Mortality trends from 2010-2023 and excess mortalities in Perak during the COVID-19 pandemic

COVID-19, caused by SARS-CoV-2 virus, is a respiratory infection that led to the 2020 pandemic. During the pandemic, mortality directly related to COVID-19 infection were classified as COVID-19 death based on case definition. However, excess mortality would be a more comprehensive method to look at the true impact of the pandemic rather than focusing only on COVID-19 deaths alone. The objective of this study was to determine the excess mortalities and top 5 causes of mortality that occurred during and after the COVID-19 pandemic in Perak.

Total and age-specific mortality data tabulated by the Department of Statistics Malaysia (DOSM) for the years 2010-2023 for the state of Perak was obtained. Data for the years 2010-2019 was re-grouped according to clustered age groups. This was used to generate the linear prediction line for mortality in 2020-2023 using Microsoft Excel 2010. Excess mortalities were calculated for 2020-2023 by subtracting the actual deaths from the predicted deaths. The top 5 common causes of mortality and COVID-19 deaths were also re-tabulated for the years 2020-2023 for the clustered age groups. "Positive Excess Mortality" (PEM) meant that the number of actual deaths were higher than predicted and "Negative Excess Mortality" (NEM) meant that the actual deaths were lower than the predicted number. Significant PEM meant that the value of the actual mortality was above the upper limit of the 95% confidence interval of the predicted mortality.

All clustered age groups showed NEM for the year 2020. For the years 2021-2022, there was a PEM for all clustered age groups except those in the group "19 and below". The highest excess mortality was in the "65 and above" group with 343.44 and 685.56 per 100,000 agespecific population for 2021 and 2022 respectively. The mortality rate returned to the predicted value in 2023. In 2021 and 2022, there was a PEM for the "20-39" and "40-64" clustered age groups, however they were lower compared to the "65 and above" groups. Significant PEM was seen for all deaths in the "65 and above" in 2021 (237 per 100,000) and in 2022, 596 per 100,000. There was also a significant PEM after the removal of COVID-19 deaths in 2022 for the "65 and above" age groups- 366 per 100,000. Significant PEM was also seen in the "20-39" age groups and "40-64" age groups in 2021- 14 per 100,000 and 36 per 100,000 respectively. The other values that passed the 95%CI were deemed to be negligible. There were a few changes in the top 5 ranking for causes of death in Perak, the only obvious inclusion was deaths due to COVID-19 infections in 2021 in all groups except the "19 and below".

There was a PEM in all groups except "19 and below" after the year 2020, with the highest in the "65 and above" group. COVID-19 deaths were included in the top 5 causes of death and contributed only partly to the excess mortality across all groups except "19 and below".