Adults who underwent cardiac surgery at two major Canadian centres during the COVID-19 pandemic spent a similar number of days alive and out of hospital in the first 90 days after surgery as patients operated on before the pandemic, according to a retrospective cohort study published in BMC Anesthesiology. The study, which included 5,630 patients treated at Toronto General Hospital and the University of Ottawa Heart Institute between March 15, 2018 and March 15, 2022, found no sustained, statistically significant change in the monthly trend of this patient-centred measure after the first Ontario directive to postpone elective surgery on March 15, 2020.
The researchers used a metric known as Days Alive and Out of Hospital at 90 days, or DAOH-90, which captures both survival and time spent outside hospital in the three months following an operation. Because the measure combines mortality and length of stay into a single number, it is often used to reflect outcomes that matter to patients rather than isolated clinical endpoints. The cohort was divided into three procedure groups: 2,549 patients (45 percent) underwent coronary artery bypass grafting, 1,657 (29 percent) had single valve surgery, and 1,424 (25 percent) underwent complex procedures, defined as bypass grafting combined with at least one valve repair or replacement, or multivalve surgery without bypass grafting.
To assess whether the pandemic disrupted outcomes, the team applied interrupted time-series models to monthly mean DAOH-90 values for each procedure type, with March 15, 2020 specified as the interruption point. For coronary artery bypass grafting, the estimated change in monthly mean DAOH-90 at the interruption was −0.93 days (standard error 1.07; 95 percent confidence interval −3.03 to 1.17; p = 0.39), which was not statistically significant. For complex surgery, the estimated change was +0.79 days (standard error 2.35; 95 percent confidence interval −3.82 to 5.40; p = 0.74), also not statistically significant.
One exception appeared in the single valve surgery group, where the estimated change at the interruption was −2.82 days (standard error 1.21; 95 percent confidence interval −5.19 to −0.45; p = 0.03), suggesting a small drop in DAOH-90 coinciding with the pandemic onset. However, in a sensitivity analysis this difference was attenuated and no longer statistically significant, at −2.86 days (95 percent confidence interval −5.93 to 0.21; p = 0.07). The slope changes after the interruption were +0.14, −0.04, and +0.13 days per month for the bypass grafting, single valve, and complex surgery groups respectively, and none of these reached statistical significance, with all p values at or above 0.12. Taken together, the authors concluded that the specified models did not demonstrate a sustained, statistically significant change in monthly mean DAOH-90 after March 15, 2020.
Beyond the pandemic comparison, an exploratory analysis using patient-level zero-inflated beta-binomial models examined whether sex, rurality, and neighbourhood income were associated with the outcome. Female patients had lower mean DAOH-90 than males for all procedure types both before and after pandemic onset, with the difference most pronounced in the valve surgery cohort. Patients living in the two lowest neighbourhood income quintiles also had lower mean DAOH-90 both before and during the pandemic. By contrast, mean DAOH-90 was not associated with rurality in this cohort.
The study’s design carries important limitations. As a retrospective analysis of patients from two Canadian centres, its findings may not generalise to other health systems, and the exploratory patient-level analyses were not designed to establish causal effects. The interrupted time-series models relied on a single specified interruption date and monthly aggregate data, and the authors note that the pandemic’s impact on patient-centred outcomes had remained unclear before this analysis. The article was published as an open-access paper on October 23, 2026, and is being shared early to provide faster access to peer-reviewed, accepted research, with the final version of record to follow.
Subject of Research: Days alive and out of hospital at 90 days among cardiac surgery patients before and during the COVID-19 pandemic
Article Title: Days alive and out of hospital in patients undergoing cardiac surgery during the COVID-19 pandemic
Article References: Bartoszko, J., Sun, L. Y., Petrcich, W., Miles, S., Peer, M., Ouzounian, M., Rao, V., Tsang, W., Quereshy, F., Garijo, J. M., Mashari, A., & van Klei, W. A. (2026). Days alive and out of hospital in patients undergoing cardiac surgery during the COVID-19 pandemic. BMC Anesthesiology. https://doi.org/10.1186/s12871-026-04378-7
Image Credits: AI Generated
DOI: 10.1186/s12871-026-04378-7
Keywords: cardiac surgery, COVID-19 pandemic, DAOH-90, retrospective cohort study, interrupted time series, coronary artery bypass grafting, valve surgery, health equity, hospital length of stay, BMC Anesthesiology, patient-centred outcomes, Ontario
News Source: Ophelia Keating. (October 29, 2026). Cardiac surgery outcomes stayed largely stable through the COVID-19 pandemic, study finds. Scienmag.
