Patterns of mortality among adults with intellectual and developmental disabilities in the Canadian province of Manitoba

Objectives The goals of this study were to examine and compare (a) the annual adult mortality rates and (b) the most commonly reported underlying causes of death between a cohort of Manitobans with intellectual and developmental disabilities (IDD) and a matched comparison group without IDD. Methods Using linked health and nonhealth administrative data, a cohort of Manitoba adults with IDD, aged 25-99 years in 2012, was identified. Each person in the study cohort was matched with three persons without IDD based on age, sex, region of residence, and morbidity level. The two groups were followed for three years (2013-2015). Crude annual adult mortality rates and avoidable premature mortality rates were calculated. The leading causes of death over the 3-year study period were tabulated by ICD-10 chapter. Coding of the underlying causes of death was reviewed. Results The crude annual mortality rates for Manitoba adults with IDD were 1.8-2.4 times higher than those for the matched comparison group and remained stable over time. Disparities in mortality rates for the IDD cohort relative to the matched comparison group decreased with increasing age. No significant sex differences were found. The leading causes of death among the IDD cohort were diseases of the circulatory system, cancer, and diseases of the respiratory system. Avoidable premature deaths were 2.3-3.3 times more prevalent among Manitoba adults with IDD compared to the matched comparison group. An IDD diagnostic code was reported as cause of death in 2.11% of cases. Conclusions The excess mortality among adults with IDD should be monitored in Manitoba and all other jurisdictions and attention paid to the causes of death and their coding.