Clinical and epidemiological profile of multiple sclerosis in a reference center in the State of Bahia, Brazil

Perfil clínico e epidemiológico da esclerose múltipla em um centro de referência do Estado da Bahia

Clinical and epidemiological profile of multiple sclerosis in a reference center in the State of Bahia, Brazil

Perfil clínico e epidemiológico da esclerose múltipla em um centro de referência do Estado da Bahia

Eduardo Cardoso^{I, II, V}; Thiago Fukuda^III; Júlio Pereira^III; Jamile Seixas^III; Rafael Miranda^III; Bernardo Rodrigues^I; Thaís Saback^III; Renata Andrade^III; Grace Cardoso^I; Rosa Martinez^IV; Juliane Avena^IV; Ailton Melo^{I, V}

^IDivisão de Neurologia e Epidemiologia, Universidade Federal da Bahia, Salvador BA, Brasil (UFBA)

^IIProfessor, Universidade Estadual de Feira de Santana BA, Brasil

^IIIEstudante de Medicina UFBA

^IVSecretaria de Saúde do Estado da Bahia

^VBrazilian Committee for Treatment and Research in Multiple Sclerosis (BCTRIMS)

ABSTRACT

Multiple sclerosis (MS) is an autoimmune, demyelinating and degenerative disease that affects the central nervous system. Its prevalence and clinical aspects vary according to the continent considered, being more frequent in Caucasians and young individuals aged 20 to 40 years. Epidemiological data from Brazil show that prevalence is variable, being more frequent in the Southern and Southeastern areas of the country, rather than in the Northern and Northeastern areas. The purpose of this paper is to describe MS clinical and epidemiological features in the State of Bahia, in the Brazilian Northeastern region. Thus, we held a cross-sectional study over the period from February to May, 2005, in the Multiple Sclerosis Patient Support Center ("Núcleo de Apoio aos Pacientes com Esclerose Múltipla") of Bahia, which included all patients with a diagnosis of MS seen over this period of time. A total of 121 patients were investigated, being 80.2% females (female:male ratio=4:1), with higher frequency in mulatto individuals (64%), and the relapsing-remitting type (91.3%). Most patients (68.7%) had mild MS, and blacks were prone to worse prognosis compared to other patients.

Key words: multiple sclerosis, epidemiology, reference center.

RESUMO

A esclerose múltipla (EM) é doença auto-imune, desmielinizante e degenerativa que afeta o sistema nervoso central. Sua prevalência e seus aspectos clínicos variam de acordo com o continente estudado, sendo mais freqüente em caucasianos e indivíduos jovens entre a terceira e quarta décadas de vida. Dados epidemiológicos sobre o Brasil demonstram que a prevalência é variável, sendo mais freqüente nas regiões sul e sudeste que no norte e nordeste. O objetivo desse estudo é descrever as características clínicas e epidemiológicas da EM no Estado da Bahia, nordeste brasileiro. Assim, realizamos estudo de corte transversal durante o período de fevereiro a maio de 2005, no Núcleo de Apoio ao Pacientes com Esclerose Múltipla da Bahia, incluindo todos os pacientes consecutivos, com diagnóstico de EM, atendidos nesse período. Foi estudado um total de 121 pacientes, 80,2% do gênero feminino com uma relação de 4:1 com o gênero masculino, sendo observado maior freqüência de mulatos (64%) e da forma surto-remissão (91,3%). A maioria dos pacientes (68,7%) foi classificada como EM leve, sendo que os negros apresentaram indícios de pior prognóstico em relação aos outros pacientes.

Palavras-chave: esclerose múltipla, epidemiologia, centro de referência.

Multiple sclerosis (MS) is an autoimmune, demyelinating, degenerative disease that affects the central nervous system¹. Its etiology is still unknown, but it is assumed this is an interaction among genetic, infectious and environmental factors to favor its development². The types of MS are relapsing-remitting, primary progressive and secondary progressing. The prevalence of MS is variable. In Northern European countries and in North America, its prevalence is estimated in 300/100000, whereas in Africa and equatorial zones, the estimated prevalence is lower than 5/ 100000³.

Typically, Caucasians are affected the most by MS, and the lowest affected ethnical groups are blacks and orientals. This disease is more frequent in women (female: male ratio ranging from 1.2:1 to 5:1) compared to men³. Young adults aged 20 to 40 years are affected the most, and in developed countries MS is the main cause of disability for this age group, second to external causes¹.

National studies have shown great MS epidemiological variability over Brazilian states, due to the particular features of each population investigated. For Bahia, no studies so far have described the particulars of this disease, not withstanding the state's demographic data. Thus, the purpose of this study is to describe the clinical and epidemiological characteristics of MS patients who live in the state of Bahia.

