Trends in medication use after the onset of the COVID-19 pandemic in the Republic of Ireland: an interrupted time series study

Abstract

Abstract Introduction The COVID-19 pandemic had a substantial impact on a range of health services, particularly in primary care. Research from Ireland suggests while community pharmacies remained open, restrictions for in-person healthcare appointments impacted patients.[1] Although there is evidence that the onset of the pandemic affected medicines utilisation internationally,[2] it is unclear how prescribing in Ireland changed following March 2020. Aim To evaluate how dispensing of medications in primary care in Ireland changed following the onset of the COVID-19 pandemic compared to expected trends. Methods This was an interrupted time series study, and the protocol was pre-registered (doi.org/10.17605/OSF.IO/WNQHR). It used publicly available data from the Health Service Executive Primary Care Reimbursement Services for each month between January 2016 and July 2022. Data covered dispensing on the General Medical Services (i.e. medical card) scheme for all medication therapeutic subgroups and commonly dispensed medications (based on the top 100 individual medications per month). Pre-pandemic data (January 2016-November 2019) was used to forecast expected trends from December 2019 onwards for each subgroup and medication with 99% prediction intervals. The Holt-Winters method was used, which decomposes time series data into seasonal, trend, and irregular components. Three months of observed data unaffected by the pandemic (December 2019-February 2020, validation period) were compared to the forecast to validate accuracy of predictions. Observed data were compared to forecasts in March 2020 (as the first month of pandemic restrictions in Ireland) and over the remainder of the study period from April 2020-July 2022. Statistical significance was defined as observed data outside the 99% prediction interval (p<0.01). Results The overall number of dispensings was 7.6% (99%CI 2.5% to 13.2%) higher than forecast in March 2020. Many (31/77) therapeutic subgroups had dispensing significantly different from forecast in March 2020. Drugs for obstructive airway disease had the largest difference, with dispensing 26.2% (99%CI 19.5%-33.6%) higher than forecasted. Other subgroups with dispensing significantly higher than forecasted included minerals, analgesics, thyroid therapy, serum lipid-reducing agents and diuretics. Dispensing was significantly lower than forecasted for other gynaecologicals (17.7% lower, 99%CI 6.3%-26.6%) and dressings (11.6%, 99%CI 9.4%-41.6%). Similarly, many individual medications had significantly higher dispensing in March 2020. Notably, dispensing of amoxicillin (with/without clavulanic acid) and oral prednisolone were lower than forecasted in the months following the onset of the pandemic, particularly during winter 2020/2021. Conclusion There was a peak in dispensing for many long-term medications in March 2020 suggesting patients obtained additional supplies of their regular medicines as pandemic restrictions were introduced. Exceptions were dispensing of two therapeutic subgroups (dressings/intrauterine devices) linked to in-person healthcare consultations, illustrating the disruption to service delivery. Lower than expected dispensing of antimicrobials and reduced seasonal peaks may be partly due to reduced infection transmission generally. Although we were limited by lacking data on the number of people dispensed each medication, this is the first study to examine changes in medication use during the COVID-19 pandemic in Ireland, considering all therapeutic areas. This study provides evidence to inform planning for medication demand and supply for future major health events.