Keywords:
Prevalence - multiple sclerosis - neuroogy
Palavras-chave:
Prevalência - esclerose múltipla - neurologia
Multiple sclerosis (MS) is an inflammatory, demyelinating and degenerative disease
of the central nervous system, of unknown etiology but supposedly associated with
the interaction of genetic, infectious and environmental factors, more often affecting
young adults, Caucasians and females. The disease is characterized by repeated episodes
of neurological symptoms affecting several parts of the central nervous system, called
functional systems, resulting in a great variability of symptoms, which typically
include cognitive, sensory and motor alterations[1]. The prevalence of MS varies considerably worldwide. Kurtzke has designated a three-zone
global prevalence rating: high (30–80 per 100,000), medium (5–25 per 100,000), and
low zones (< 5 per 100,000)[2]. Wade, in 2013, proposed a new global MS prevalence scale with five categories:
very high (170–350 per 100,000), high (70–170 per 100,000), medium (38–70 per 100,000),
low (13–38 per 100,000), and very low (0–13 per 100,000)[3]. It was estimated that Brazil was in the medium zone by Kurtzke, and in the low
zone by Wade.[2],[3] Brazil is a country covering a very large area, located between latitudes 5°16´20”N
and 33°44´42”S, and with five geographic regions: north, south, midwest, southeast
and northeast, with widely diversified geographic, demographic and population aspects
between the regions[4]. The crude prevalence rates of MS found in studies conducted in Brazil ranged from
1.36/100,000 inhabitants in Recife (northwest region)[5] to 27.2/100,000 inhabitants in the city of Santa Maria, Rio Grande do Sul (south
region)[6]. The only study that used the capture-recapture method was conducted in Volta Redonda,
Rio de Janeiro (southwest region), and found 30.7/100,000 inhabitants, the highest
prevalence in Brazil[7]. The aim of the present study was to determine the prevalence of MS in Goiânia,
a city located in the midwest region of Brazil, using multiple sources of case ascertainment.
METHODS
Study site
Goiânia is capital of the state of Goiás, located in the midwest region. It is in
the heart of Brazil, 209 km from the federal capital, Brasília, and is almost equidistant
from all other Brazilian states[8] ([Figure 1]). It is the second most populous city in the midwest region, being surpassed only
by Brasília. Its estimated population was 1,430,697 inhabitants in 2015. Goiânia is
the sixth largest city in Brazil, covering an area of 728.8 km2, lying near the parallel 16°40´43” south and the meridian 49°15´14” west. The Municipal
Human Development Index in Goiânia is 0.832, which is considered to be high by the
United Nations Development Program. The longevity index is 0.751 (the overall Brazilian
index is 0.638). Goiânia is a multiracial city, having a mixed population, comprising
white (48%), brown (44%), black (5.68%), indigenous (0.16%) and yellow (1.68%) people[4],[8].
Figure 1 Location of Goiânia in the state of Goiás, Brazil[8].
The day of MS prevalence determination was December 31, 2015.
Ethics
The study was approved by the committee of ethics and research. CAAE: 59067616.2.0000.5083.
Ascertainment of cases of MS
The tracking was conducted via three sources ([Figure 2]).
Figure 2 Venn diagram with three sources to gather information on MS patient prevalence. S1
- Dispensing center of high-cost medication, S2 - Centers of reference in the treatment
of patients with MS (Hospital das Clínicas/Hospital Geral de Goiânia), S3 - Private
neurologists.
Patients were screened through the International Code of Diseases (ICD 10): G35. A
basic questionnaire for the standardized collection of data was prepared. All data
were collected from medical records, and the informed consent form was dispensed with.
All patients were alive on December 31, 2015, the day of the prevalence study.
Classifications and definitions
The MS had been previously diagnosed by the attending physician of each patient. To
be included in the study, all diagnoses of MS must had been defined with the Poser
diagnostic criteria[9] and/or the McDonald criteria[1] and the patients had to reside in the city of Goiânia.
Data analysis
Crude prevalence was calculated as the number of MS patients divided by the total
number of individuals living in Goiânia in Decer, 2015. An analysis of simple linear
Spearman's correlation for quantitative variables was performed. Analyses were performed
using the SPSS software, version 25.0 for Windows[10].
RESULTS
According to the latest demographic census carried out in Brazil in 2010, the population
of Goiânia was 1,302,001 inhabitants, of whom 681,144 were women and 620,857 were
men. By 2015, the estimated population was 1,430,697[8],[11].
The study found 318 cases of people with MS residing in Goiânia on the day of the
prevalence study (12/31/2015), representing a crude prevalence of 22.2/100,000 inhabitants.
The distribution of patients with MS according to socio-demographic factors and clinical
characteristics are described in [Figure 3] and [Table 1].
Figure 3 Year of diagnosis.
