Amyotrophic lateral sclerosis in Sardinia, insular Italy, 1995–2009

Recent genetic studies suggest a Sardinian type of amyotrophic lateral sclerosis (ALS). Thus, ALS incidence, prevalence and survival were investigated in a large population of Sardinians aimed to disclose population-specific patterns and their temporal changes. This is a population-based incidence and prevalence study in northern and central Sardinia, insular Italy (over 700,000 population). Incidence rates were computed for the time interval 1995–2009 and by quinquennia. Prevalence was computed for prevalence days 31 December 2004 and 2009. Onset-based survival for 1995–2009 is also reported. All ALS patients (El Escorial Criteria) in the study area were retrospectively included. The ALS crude incidence from 2005–2009 was 2.5 (95 % CIs: 0.1, 4.9), 3.4 in men and 1.6 in women. Onset occurred most often between the age of 65–74 years in men and 55–64 years in women. The ALS incidence tended to increase over the period 1995–2009. The mean age at onset was 61.7 years with no difference based on gender, varying significantly from 59.9 years in 1995–1999 to 63.9 years in 2005–2009. On December 31, 2009, the ALS crude prevalence was 10.8 per 100,000 (95 % CIs: 8.6, 13.1), 13.8 in men and 8.0 in women, whereas it was 6.3 per 100,000 (95 % CIs: 4.1, 8.6) on December 31, 2004 (M:F ratio of 0.95). Mean survival from onset was 37.0 months, with no difference based on gender, and a tendency to decrease during the period 1995–2009, in relation to type and age of onset. The population-based incidence and prevalence data of ALS in Sardinians indicate an increase of the disease occurrence over the past 40 years, providing support for a population-specific variant of ALS in Sardinia.