Epidemiology of hereditary ataxias in Spain: hospital discharge registry and population-based mortality study

Hereditary ataxias (HA) comprise a group of genetically heterogeneous rare diseases. As important public health problems to be monitored, this study analyses the morbimortality of HA in Spain.

Data were extracted from the national death index (1981-2008), using the International Classification of Diseases (ICD) 9th revision code 334 until 1998, and 10th revision code G11 from 1999 onwards. ICD-9 codes were then selected from the national discharge dataset (1998-2007). Age-adjusted morbidity and mortality rates were obtained by gender and 5-year period.

Of the 610 HA deaths from 1981 to 2008, 277 corresponded to Friedreich's ataxia (45.4%) and 333 (54.6%) to other and unspecified ataxias (non-Friedreich group). Both groups showed an increase in mortality trend, which was more pronounced in males from 1985-1989 to 1990-1994. Geographical distribution of mortality revealed higher risk for males, mainly in the north of Spain. A total of 5,341 HA hospitalisations were identified from 1998 to 2007. The average annual age-adjusted hospitalisation rate was 1.19 per 100,000 population, with a rising trend.

This increase in morbidity and mortality, coupled with the slight interprovincial differences, indicate that more attention should be paid to these rare diseases by public authorities and society alike.