.com/cgi/alerts Subscriptions: http://msj.sagepub.com/subscriptions Reprints: http://www.sagepub.com/journalsReprints.nav Permissions: http://www.sagepub.com/journalsPermissions.nav Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
>> OnlineFirst Version of Record - Oct 10, 2014 What is This?
Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
551780
research-article2014
MSJ0010.1177/1352458514551780Multiple Sclerosis JournalKC Simon, H Schmidt
MULTIPLE SCLEROSIS MSJ JOURNAL
Research Paper
Risk factors for multiple sclerosis, neuromyelitis optica and transverse myelitis
Multiple Sclerosis Journal 1–7 DOI: 10.1177/ 1352458514551780 © The Author(s), 2014. Reprints and permissions: http://www.sagepub.co.uk/ journalsPermissions.nav
KC Simon, H Schmidt, S Loud and A Ascherio
Abstract Background: Little is known about risk factors for neuromyelitis optica (NMO) or transverse myelitis (TM). Objective: The objective of this paper is to evaluate whether established multiple sclerosis (MS) risk factors, including smoking history, a history of infectious mononucleosis (IM), anti-EBNA1 Ab titers and HLA-DR15 are associated with NMO or TM. Methods: We conducted a case-control study among participants in the Accelerated Cure Project for Multiple Sclerosis (ACP) Repository, which includes patients with MS, NMO and TM. Controls include related and unrelated individuals without evidence of demyelinating disease. Analyses included 1237 cases of MS, 98 cases of NMO, 133 cases of TM and 488 healthy controls. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess the association between smoking, HLA-DR15, antiEBNA1 Ab titers and a history of IM adjusting for gender, study site and ethnicity. Results: Overall, the association between smoking, IM, HLA-DR15 and anti-EBNA1 Ab titers and odds of MS were as expected and no significant interactions were observed. However, there was little evidence of association between these MS risk factors and odds of NMO or TM. Conclusions: Established MS risk factors do not appear to be associated with susceptibility to TM or NMO and, among MS patients, these risk factors appear to act independently.
Keywords: Multiple sclerosis, transverse myelitis, neuromyelitis optica, case control studies, risk factors in epidemiology, all demyelinating disease (CNS), Epstein-Barr virus Date received: 16 May 2014; revised: 11 August 2014; accepted: 12 August 2014
Introduction There are several nongenetic factors consistently associated with increased susceptibility to multiple sclerosis (MS), including vitamin D insufficiency, a history of infectious mononucleosis (IM), a history of smoking and high antibody titers against Epstein-Barr nuclear antigen (anti-EBNA).1,2 Several genetic factors have also been implicated, most notably HLADRB1*1501 and other major histocompatibility complex (MHC) alleles,3 with more modest contributions from several other loci.4 Additionally, women appear to be approximately two to three times more likely to develop MS than men.5 We examined the distribution of these risk factors among MS, transverse myelitis (TM) and neuromyelitis optica (NMO)
patients and healthy control individuals recruited as part of the ongoing Accelerated Cure Project (ACP) Repository study. This study includes a large number of MS patients (>1200 at the time of our analysis) and patients with other demyelinating diseases, with detailed personal history information obtained via structured interview as well as repeated collection of biospecimens for biomarker analysis. In particular, we sought to investigate potential interactions between established MS risk factors in relation to MS susceptibility as well as to characterize the association between established MS risk factors and susceptibility to NMO or TM, two conditions for which epidemiologic data are limited to studies of incidence or prevalence, or, for TM, antecedent infections.6,7
Correspondence to: Alberto Ascherio Department of Nutrition, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115, USA. [email protected] KC Simon Department of Nutrition, Harvard School of Public Health, USA/Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, USA H Schmidt S Loud Accelerated Cure Project, USA A Ascherio Department of Nutrition, Harvard School of Public Health, USA/Channing Laboratory, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, USA/Department of Epidemiology, Harvard School of Public Health, USA
http://msj.sagepub.com 1
Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
Multiple Sclerosis Journal Materials and methods Study population This study includes participants in the ACP Repository. Full details of the study and all relevant documentation can be found at www.acceleratedcure.org. Enrollment in the study began in May 2006 and participants have been recruited at 10 MS specialty clinic sites. Patients are identified from the patient base or recruited from the surrounding communities at each collection site and, if interested, are screened against the exclusion/inclusion criteria. Inclusion criteria include 1) at least one demyelinating event characteristic of MS, optic neuritis (ON), NMO, TM or acute disseminated encephalomyelitis (ADEM) (demyelinating event is defined as a symptom or constellation of symptoms referable to a disruption of the central nervous system (CNS) white matter or myelin within gray matter. Characteristic syndromes include hemibody sensory or motor symptoms, mono-sensory symptoms, monoparesis, brainstem syndrome or cerebellar syndrome, lasting at least 24 hours and not acute in onset). The diagnostic criteria for each condition were consistent with the current in-use standard at the time of enrollment. All NMO and NMO spectrum disorder cases met criteria described by Wingerchuk et al.8 or were antibody positive in the setting of a clinical event consistent with NMO (i.e. TM or ON). 