The impact of COVID‐19 lockdown on mortality rate in memory clinic patients

Abstract

AbstractBackgroundPeople with (pre‐)dementia were particularly at risk for mortality during the COVID‐19 pandemic due to severe outcome of a COVID‐19 infection and the negative consequences of restrictive measures. Here we study whether patients during the COVID‐19 pandemic had a higher mortality rate compared to historical controls.MethodIn this case‐control study, we included patients from the Amsterdam Dementia Cohort: 1) Pandemic patients (n = 1022) with a baseline visit between January 2017 and December 2018 and 2) Historical controls (n = 930) with a baseline visit between January 2015 and December 2016. Both groups were followed for three years (pandemic patient until 2021 and historical controls until 2019). Absolute standardized mean differences were analyzed in order to determine whether groups were well‐balanced in terms of demographics and cognition at baseline. Cox proportional hazards analyses were performed to compare mortality rate during COVID‐19 pandemic with historical controls. Age, sex, diagnosis, MMSE score, education level, and comorbidity were added as covariates to the model.ResultBoth groups were well‐balanced, as mean age of the pandemic patients was 63±9 years, n = 423 (41%) were female and mean MMSE score was 24.5±5.0. Mean age of the historical controls was 63±8 years, n = 404 (43%) were female and MMSE score was 24.2±5.2. The absolute standardized mean differences were under 0.1 for all selected covariates. Among the pandemic patients, n = 180 (18%) patients died during the previously described follow‐up time. In the historical control group, n = 131 (14%) patients died. Cox proportional hazards models showed that pandemic patients had higher risk for mortality than historical controls (HR [95%‐CI] = 1.27 [1.02‐1.59]). Results remained significant after adjusting for covariates age, sex, diagnosis, MMSE score, education level, and comorbidity (HR [95%‐CI] = 1.37 [1.09‐1.72]).ConclusionMemory clinic patients had increased risk on mortality during times of COVID‐19 lockdown compared to historical controls. This indicates that COVID‐19 lockdown regulations have accelerated disease. Even though the cause of mortality is unknown, it is likely that the excess mortality is not only due to COVID‐19 infections, but also caused by the restrictive measure of the COVID‐19 lockdown restrictions (e.g. social isolation and loss of structure).