COVID-19 infection and outcomes in a population-based cohort of 17,173 adults with intellectual disabilities compared with the general population
Authors: Henderson Angela , Fleming Michael , Cooper Sally-Ann , Pell Jill , Melville Craig , MacKay Daniel , Hatton Chris , Kinnear Deborah 
Published: February 2021

Objectives

To compare COVID-19 infection, severe infection, mortality, case-fatality, and excess deaths, among adults with intellectual disabilities and those without.

Design

Record-linkage of all adults recorded with intellectual disabilities in Scotland’s Census, 2011, and a 5% sample of other adults, to COVID-19 test results (Electronic Communication of Surveillance in Scotland), hospitalisations (Scottish Morbidity Record 01), and deaths (National Records of Scotland).

Setting

General population; 24th January 2020 - 15th August 2020

Participants

Successful linkage of 94.8% provided data on 17,173 adults with, and 195,859 without, intellectual disabilities.

Outcomes

Crude rates of COVID-19 infection, severe infection (hospitalisation/death), mortality, and case fatality; age-, sex- and deprivation-standardised severe infection and mortality ratios; annual all-cause mortality for 2020 and 2015-2019.

Results

Adults with intellectual disabilities had higher rates of COVID-19 infection (957/100,000 versus 513/100,000); severe infection (549/100,000 versus 237/100,000); mortality (259/100,000 versus 114/100,000); and case-fatality (30% versus 24%). Poorer COVID-19 outcomes remained after standardising for age, sex and deprivation: standardised severe infection ratio 2.59 (95% CI 1.80, 3.39) and mortality ratio 3.20 (95% CI 2.16, 4.25). These were higher among 55-64 year olds: 7.12 (95% CI 3.73, 10.50) and 16.16 (95% CI7.69, 24.63) respectively. Among adults with intellectual disabilities, all-cause mortality was only slightly higher in 2020 than the previous five years: standardised mortality ratios 2.49 (95% CI 2.17, 2.81) and 2.38 (95% CI 2.26, 2.49) respectively.

Conclusions

Adults with intellectual disabilities were more likely to be infected with COVID-19, and had worse outcomes once infected, particularly those under 65 years. Non-pharmaceutical interventions directed at formal and informal carers are essential to reduce transmission and all adults with intellectual disabilities should be immediately prioritised for vaccination regardless of age.

Summary box

What is already known on this topic

COVID-19 mortality is higher within multi-occupancy residences.

Adults with intellectual disabilities may be at higher risk of COVID-19 mortality than other adults, but there are gaps in the evidence.

COVID-19 case-fatality may be no different, or as much as 2.75 times higher in adults with intellectual disabilities compared with other adults.

What this study adds

Compared with general population adults, adults with intellectual disabilities were almost twice as likely to become infected with COVID-19, 2.3 times as likely to have severe infection, 2.3 times as likely to have COVID-19 mortality, and had 25% higher COVID-19 case-fatality.

After standardising for age, sex and deprivation, people with intellectual disabilities were 3.2 times more at risk of covid-19 mortality and 2.6 times more at risk of severe infection relative to those with no intellectual disabilities

Compared with general population adults, adults with intellectual disabilities had poorer outcomes among non-elderly age-groups particularly those aged 55-65 years, men, and those living in less-deprived neighbourhoods.

Non-pharmaceutical initiatives are important for carers and care-provider organisations, and adults with intellectual disabilities should be prioritised in the national rollouts of COVID-19 vaccination programmes, regardless of age, sex, or neighbourhood deprivation.