Prevalence of multiple sclerosis in key cities of Brazil: a study in Passo Fundo, Southern Brazil

BACKGROUND

To improve the comparability of multiple sclerosis (MS) prevalence across Brazilian regions, the Brazilian Committee for Treatment and Research in MS has implemented a standardized approach to assess the prevalence of the disease in five key cities, which were deemed representative of their regions in terms of socio-geographical features and where in-person revision of each case was feasible.

OBJECTIVE

To report the point-prevalence of MS in Passo Fundo, one of the key cities in Southern Brazil.

METHODS

We sought to identify all MS patients who were living in Passo Fundo on July 1st, 2015. The primary source for case ascertainment was records from the offices of neurologists and neurosurgeons practicing in the city. Multiple secondary sources were used to maximize identification of cases. All patients underwent in-person review of the diagnosis by a panel of neurologists with experience in MS.

RESULTS

We identified 52 MS patients living in Passo Fundo on July 1st, 2015. The point-prevalence rate for MS was 26.4/100,000 population (95% confidence interval, 19.7 to 34.6/100,000). Among the MS cases, 42 (80.8%) were female, for a sex ratio of 4.2:1. Forty-six cases (88.5%) were categorized as relapsing-remitting MS, and the remaining 6 cases, as secondary progressive MS (11.5%). Other epidemiological and clinical features were comparable to national and international MS populations.

CONCLUSIONS

The prevalence of MS in Passo Fundo is one of the highest reported in Brazil so far. Studies in other key Brazilian cities, using the same methodology, are currently being carried out.

Prevalence of multiple sclerosis in key cities of Brazil. A study in Joinville, Southern Brazil

BACKGROUND

The Brazilian Committee for Treatment and Research in Multiple Sclerosis (BCTRIMS) has launched an initiative to determine the prevalence of multiple sclerosis (MS) in Brazil, based on key cities deemed representative of their regions in terms of demographic and environmental features.

OBJECTIVE

To investigate the prevalence rate of MS in Joinville.

METHODS

We reviewed the medical records of all patients who lived in Joinville and met the 2010 McDonald's diagnostic criteria revised for MS on the prevalence day (March 11, 2016). Potential MS patients included individuals treated by all practicing neurologists in the city and the ones found in patients' association and the database of the Municipal Department of Health. Advertisements about the survey were also broadcast on radio and television. Patients who were not living in Joinville on the prevalence day were excluded. All potential MS patients were invited to an in-person diagnostic review, carried out by a panel of experienced neurologists with special expertise in MS on March 11, 2016.

RESULTS

The MS prevalence rate was 13.5 per 100,000 inhabitants (95% confidence interval [95%CI] 12.9-14.0/100,000). A total of 51 (66.2%) participants were females, and 26 (33.7%) were males (female to male ratio=1.9:1). Out of the 77 patients, 73 (94.8%) were Caucasians, and four (5.1%) were mixed-race.

CONCLUSIONS

Despite its latitude location and European colonization, the prevalence rate was below expectation. The intense internal migration from regions with lower MS prevalence rates to Joinville may have played a role in attenuating the increased risk of MS associated with latitude gradient and European ancestry. Prevalence studies in other cities from Southern Brazil with no significant internal migration and taking part in this broad project may clarify this issue.