Background:
In Ireland, national surveys have been conducted to measure the impact of COVID-19 pandemic on well-being, however national statistics on mental distress are lacking. This study aimed to investigate the effect of the pandemic by analysing a key indicator of mental distress, antidepressant prescribing.

Methods:
Population-based observational study over 7 years analysing two national datasets of anonymised aggregate dispensing data of WHO ATC classification N06A(antidepressants). The Health Market Research Ireland Ltd.(HMR) dataset is based on national retail pharmacy sales for both private and public patients; and the General Medical Services(GMS) dataset is based on publicly-funded prescriptions (approx.31% of population eligible). Non-GMS figures are derived from the HMR and GMS datasets. Gender and agegroup data only available for GMS dataset. Descriptive statistics, and poisson regression were performed using STATA 15. Incidence Rate Ratios(IRR) with a p-value of <0.05 were considered statistically significant.

Results:
Annual trends found statistically significant changes in the prescribing of antidepressants. Rates increased year on year in both datasets. In the HMR dataset increased prescribing was accelerated by the pandemic; a rate of prescribing in 2020 was 1.07 times higher than 2019 (IRR:1.03), increasing further in 2021 (IRR:1.09). However, in the GMS dataset, the rates decelerated from an IRR of 1.05 in 2019 to 1.04 in 2020 and 1.01 in 2021. By deducting the GMS figures from the HMR figures ‘non-GMS’ prescriptions increased from 1.02 in 2019 to 1.09 in 2020 to 1.16 in 2021.

Conclusion:
This study validates national well-being studies with findings that mental distress increased over time during the pandemic. A novel finding is the different impact on two study populations. In the publicly funded GMS dataset, females accounted for two thirds of prescriptions, and the pandemic impacted the mental health of younger age groups greatest, particularly young females.