Epidemiology and etiology of autistic spectrum disorders difficult to determine

The incidence of diagnosed autism spectrum disorders in Finland

BACKGROUND

Previous reports indicate an increase in incidence of autism spectrum disorders (ASD).

AIMS

First, to assess the incidence of diagnosed ASD in children born between 1996 and 1998, based on nationwide inpatient and outpatient register information. Second, to investigate the incidence rate over time of diagnosed ASD and specifically childhood autism, Asperger's syndrome and pervasive developmental disorder (PDD-NOS) in children born between 1987 and 1998.

METHODS

This is population-based cohort study with children born in Finland between 1 January 1987 and 31 December 2005; a total of more than 1.2 million children. Children were identified in the Finnish Hospital Discharge Register, and the reported diagnoses were based on the International Statistical Classification of Diseases (ICD-10, ICD-9).

RESULTS

The annual incidence rate of diagnosed ASD based on inpatient and outpatient register data was 53.7 per 10,000 (95% CI 50.4-57.2). Incidence was 82.6 per 10,000 in boys and 23.6 per 10,000 in girls, yielding a sex ratio (boys:girls) of 3.5:1. We report an eightfold increase in the incidence rates in children of diagnosed ASD and specifically in childhood autism, Asperger's syndrome and PDD-NOS and born between 1987 and 1992 based on inpatient register information.

CONCLUSIONS

Increased awareness of ASD, more precise diagnostic criteria and changes in practice for diagnosing autism may have had a substantial effect on the increased incidence of inpatient treated ASD cases from 1987 to 1992. Between 1992 and 1998, the incidence rate based on inpatient and outpatient service use remained rather stable.

Diagnosticando o transtorno autista: aspectos fundamentais e considerações práticas

Tendo como base modelos de prática diagnóstica implementados em outros países, o objetivo do artigo é oferecer uma revisão geral acerca do que vem a ser o transtorno autista e dos fatores críticos que devem ser considerados durante o processo diagnóstico. São discutidos aspectos dos critérios diagnósticos e também das comorbidades, incidência, etiologia e diretrizes para a prática diagnóstica. Tais diretrizes incluem formas de exploração de sintomas de risco durante exames de rotina realizados por profissionais que trabalham com a população infantil e elementos básicos necessários para a realização de uma avaliação minuciosa e criteriosa por uma equipe interdisciplinar. Isso inclui, por exemplo, o uso de instrumentos específicos auxiliares no diagnóstico, elementos importantes para a avaliação médica e psicológica e encaminhamentos para serviços adequados de intervenção e apoio.

When science is not enough – a risk/benefit profile of thiomersal-containing vaccines

Without a preservative, such as thiomersal (known as thimerosal in the US), multi-dose liquid presentations of vaccine are vulnerable to bacteriological contamination that can result in death or serious illness of the recipient. Concerns about levels of mercury exposure from thiomersal-containing vaccines were first raised in the US during 1999 in the context of Hepatitis B vaccine for newborns. Since then, a large body of evidence from animal and epidemiological studies has accumulated on the safety of thiomersal. Ironically, these data have become largely irrelevant in wealthy countries, where mono-dose, thiomersal-free vaccines have been introduced as a precautionary measure in almost all childhood vaccines, in part related to residual public scepticism. In poor countries, multi-dose vials remain important for vaccine delivery. There is a real danger that this controversy may result in the loss to the world of thiomersal as a preservative, simply from popular pressure. In reality, it would be impossible to cease overnight using thiomersal and maintain the supply of vital vaccines. This paper reviews and summarises the data available from published studies on mercury toxicity, and thiomersal in vaccines in particular, that overwhelmingly indicate continued use of thiomersal is safe in those countries where it is most needed.