Self-Harm and Premature Death in Young Individuals with Autism – Preliminary Results from a Total Population Study in Sweden
There is increasing concern that people with autism are more likely to die prematurely, particularly by suicide. However, there are little data on the extent of increased mortality and on risk and protective factors. While self-harm behavior in typically developed individuals is a strong predictor of later suicide and death by any cause, its characteristics and impact on mortality in autism is unknown. A detailed understanding of these matters are crucial for prevention of premature mortality in autism.
To examine the association between self- harm and mortality (all cause and by suicide) across the whole spectrum of ASD in a nation-wide contemporary cohort of adolescents and young adults in Sweden. To investigate risk and protective factors in this association, with emphasis on sex, co-morbid conditions, familial and social characteristics.
We conducted a total population study using data from Psychiatry Sweden, a comprehensive record-linkage study. Data on probands, followed-up from 10 to maximum 32 years of age by 2016, their first and second degree relatives, was collected prospectively by record linkage. A total 2 372 500 individuals (51.4 % male), of whom 49 633 were diagnosed with autism (66.3% male) were included in the analyses. The total number of deaths was 8 417.
Exposure was cross-classified as a diagnosis of autism and at least one episode hospital admission for self-harm (ICD-10 codes X60-84 and Y10-34). The outcome was subsequent death, by any cause and by suicide, determined from national Cause of Death Register. Cox hazard proportional regression models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) of death by any cause and by suicide in four groups; neither autism nor self-harm, autism without self-harm, self-harm without autism, and autism with self-harm.
Among individuals diagnosed with autism, 0.2% with no history of self-harm and 3.4% of those with a history of self-harm had died by suicide. The adjusted HRs of suicide in autism without self-harm and in self-harm without autism were 2.4 (95% CI 1.8-3.2) and 20.7 (18.1-23.7), respectively. Among those with both autism and self-harm, the adjusted HR was 42.7 (33.3-58.8). Further results on risk and protective factors in the association between self-harm (including characteristics of the self-harming behavior) and suicide (as well as all-cause mortality) will be presented.
Our findings indicate that individuals with autism who engage in self-harm have a particularly elevated risk of premature death and suicide. This suggests that identification and treatment of this subgroup is important, and that clinical guidelines for suicide risk assessment may have to be revised to recognize this new knowledge.