METHOD

A cross-sectional study was held from February to May 2005 at Multiple Sclerosis Patient Support Center ("Núcleo de Apoio ao Paciente com Esclerose Múltipla" - NAPEM), within the Magalhães Neto Outpatient Clinic, Professor Edgar Santos University Hospital (HUPES), Federal University of Bahia (UFBA). All consecutive patients who came for a medical visit over the period of time of the study, with a confirmed diagnosis of MS based on the criteria by McDonald et al. (2001) established by a NAPEM physician were included.

Data were collected from a standardized clinical form by the study investigators. To prevent biases, training sessions on how to fill out the form were held.

The epidemiological variables were: gender, age at onset of disease, length of time with the disease, color of the skin, level of education. The clinical variables were the Kurtze scale (EDSS), which is validated to assess neurological impairment in MS patients, and the clinical manifestation of the disease.

After data collection, a databank was built, with the use of software SPSS v.9.0, and the presented variables were described by measures of frequency, dispersion, and central tendency (mean and median).

RESULTS

A total of 121 patients were included; of them, 97 (80.2%) were females, with a female: male ratio of 4:1. Mean age at onset was 31.1±11.02 years, being 31.46±10.70 for females, compared to 29.69±12.37 for males. For 11 patients (9.1%), their age at onset was under 18 years. In most patients, symptoms started between the second and fourth decade of life (Fig 1).

The relapsing-remitting clinical type was the most frequent one, with 91.3% of the sample, compared to 6.1% of the primary progressive and 1.7% of the secondary progressive type. The most frequent site of disease onset was the optical pathways (34.4%) and spinal cord (34.4%), followed by compromised telencephalon (19.4%), cerebellum (7.5%), and brainstem (4.3%) (Fig 2).

In our population, mulattos were affected the most (64%), followed by whites (27%), and blacks (9%). There were clinical differences among the groups; in our study the blacks were more clinically compromised on EDSS measurement compared to whites and mulattos (Table 1).

In terms of severity of the disease, mean EDSS score was 3.21±2.27, with a median of 3; a high proportion of patients had mild disease (68.4%), compared to 21.1% with moderate, and 10.5% with severe disease. In spite of the sample having only 10 patients with the progressive forms of the disease, a very low number, one could note the severity of the disease, as its mean EDSS score was 5.1±1.91, versus the relapsing-remission type, which had a mean EDSS score 2.91±2.14.

Mean of annual relapsing was 0.93±1.06 relapses/ year; it was higher in those younger than 18 years of age at onset of disease (2.0±2.08 relapses/year) versus those who were older than 18 years at onset (0.76±0.69 relapses/year).

As for immunomodulators, 93.3% of the patients used it actively. Rebif^® was used by 45.5% of the patients, followed by Copaxone^®, 23.3%; Betaferon®, 20.2%; and Avonex^®, 7.9%. Rebif^® was the first immunomodulator to be dispensed by the State of Bahia Health Secretariat.

Table 2 shows a comparison of this investigation with other published studies on the epidemiology of MS in the Brazilian states.

DISCUSSION

This investigation, carried out in the reference center for MS of the State of Bahia, showed that, in spite of MS being an urban disease, with well-defined diagnostic criteria, the medical and epidemiological features of the disease vary according to the geographical area under investigation, as we can see from the different Brazilian states^4-13. Thus, while we estimate a prevalence of less than 5% for the Northeastern region 5%^6,13, prevalence in the Southern and Southeastern regions range between 15% to 18%^4,5,7-12. On the other hand, the higher frequency of the optical pathways and the spinal marrow as the site of first symptoms observed in this study confirm data from other Brazilian authors, who point a higher proportion of Devic's disease among black-colored individuals, and Lana-Peixoto⁷ stressed out similarities with the Asian type. On the other hand, Arruda et al. observed a frequency of only 3.5% of Devic's disease in a study carried out in the State of Paraná, and they believe such low frequency is due to the small prevalence of blacks and orientals in their sample⁴. The few studies carried out in Africa showed that prevalence of MS is low in that continent^14-17; however, it increases among African descendants living in the United States, who have a smaller risk of developing MS compared to Caucasians¹⁸. This data show that there is possibly a gene protection factor among African or African-descendent populations for the onset of disease, which is less expressed in the North-American population due to gene mixing or environmental factors yet to be identified.

One aspect that should be mentioned is a possible selection bias in our sample, as many patients are referred to NAPEM for treatment, and access to a neurologist is easier for patients of the State's capital city. When we compare our sample to that of other Brazilian states, we see that, differently from the Southern and Southeastern regions, there is a big population of mulattos and blacks with MS in the Northeastern Region^4-13, which justifies large-scale epidemiological studies to determine differences among populations of all Brazilian regions.

Received 1 March 2006, received in final form 29 May 2006. Accepted 21 June 2006.

Dr. Ailton Melo - Avenida Magalhães Neto 735 / 802 - 41820-011 Savador BA - Brasil. E-mail:[e-mail]

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Publication Dates

• Publication in this collection
  11 Oct 2006
• Date of issue
  Sept 2006

History

• Received
  29 May 2006
• Accepted
  21 June 2006