EPIDEMIOLOGY OF MULTIPLE SCLEROSIS IN LATIN AMERICA: CRITICAL ANALYSIS OF THE LITERATURE
Authors: Thomas R. Einarson, PhD 1; Basil G. Bereza, MSc (PhD Cand.) 1; Márcio Machado, PhD 2.
1
Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto ON, Canada.
2
Biogen Idec, São Paulo SP, Brazil.
INTRODUCTION
RESULTS
203 articles reviewed in full; 88 were rejected and 115 analyzed
• Rates of multiple sclerosis (MS) vary around the world, depending on genetics/
race, geography and possibly ultraviolet radiation.
• 23% did not specify diagnostic criteria; of those that did specify: 66% used the
criteria of Poser, 48% used McDonald, 5% Schumacher, and 8% other (many
used >1, hence >100%).
• 59% were full peer-reviewed articles, 41% were abstracts.
• Accurate estimates of incidence and prevalence are necessary for estimating the
burden of disease as well as planning and apportioning healthcare services.
• The purpose of this research was to summarize rates of prevalence, incidence
and types of MS in Latin America.
First publications:
• First case series of MS described in Cuba by Estrada 1965.
• First population based study in Latin America in Mexico in 1970 by Alter &
Olivares.
• First clinical description of MS cases in South America was in Chile by Alvarez
1992.
METHODS
• Latin America was defined as the 24 countries identified by the World Health
Organization (see Table 1).
• Acceptable studies included peer reviewed articles and abstracts of
presentations made at scientific conferences.
Table 1 presents the numbers of articles and their countries of origin
• Fourteen countries (58%) generated all of the research.
• These countries contain 87% of the population of Latin America.
• The largest 3 countries (Brazil, Argentina and Mexico) produced 70% of all
articles.
• Ten countries (42%) produced no articles.
• All languages accepted; no restriction on date of publication.
• Studies must have calculated cross-sectional or longitudinal rates of prevalence,
incidence, and/or clinical epidemiology (types of MS).
• Diagnosis could be made using any acceptable criteria, such as Schumacher,
Poser, McDonald, or by neurologist examination.
Table 2 summarizes the reported rates of prevalence of multiple sclerosis
• Types of MS were defined based on symptoms and presentation: relapsing
remitting MS (RRMS), primary progressive (PPMS), secondary progressive
(SPMS), progressive relapsing (PRMS).
• Average prevalence = 13.9 per 100,000 (Range: 1.4 to 52 per 100,000)
• Majority female (72%).
• Some authors perceived an increase in prevalence over time.
• 3 studies found no latitude gradient within countries (Chile, Argentina).
• Searches made on Medline, Embase, LILACS, and Scielo from inception to the
end of 2013.
Table 3 summarizes the reported rates of incidence of multiple sclerosis
• Hand searches of reference lists from retrieved articles were also carried out.
• Very few studies (Total = 8; 1132 cases).
• Wide range of rates from 0.15 to 1.8 per 100,000 per year.
• Estimates were based on small populations; largest study with sample of 721,
otherwise samples ranged from 12-92).
• Data were tabulated and analyzed descriptively.
Table 1. Distribution of studies by country and outcome examined
Country
Primary outcome examined
Prevalence
Incidence
Clinical
5
2
11
Argentina
Table 4 summarizes clinical epidemiology
Total
• Data obtained from 10 countries (42% of those in Latin America).
• Three countries supplied 75% of the studies.
• 72% of sample with relapsing remitting MS.
18
Bolivia
0
Brazil
16
Chile
1
Colombia
2
41
57
1
2
4
0
4
6
Costa Rica
0
Cuba
1
4
DISCUSSION
5
Dominican Republic
0
Ecuador
2
2
El Salvador
0
French Guiana
0
Guadeloupe
1
2
0
Haiti
0
Honduras
0
2
Mexico
5
Results were not conclusive
• Prevalence rates vary widely; reasons for variance were not often explored.
• Prevalence rate lower than the world average of 30 per 100,000.
• Incidence rates lower than the global average of 2.5 per 100,000 per year.
• Pattern of MS types similar to what is found globally.
• No data of any kind from 42% of countries; those without data were the poorest.
• Very few studies examined incidence of MS in Latin America; none from (Brazil).
3
Guatemala
Martinique
2
4
5
10
Nicaragua
0
Panama
1
1
Quality of reporting was often poor
2
Paraguay
• Reporting of results was often incomplete, with missing data common.
• 41% of papers appeared only as abstracts.
0
Peru
1
Puerto Rico
1
1
Uruguay
2
2
Venezuela
1
2
Multiple countries
PND15
3
3
4
1
1
Total
41
8
72
121
Countries
14
6
8
n/a
Limitations:
• A few studies could not be located.
• Some studies examined very small populations.
• Very little information exists over time in the same populations.
• Many populations have never been studied.