2) At least 18 years old and able to give informed consent or less than 18 years old with parental permission and ability to give assent and 3) individuals > 18 years willing and able to provide up to 110 ml blood via venipuncture or less than 18 years willing and able to give 50 ml. Case exclusion criteria include 1) individuals with clinical or radiological evidence of stroke, meningitis, neoplastic, peripheral nervous system or primary muscle disease, or other well-characterized and defined diseases of the nervous system excepting those under study (see inclusion criteria 1), 2) individuals with a history of blood-borne pathogens, 3) individuals with a history of allogeneic bone marrow transplant and 4) individuals < 37 pounds. Controls, unrelated and related, are referred by the cases. Controls include related and unrelated individuals who have not experienced any CNS demyelinating events characteristic of MS, TM, ADEM, NMO or ON and have not been diagnosed with any demyelinating disease. Inclusion criteria 2) and 3) and all exclusion criteria for cases apply for controls. At the time of our receipt of samples (October 2010), we had demographic data on a study that included 2038 participants (including 1237 MS, 488 controls, 100 NMO (of whom were 61 with documented immunoglobulin G (IgG) positivity), 134 TM, 10 ON, 22 ADEM, and 47 clinically isolated syndrome (CIS)). We restricted our
analysis to participants for whom we received serum samples and reported symptom onset after 8 years of age (i.e. youngest reported first symptoms at age 9) resulting in 1190 MS, 97 NMO, 124 TM and 454 healthy controls (394 of whom were related to the cases) for analysis. Deviations from this total are noted in Table 1. We additionally had serum samples from 43 patients diagnosed with a CIS, though DNA was not available for them, and they were not included in the main analyses. This study was approved by necessary institutional review boards. Smoking, history of IM and family history of MS Demographic, personal habits, and individual and family medical history information is collected via a case report form (CRF, available at: http://www. acceleratedcure.org/impact/repository/documents) administered by the study staff. This includes detailed information on smoking history and IM, family history of MS, race and age. For cases, IM and smoking history were assessed before the onset of symptoms. Anti-Epstein-Barr virus nuclear antigen 1 (EBNA1) antibody (Ab) titers Each ACP Repository participant provided blood samples for use in research. Serum was processed into aliquots at the clinical sites, stored at −70°C to −80°C at the site, and then shipped frozen to the repository’s central lab facility for storage at −80°C (SeraCare Bioservices Inc, Gaithersburg, MD). DNA was extracted from whole blood at the central lab facility. De-identified aliquots were provided for genetic and serum analysis. IgG Ab titer levels against the antiEBNA1 were measured in the laboratory of Dr Nadar Rifai at the Children’s Hospital Boston using a commercially available enzyme-linked immunosorbent assay (ELISA) that was modified for quantitative analysis relative to known standards. The validity of this method was assessed by comparing MS case and control samples previously measured using immunofluorescence with this ELISA method. In analyses, standardized anti-EBNA1 titers predicted similar odd ratios (ORs) of MS and had high correlations (0.85) supporting the validity of this developed assay in measuring titers. The interassay coefficient of variation (CV) was 3.5 and intra-assay CV was 5.8. Although anti-EBNA1 titers were measured in serum samples collected after the diagnosis of MS, unlike our previous studies that relied on prospectively collected samples,9–11 we have previously found that anti-EBNA1 titers remain stable after MS diagnosis,9 and therefore titers measured after the diagnosis are a reasonable proxy for titers before MS onset.
2 http://msj.sagepub.com
Downloaded from msj.sagepub.com at University of North Carolina at Chapel Hill on November 1, 2014
KC Simon, H Schmidt et al. Table 1. Descriptive characteristics of MS, NMO and TM patients and healthy controls selected into the ACP study. Multiple sclerosis
Neuromyelitis optica
Transverse myelitis
Controls
n = 1190
n = 97
n = 124
n = 454
Average age at interview (SD) Female Ethnicity Hispanic/Latino Not Hispanic/Latino Race American Indian/Alaskan native Middle Eastern South Asian Other Asian Black/African American Native Hawaiian or other Pacific Islander White History of infectious mononucleosis (IM) Yesa Average age at mono (SD) Average age at diagnosis (range) Average age at first symptom – years (range) Average disease duration-years (SD) Ever smoker (%) HLA-DR15 positive n (%)b EBV negative n (%) Mean anti-EBNA1 IgG Ab titer
46 (11) 928 (78%)
46 (13) 80 (82%)
49 (13) 83 (67%)
39 (3%) 1125 (97%)
7 (8%) 85 (92%)
0 124 (100%)
4 (
