Multiple sclerosis in Malta in 1999: an update. (Paper).

Objectives: To ascertain the prevalence of multiple sclerosis (MS) in the islands of Malta and compare it with a previous study undertaken 21 years earlier, when a remarkably low prevalence was found.

Method: Deaths with MS on the death certificate since the last study were reviewed. Sources of information about new patients were the Hospital Activity Analysis scheme, the MS Society of Malta, the records of the state hospitals, long stay private hospitals and nursing homes, lists provided by the state pharmacies, and magnetic resonance imaging, cerebrospinal fluid, and evoked response studies. Prevalence day was 1 January 1999. The Poser classification was used.

Results: Since 1978, 17 patients had died with a verified diagnosis of MS on the death certificate. They included all 10 deaths with MS from the original study and two immigrants. Fifty patients had clinically definite MS (CDMS) and 13 clinically probable MS (CPMS). The prevalence of CDMS was 13.2/100 000 (male 11.2, female 15.2). The prevalence of CDMS and CPMS combined was 16.7/100 000 (male 13.3, female 19.9). The annual incidence was 0.7/100 000. Twelve patients were found with CDMS among the 7213 immigrants resident in Malta (166/100 000). The expected rate was 1/100 000, determined at Maltese born rates. There were major changes in the population distribution during the 21 years between the two studies, with a big increase in the age groups with a high risk of MS. There is a longer expectation of life and the diagnosis in now made earlier.

Conclusion: Malta still has a low MS prevalence. In comparison with Sicily and other Mediterranean countries of Europe it offers an opportunity to ascertain the genetic and environmental factors responsible for the disease.

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In a study in Greater London and the West Midlands a high prevalence of multiple sclerosis (MS) was found among those discharged from hospital between 1960 and 1972 who were immigrants from Europe, with the exception of immigrants from Malta. In this study the calculated expected number of patients with MS born in Malta, at the England and Wales rate, was 10. However, no Maltese born patients were found. In contrast the number of patients with MS born in nearby Italy was little different from the expected number. (1 2)

The absence of hospitalised patients with MS among immigrants from Malta to England prompted a study in the islands of Malta and Gozo in 1975-8. (3) Malta has had a medical school since 1676. English is commonly spoken and medical records are kept in English. Patients who were suspected of having MS were frequently sent to England for further investigation. Despite an intensive search in the Maltese islands on prevalence day, 1 January 1978, only 14 were found with a diagnosis of MS. one of whom had neuromyelitis optica (Devic's syndrome). Eleven were living in Malta and three in the nearby island of Gozo. A further patient with MS was overseas at the time of the study. Three had a diagnosis of possible MS.

Nine of the 14 patients with MS in the previous study had been investigated at London teaching hospitals. None of the patients with MS were related. During the 10 years (1967-76) MS was recorded as a cause of death on only six death certificates in Malta, (4) and in five of these the history and clinical findings confirmed the diagnosis. The sixth was incorrectly certified.

Concurrently with the 1975-8 study on MS prevalence in Malta a similar study was undertaken in the city of Enna in central Sicily, where 15 patients with MS were found in a population of 29 189, or 53/100 000. (5) The high prevalence in Enna in comparison with Malta was subsequently confirmed in three other cities of Sicily--Agrigento, (6) Monreale, (7) and Caltanisetta (8)--as well as in the Republic of San Marino. (9)

The present study aimed at ascertaining the changes in the prevalence of MS in Malta since the previous study and to ascertain whether the low MS prevalence found in Malta in 1978 was persisting.

METHOD

In Malta medical records are well kept. A national identification numbering system was started in 1978 and is now fully installed. The last two numbers on the identification code are the date of registration, which is generally the year of birth. Patients receive free medical care at the state hospitals: St Luke's Hospital in Malta and the General Hospital in Gozo. They collaborated with the study, as did the long stay Sir Paul Boffa Hospital and St Vincent De Paule Residence, 12 private nursing homes, and 20 homes with a total of 703 residents under the aegis of the church.

Patients suspected of having MS were frequently …