Table 2. Reported rates of the prevalence of multiple sclerosis in Latin America
Average age
Prevalence (cases/100,000 population)
At diagnosis
At assessment
Duration
(years)
66%
32.6
38.8
7.7
17.7
12.0
25.6
16
73%
30.2
36.5
5.8
13.6
1.4
30.0
Chile
1
68%
NR
NR
NR
1.9
NR
NR
Colombia
2
71%
35.2
40.2
5.5
3.2
1.5
6.0
Cuba
1
72%
32.0
44.0
12.0
27
NR
NR
Ecuador
2
65%
32.5
38.3
5.9
1.4
0.7
5.0
Guadeloupe
1
86%
NR
37.4
NR
8.5
5.4
11.6
Martinique
2
77%
31.2
41.1
9.8
14.6
10.4
25.9
Mexico
5
70%
29.7
35.4
5.7
8.9
0
30.0
Panama
1
NR
34.3
43.0
8.7
5.2
1.6
8.9
Peru
1
NR
NR
NR
NR
7.7
7.1
8.3
Puerto Rico
1
NR
NR
NR
NR
52
NR
NR
Uruguay
2
NR
NR
NR
NR
30
NR
NR
Venezuela
1
74%
NR
39.0
NR
6.9
NR
NR
Total
41
72%
31.5
38.7
7.7
13.9
1.2
52.0
Country
Studies
% Female
Argentina
5
Brazil
Average
Minimum
Maximum
NR = not reported
Table 3. Studies of the incidence of multiple sclerosis in Latin America
Country
Author
Period of data
collection
Population or
subgroup
% female
Age
Cases
Base population
Incidence
per 100,00 (95% CI)
Cristiano 2010
1992-2007
Italian Hospital, Buenos
Aires
61%
35.7
18
145,000
1.76 (1.1-2.8)
Melcon 2008
NR
Patagonia
65%
41.6
72
417,666
1.4 (NR)
Díaz 2012
2001-2006
National population
64%
39
721
6,857
0.9 (0.75-1.05)
Cabre 2005
1992-2002
National population
89%
NR
12
340,000
0.7 (0.6-0.7)
Cabre 2009
1992-2007
National population
81%
NR
38
340,000
0.75 (0.63-0.87)
Cabre 2005
1992-2002
National population
89%
NR
35
343,000
2.0 (1.4-2.6)
Cabre 2009
1992-2007
National population
81%
NR
92
343,000
1.80 (1.63-1.97)
1990-1999
National population
NR
NR
65
NR
0.15 - 0.40*
2000-2005
National population
NR
NR
79
NR
0.28 - 0.61*
Overall
76%
38.8
1132
Studies
Argentina
2
Chile
1
Guadeloupe
2
Martinique
2
Panama
1
Total
8
Gracia 2009
*Reported a range, depending on assumptions; NR, not reported.
Table 4. Clinical epidemiology of multiple sclerosis in Latin America
Studies
Cases
% female
Age at onset
Age at
assessment
Duration (years)
Average EDSS
Argentina
11
1,737
60%
35.8
42.7
12.2
Brazil
52
12,837
73%
32.9
39.8
Colombia
5
623
69%
36.0
Cuba
5
583
76%
Ecuador
2
203
Martinique
3
Mexico
Country
Type of multiple sclerosis
RRMS
PPMS
SPMS
PRMS
2.4
72%
26%
12%
2%
7.9
3.1
78%
16%
13%
2%
40.1
8.2
NR
70%
16%
12%
1%
32.0
41.8
12.0
4.5
73%
17%
9%
2%
65%
32.5
38.3
5.9
NR
68%
8%
19%
5%
355
79%
32.3
39.9
8.6
NR
66%
9%
13%
11%
6
975
74%
26.5
35.6
6.6
NR
57%
11%
21%
8%
Panama
1
153
NR
34.3
43.0
8.7
2.7
78%
10%
12%
0%
Peru
2
67
66%
29.3
35.7
6.4
3.5
49%
20%
13%
95%
Venezuela
5
2000
68%
NR
21.9
NR
NR
82%
3%
9%
0%
Overall
92
19,533
70%
32.4
37.9
8.5
3.2
72%
14%
12%
2%
EDSS, Expended Disability Status Score; PPMS, Primary Progressive Multiple Sclerosis; PRMS, Progressive Relapsing Multiple Sclerosis; RRMS, Relapsing Remitting Multiple Sclerosis; SPMS, Secondary Progressive Multiple Sclerosis.
CONCLUSIONS
• The prevalence of 13.9 cases of MS per 100,000 in Latin America is low to
medium, and lower than the world average.
• The incidence is also lower than the world average.
• Clinical presentation of MS is similar to patterns in the rest of the world.
• Much information related to epidemiology is lacking; there is a need for high
quality studies from all areas of the region.
The present research was funded by Biogen Idec. Presented at the ISPOR 17th Annual European Congress, in Amsterdam, The Netherlands. Monday, 10 November 2014.