Prevalence and Incidence of Multiple Sclerosis in the City of Biancavilla

Our plain-English summary of Prevalence and Incidence of Multiple Sclerosis in the City of Biancavilla, by F. Patti, C. Caserta, S. Colandonio, et al (Neuroepidemiology, 2019).

The study

• Authors: F. Patti, C. Caserta, S. Colandonio, M.L. Iudica, D. Maimone, S. Lo Fermo, E. D'Amico, C. Chisari, F. Mayer, N. Vanacore
• Journal: Neuroepidemiology
• Published: 2019;53(1-2):108-114
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: It is common that the epidemiology of multiple sclerosis (MS) varies with geography and ethnicity. Recent studies show a continuous growth of incidence and prevalence in Sicily, despite the controversial "latitude gradient theory."

Objectives: The aim of our study is to ascertain incidence and prevalence rates of MS in the city of Biancavilla, Sicily, Southern Italy.

Method: Case ascertainment approach and a clinical database collecting data of MS cases to Biancavilla, according to McDonald 2011 and Thompson 2018 criteria, from 1992 to 2018, have been used to the study. We further collected information regarding the familiarity of patients with Mesothelioma, highly incident in this geographic area.

Results: The results showed an increase of the mean annual incidence for the period 2012-2018 (16.8/100,000) compared to 1992-1996 (4.5/100,000), and a standardized incidence ratio of 1.41 (95% CI 0.74-2.45). On December 31, 2018, 70 patients suffering from definite MS and living in Biancavilla yielded a crude prevalence of 292.3 per 100,000 (198.2/100,000 for men; 380.7/100,000 for women) with a standardized morbidity ratio of 2.3 (95% CI 1.8-2.9).

Conclusions: Our data confirmed Biancavilla is an area at high risk for MS, ascribable to increased survival, improved ascertainment, or maybe related to a genetic or environmental risk. At the time, any relation with mesothelioma was excluded.

© 2019 S. Karger AG, Basel.

In plain English

This study counted multiple sclerosis (MS) cases in Biancavilla, Sicily, Italy, from 1992 to 2018. Nearby rock contains an asbestiform fiber, fluoro-edenite, which the authors describe as linked to pleural and peritoneal mesothelioma. The study did not measure anyone's fiber exposure. Of 74 resident cases identified, 3 had died and 1 had an unconfirmed diagnosis, leaving 70 living residents with definite MS. On December 31, 2018, prevalence was 292.3 per 100,000 among 23,948 inhabitants (198.2 for men, 380.7 for women). Compared with 2004 rates in Catania, Biancavilla had 2.3 times the expected number of cases (95% CI 1.8–2.9). Yearly new cases rose from 4.5 per 100,000 in 1992–1996 to 16.8 in 2012–2018. For 2002–2006, new cases were 1.41 times those expected (95% CI 0.74–2.45), which was not statistically significant. A questionnaire found no pleural or peritoneal mesothelioma among patients' relatives. The authors took this as evidence against a link with fluoro-edenite exposure. They concluded that Biancavilla has high MS rates and called for a case-control study. They noted reporting delay and small numbers as possible limitations.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Population-based study of MS prevalence and incidence using case ascertainment from multiple sources, 1992–2018, with a questionnaire on personal and family medical history
• Who was studied: Residents of Biancavilla, Sicily, Italy, with MS. The population on the prevalence day, December 31, 2018, was 23,948 (11,602 men and 12,346 women). 74 cases were identified and 70 were included (3 had died and 1 had an unconfirmed diagnosis).
• Exposure: No individual exposure was measured. The study area lies near a deposit containing the asbestiform fiber fluoro-edenite, which the authors describe as linked to pleural and peritoneal mesothelioma. Patients were asked about mesothelioma in their families.
• Main results:
  • 74 cases resident in Biancavilla were identified: 25 men and 49 women. 70 were enrolled. 3 had died by the prevalence day, and 1 man had an unconfirmed diagnosis (possible MS under Thompson criteria, clinically isolated syndrome under McDonald criteria).
  • Prevalence on December 31, 2018 (Thompson criteria, 70 cases): 292.3 per 100,000 overall, 198.2 for men, 380.7 for women. Using McDonald criteria (69 cases), it was 288.1 per 100,000.
  • Compared with age- and sex-specific rates in Catania from 2004, Biancavilla's 2018 standardized morbidity ratio was 2.3 (95% CI 1.8–2.9): 70 observed cases against 30.4 expected.
  • Average annual incidence in 2012–2018 (Thompson criteria) was 16.8 per 100,000: 22.1 for women and 11.1 for men.
  • Incidence (Thompson criteria) was 4.5 per 100,000 in 1992–1996, 10.7 in 1997–2001, 9.6 in 2002–2006, 13.6 in 2007–2011 and 16.8 in 2012–2018.
  • For 2002–2006, 11 new cases were observed against 7.8 expected from Catania 2000–2004 rates. The standardized incidence ratio was 1.41 (95% CI 0.74–2.45), which was not statistically significant.
  • The median age at MS onset was 28.3 years.
  • The questionnaire found no pleural or peritoneal mesothelioma in relatives of the MS patients.
• The authors' conclusion: The authors concluded that Biancavilla has high MS prevalence and incidence. They suggested longer survival, improved diagnosis, or genetic or environmental factors as possible explanations. They wrote that the absence of mesothelioma among patients and their families argued against a fluoro-edenite link, and that a population case-control study is needed.
• Limitations the authors state:
  • A diagnostic reporting delay bias cannot be excluded.
  • Changes in the women-to-men ratio could reflect random variation, because the population studied was small.
  • Late-onset cases may have been underestimated because MS is hard to tell apart from diseases of aging.
  • A population case-control study is needed to assess gene-environment factors.

Topics

Medical terms in this study, explained in our Lexicon: Biancavilla, Epidemiology, Mesothelioma, Standardized Incidence Ratio (SIR).

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