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Mortality Associated with Autism Spectrum Disorders in a Finnish National Birth Cohort
Previous studies have reported higher risk of mortality among cases with autism spectrum disorders (ASD) compared with the general population. However, there is a lack of study examining the risk of mortality associated with ASD using matched controls and adjusting for covariates.
Objectives:
To examine the association between mortality and ASD after adjusting for covariates.
Methods:
The cohort includes 4705 children born between 1987 and 2005 who were later diagnosed with childhood autism, Asperger’s syndrome or pervasive developmental disorders/ pervasive developmental disorders – not otherwise specified (PDD-NOS). Cases were ascertained from the Finnish Hospital Discharge Register, and each case was matched to four controls by gender, date of birth, place of birth, and residence in Finland. Controls were selected from the Finnish Medical Birth Register. These subjects were followed up for possible mortality until December 31, 2011. Conditional logistic regression models were used to assess the associations between mortality and ASD after controlling for maternal age, maternal and paternal psychiatric history, birth weight and gestational age. In addition, we examined the associations based on the categorization of causes of death (1. natural death, 2. accident, 3. suicide, 4. homicide, 5. unclassified). Because of the small number of deaths in the cohort, adjustment was not done with the causes of death.
Results:
Overall 23 ASD cases (20 males, 3 females) and 50 controls (46 males, 4 females) had died. Prior to adjustment, the risk for mortality in ASD was nearly twofold (OR 1.9, 95 % CI 1.1-3.0, p = 0.016). When adjusted with covariates, the risk slightly decreased (OR 1.7, 95 % CI 0.99-2.8, p = 0.056) and was close to statistical significance. The risk was elevated for natural death (OR 2.7, 95 % CI 0.96-7.6, p = 0.059), accidents (OR 1.9, 95 % CI 0.9-4.1, p = 0.091), and suicides (OR 2.3, 95 % CI 0.9-5.9, p = 0.075) among ASD cases compared with the controls.
Conclusions:
The risk for mortality was increased among subjects diagnosed with ASD. The risk was also elevated for preventable deaths (i.e. accidents and suicides).