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Patterns of mortality among adults with intellectual and developmental disabilities in Ontario

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To determine recent mortality rates among Ontarian adults with intellectual and developmental disabilities (IDDs) and investigate changes over time in contrast to the general population. To determine the most commonly reported underlying causes of death and explore related coding practices.


Using linked health administrative data, four cohorts of adults with IDD aged 25–99 living in Ontario were followed for 1 year (one cohort for each year between 2011 and 2014). Deaths (2011 to 2014) and causes of death (2011 to 2013) were identified, and age-standardized mortality rates were calculated annually. For 2013, overall and sex-specific standardized mortality ratios (SMRs) were calculated. Mortality ratios were also examined across 5-year age groups. Commonly reported causes of death were tabulated by ICD-10 chapter, differences by sex examined, and cause-specific SMRs calculated. All deaths with IDD diagnostic codes reported as underlying cause of death were identified.


Mortality rates among individuals with IDD have been decreasing over time; in 2014, the mortality rate was 22.6 deaths per 1000 person-years. Disparities in mortality rates relative to the general population decreased with increasing age. Men with IDD had higher mortality rates than women with IDD. The most common causes of death among individuals with IDD were cardiovascular disease, neoplasms, and diseases of the respiratory system. An IDD diagnostic code was reported as cause of death in 3.8% of cases.


The ongoing excess mortality among Ontarians with IDD should be closely monitored by policy makers and service providers. Attention to cause of death reporting should be considered so that cause of death can be thoroughly examined.



Déterminer le taux de mortalité récent chez les adultes ontariens ayant une déficience intellectuelle et développementale (DID) et explorer les changements au fil du temps des disparités avec la population générale. Déterminer les causes déclarées les plus communes qui expliquent le décès et explorer les pratiques de codage connexes.


Au moyen des données administratives sur la santé, quatre cohortes d’adultes ayant une DID âgés de 25 à 99 ans vivant en Ontario ont été suivies pendant un an (une cohorte par année entre 2011 et 2014). Les décès (2011 à 2014) et les causes des décès (2011 à 2013) ont été cernés, et le taux de mortalité normalisé selon l’âge calculé chaque année. Pour 2013, on a calculé le ratio standardisé de mortalité (RSM) selon le genre. On a également examiné le ratio de mortalité par groupe d’âge de cinq ans. Les causes de décès déclarées le plus souvent ont été totalisées selon le chapitre du CIM-10, les différences selon le genre examinées et les causes propres au RSM calculées. Tous les décès portant un code de diagnostic DID pour désigner une cause sous-jacente ont été identifiés.


Le taux de mortalité chez les personnes ayant une DID a baissé avec le temps; il était de 22,6 par 1000 années-personnes en 2014. L’écart du taux de mortalité par rapport à la population générale a baissé avec l’âge. Les hommes ayant une DID avaient un taux de mortalité supérieur à celui des femmes ayant une DID. Les causes les plus fréquentes de décès chez les personnes ayant une DID étaient les maladies vasculaires, les tumeurs et les maladies du système respiratoire. Un code de diagnostic de DID a été déclaré comme cause du décès dans 3,8% des cas.


Les décideurs et fournisseurs de service doivent surveiller de près la surmortalité actuelle chez les Ontariens ayant une DID. Il faut porter plus d’attention à la déclaration de la cause du décès pour être en mesure de l’examiner en profondeur.

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This study relied on data held at the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). The opinions, results, and conclusions reported in this paper are those of the authors and are independent from the funding sources. No endorsement by ICES or the Ontario MOHLTC is intended or should be inferred. Parts of this material are based on data and/or information compiled and provided by the Canadian Institute for Health Information (CIHI). However, the analyses, conclusions, opinions, and statements expressed in the material are those of the author (s) and not necessarily those of CIHI. The authors wish to acknowledge the contributions of Marlo Whitehead, Senior Programmer and Biostatistician at ICES @ Queen’s Health Sciences Research Facility, for preparation of the dataset.

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Correspondence to Hélène Ouellette-Kuntz.

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This study was reviewed for ethical compliance by the institutional review board at Sunnybrook Health Sciences Centre, Toronto, Canada and the Queen’s University Health Sciences and Affiliated Teaching Hospitals Research Ethics Board, Kingston, Canada.

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Stankiewicz, E., Ouellette-Kuntz, H., McIsaac, M. et al. Patterns of mortality among adults with intellectual and developmental disabilities in Ontario. Can J Public Health 109, 866–872 (2018).

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