Table 1
Clinical and demographic characteristics of patients diagnosed with MS in the city
of Goiânia, 2015.
|
Clinical and demographic characteristics of patients
|
f
|
%
|
|
Sex
|
|
|
|
Male
|
74
|
23,3
|
|
Female
|
244
|
76,7
|
|
Total
|
318
|
100,0
|
|
Ethnicity (self-reported)
|
|
White
|
230
|
72.3
|
|
African
|
67
|
21.6
|
|
No information
|
21
|
6.60
|
|
Total
|
297
|
100.0
|
|
Clinical form
|
|
Relapsing-remitting (RRMS)
|
276
|
86.2
|
|
Secondary progressive (SPMS)
|
27
|
8.5
|
|
Primary progressive (PPMS)
|
1
|
0.9
|
|
No information
|
14
|
4.4
|
|
Total
|
304
|
100.0
|
|
Source 1 – Drug dispensing pharmacy
|
|
No
|
69
|
21,7
|
|
Yes
|
249
|
78,3
|
|
Total
|
318
|
100,0
|
|
Source 2 – Reference centers for MS treatment
|
|
No
|
233
|
73,3
|
|
Yes
|
85
|
26,7
|
|
Total
|
318
|
100,0
|
|
Source 3 – Neurologists
|
|
No
|
217
|
68,2
|
|
Yes
|
101
|
31,8
|
|
Total
|
318
|
100,0
|
|
Degree of disability
|
|
No disability
|
103
|
32,4
|
|
Mild disability
|
91
|
28,6
|
|
Moderate disability
|
80
|
25,2
|
|
Severe disability
|
28
|
8,8
|
|
No information
|
16
|
5,0
|
It is important to emphasize the limitations of the study, especially the fact that
it was a retrospective study.
DISCUSSION
In the city of Goiânia, the prevalence of MS was 22.2/100,000, on December 31, 2015.
In a literature review[11] evaluating the MS prevalence in Brazil as a whole, 19 studies were found, out of
which 13 studies were carried out in cities in the southeast[12],[13],[14],[15],[16],[17],[18],[19],[20],[21],[22],[23],[24], two in the southern region[6],[25], two in the midwest[26],[27] and one in the northeast[5].
Great variability was found in the values of maximum and minimum prevalence rates
in the prevalence studies conducted in the country. There was an overall prevalence
of 8.69 (95%CI 6.0–12.6) per 100,000 inhabitants. Regarding the methodologies employed,
all the Brazilian studies adopted a cross-sectional design, using raw data from sources
such as hospitals, information from neurologists, MRI services, patients’ associations,
reference centers and high-cost pharmacies. What did vary in these studies was the
number of sources used by each author.
Most authors used more than one source for the data collection. Brazil covers a large
area, which diversifies geographic, demographic and historical aspects of the regions
and the Brazilian population.
In the midwest region there were only two studies of MS prevalence. The first study
was conducted in Brasília, Federal District, from 1999 to 2003, and the authors found
a prevalence of 5.85/100,000[26]. The second study was undertaken in the western region, in the city of Cuiabá, Mato
Grosso, and showed a prevalence of 4.41/100,000 in 2002[27].
The methodology was similar in our study and the Cuiabá study (information from various
sources). There was no difference in the studies in Brasília, Cuiabá and Goiânia for
sex and ethnicity. White ethnicity was predominant and the calculation of the sex
ratio indicated a greater predisposition of females to contract MS, corroborating
most epidemiological studies in Brazil ([Table 2]).
Table 2
Clinical and demographic characteristics of patients with MS in the midwest region,
Brazil (%).
|
Varialble
|
Brasília
|
Cuiabá
|
Goiânia
|
|
Female sex
|
77.5
|
74.0
|
76.7
|
|
White ethnicity
|
75.7
|
74.0
|
72.3
|
|
Clinical form
|
|
Relapsing-remitting
|
90.6
|
69.5
|
86.2
|
|
Secondary progressive
|
4.6
|
21.7
|
8.5
|
|
Primary progressive
|
3.9
|
8.6
|
0.9
|
|
No information
|
0.9
|
0.2
|
4.4
|
Analyzing the clinical form of MS, we observed a similarity of the present study with
the results from Brasília (90.6% relapsing-remitting MS), while in Cuiabá 69.5% had
the relapsing-remitting form.
We found a significant increase in the number of diagnoses since the year 2005 ([Figure 3]), and most Brazilian studies conducted after the year 2000 also showed a higher
prevalence of MS. This increased prevalence can be attributed to the creation of specialized
nuclei for the MS patients’ care, better training of neurologists in neuroimmunology,
and the introduction of MRI services ([Figure 3]).
In conclusion, we expect to contribute with this descriptive epidemiological study
of MS in Goiânia, Goiás, Brazil, and encourage researchers to develop further studies
on this disease in different regions of Brazil as there is epidemiological evidence
indicating an increased prevalence of multiple sclerosis in areas previously considered
to have a low prevalence, as in the case of Brazil in Latin America.
