Largest Population Study ever

Posted - May 2009 in Research Highlights

 HSP rate 7.4 per 100,000 population

 

A Norwegian study of more than 2.5 million people has found an HSP prevalence rate of 7.4/100,000 of population – a higher rate, but in the same range as previous studies.  No differences in rate relating to gender were found.  Average age at onset was 24 years old.

Extrapolated to the Australian population, this translates to about 1,750 HSPers, and to a global total of over half-a-million (546,000).

(figure updated November, 2015).  

The Study

A study was performed in southeast Norway, between January 2002 and February 2008, to identify subjects with hereditary ataxia and hereditary spastic paraplegia, and to estimate the prevalence of these disorders.

Patients were recruited through colleagues, families, searches in computerized hospital archives and the National Patients’ Association for Hereditary Ataxia and Spastic Paraplegia. Strict criteria were used for inclusion of familial and isolated subjects. A project neurologist examined all index subjects and clinical and genetic data were registered.

The source population on January 1, 2008 was 2.63 million and the prevalence day was set as February 1, 2008.  171 subjects from 87 unrelated families with hereditary ataxia and 194 subjects from 65 unrelated families with hereditary spastic paraplegia were included.


Results

The total prevalence was estimated at 13.9/100 000.

Hereditary ataxia prevalence in the region was estimated at 6.5/100 000: 4.2/100 000 for autosomal-dominant and 2.3/100 000 for autosomal recessive, 0.15/100 000 for Friedreich’s ataxia and 0.4/100 000 for ataxia telangiectasia.

Hereditary spastic paraplegia prevalence was 7.4/100 000: 5.5/100 000 for autosomal dominant-hereditary spastic paraplegia, 0.6/100 000 for autosomal recessive-hereditary spastic paraplegia and 1.3/100 000 for isolated subjects.

Marked differences were found in the frequencies of hereditary ataxia subtypes compared with other countries, while those of the most common autosomal dominant-hereditary spastic paraplegia genotypes, SPG4, SPG3 and SPG31, were similar to those previously reported.  Clear variations between age groups and counties were observed, but no gender differences.

Mean age on prevalence day was 48 years, mean age at onset was 24 years. We present the largest population study performed on hereditary ataxia and hereditary spastic paraplegia prevalence and report a higher prevalence than expected. Better inclusion criteria and multiple search strategies may explain the observed differences.

SOURCE:         Brain. 2009 Mar 31.

Prevalence of hereditary ataxia and spastic paraplegia in southeast Norway: a population-based study.

Erichsen AK, Koht J, Stray-Pedersen A, Abdelnoor M, Tallaksen CM.

Department of Neurology, Ullevål University Hospital, Oslo, Norway.