Is attention-deficit/hyperactivity disorder (ADHD) associated with premature death, and what is the role of psychiatric comorbidity?
This cohort study of Swedish register data of 86 670 individuals with ADHD found that ADHD was associated with elevated risk of premature death, and psychiatric comorbidity played an important role for the all-cause and cause-specific associations in adults. Early-onset psychiatric comorbidity was mainly associated with the risk of natural deaths whereas later-onset psychiatric comorbidity was mainly associated with death due to unnatural causes, including suicide and unintentional injury.
These findings suggest that health care professionals should closely monitor specific psychiatric comorbidities in individuals with ADHD to identify high-risk groups and implement prevention efforts.
A previous register-based study reported elevated all-cause mortality in attention-deficit/hyperactivity disorder (ADHD), but cause-specific risks and the potential associations of psychiatric comorbidities remain unknown.
To investigate the all-cause and cause-specific mortality risks in ADHD and to explore the potential role of psychiatric comorbidities.
Design, Setting, and Participants
This prospective cohort study used Swedish national registers to identify 2 675 615 individuals born in Sweden from January 1, 1983, through December 31, 2009, as the study population, among whom 86 670 individuals (3.2%) received a diagnosis of ADHD during follow-up. Follow-up was completed December 31, 2013, and data were analyzed from October 2018 through March 2019.
Attention-deficit/hyperactivity disorder identified by first clinical diagnosis or first prescription of ADHD medications as recorded in Swedish registers. Clinical diagnosis of psychiatric comorbidity was available in the National Patient Register.
Main Outcomes and Measures
All-cause and cause-specific mortalities and hazard ratios (HRs) using Cox proportional hazards regression models.
In the overall cohort of 2 675 615 individuals, 1 374 790 (51.4%) were male (57 919 with an ADHD diagnosis) and 1 300 825 (48.6%) were female (28 751 with an ADHD diagnosis). Mean (SD) age at study entry was 6.4 (5.6) years. During follow-up, 424 individuals with ADHD and 6231 without ADHD died, resulting in mortality rates of 11.57 and 2.16 per 10 000 person-years, respectively. The association was stronger in adulthood (HR, 4.64; 95% CI, 4.11-5.25) compared with childhood (HR, 1.41; 95% CI, 0.97-2.04) and increased substantially with the number of psychiatric comorbidities with ADHD (HR for individuals with only ADHD, 1.41 [95% CI, 1.01-1.97]; HR for those with ≥4 comorbidities, 25.22 [95% CI, 19.60-32.46]). In adulthood, when adjusting for early-onset psychiatric comorbidity, the association between ADHD and risk of death due to natural causes was attenuated substantially and was no longer statistically significant (HR, 1.32; 95% CI, 0.94-1.85). When adjusting for later-onset psychiatric disorders, the association was attenuated to statistical nonsignificance for death due to suicide (HR, 1.13; 95% CI, 0.88-1.45) but remained statistically significant for death caused by unintentional injury (HR, 2.14; 95% CI, 1.71-2.68) or other external causes (HR, 1.75; 95% CI, 1.23-2.48).
Conclusions and Relevance
Psychiatric comorbidity appears to play an important role in all-cause and cause-specific mortality risks in ADHD. In adulthood, early-onset psychiatric comorbidity contributed primarily to the association with death due to natural causes, whereas later-onset psychiatric comorbidity mainly influenced death due to unnatural causes, including suicide and unintentional injury. These findings suggest that health care professionals should closely monitor specific psychiatric comorbidities in individuals with ADHD to identify high-risk groups for prevention efforts.
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Sun S, Kuja-Halkola R, Faraone SV, et al. Association of Psychiatric Comorbidity With the Risk of Premature Death Among Children and Adults With Attention-Deficit/Hyperactivity Disorder. JAMA Psychiatry. Published online August 07, 2019. doi:10.1001/jamapsychiatry.2019.1944
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