Impact of COVID-19 pandemic on elective care backlog trends, recovery efforts, and capacity needs to address backlogs in Scotland (2013-2023): a descriptive analysis and modelling study.

Background: Prioritisation of COVID-19 care led to widespread cancellations of elective care, creating a substantial backlog for healthcare systems worldwide. While the pandemic's impacts on elective hospital waiting lists during the early phase of the pandemic have been described in multiple countries, there is limited research on longer-term impacts and recovery efforts. Methods: We conducted a country-wide analysis of Scotland's healthcare system over an 11-year period (January 1, 2013-December 31, 2023) to assess the pandemic's impact on the elective care backlog, evaluate recovery efforts, and estimate the capacity increase required to clear the backlog. Our analysis involved assessments at national, elective type, regional, and specialty levels. We used descriptive statistics to compare trends and a statistical modelling approach (Vector Autoregressive model with exogenous variables) to estimate capacity increases needed. Findings: Waiting lists gradually increased before the pandemic (2013: n = 285,149; 2019: n = 385,859; 35.3% increase over six years) and then rose rapidly during the pandemic (2023: n = 667,749; 73.1% increase over four years). Capacity for elective care dropped substantially during the initial lockdown period (April-June 2020) and had not fully recovered by the end of 2023. These patterns were broadly consistent across Scotland and similar trends were observed when stratified by elective type, region, and specialty. The number of referrals waiting over a year increased from 3056 on December 31, 2019, to 78,243 (>2400% increase) by December 31, 2023. To eliminate the backlog created during the pandemic, a gradual increase in capacity, accumulating to 20% over three years is required. This corresponds to an annual increase of approximately 6.67%, translating to an additional 32,302 cases per year. Interpretation: Scotland's healthcare system struggled to meet elective care demand pre-pandemic, and the pandemic has worsened an already difficult situation. Pre-pandemic elective care capacity had not been restored by the end of 2023. While substantial additional capacity is necessary, it is crucial to adopt broader system-level strategies to effectively address waiting list backlogs. Funding: University of Edinburgh's Chancellor Fellowship; Health Data Research UK.