Impact of COVID-19 on scheduled lower extremity revascularization for chronic limb-threatening ischemia
Bibliographic record
Abstract
Dear Editor In many jurisdictions internationally, the onset of the COVID-19 pandemic brought about unprecedented stay-at-home orders, restrictions to non-essential in-person health services, and unprecedented emergency department avoidance. These factors contributed to steep but temporary declines in both scheduled and unscheduled invasive procedures1,2. For patients developing chronic limb-threatening ischaemia (CLTI) during the pandemic, delays in scheduled revascularization may have resulted in higher rates of amputation, reduced quality of life, and excess mortality. For a healthcare system, excess amputations would further strain hospital resources, given the high average length of stay among people requiring a leg amputation. In Ontario, Canada, during the first and third COVID-19 waves, hospitals were mandated (on 16 March 2020 and 20 April 2021 respectively) to postpone all scheduled procedures to reserve resources for the rising number of patients with COVID-19. However, given the aforementioned considerations, revascularization for limb-threatening ischaemia remained a relative priority among essential hospital services during periods of restricted care3. Throughout the pandemic, decision analytical modelling has been an essential tool for resource planning to guide health policy under conditions of uncertainty4,5. With a lag in availability of real-world data, modelling offers the ability to explore and quantify the impact of care delays on patients with CLTI. A model-based approach was used to predict the consequences of COVID-19-related delays in lower extremity revascularization (fully endovascular, open or hybrid) for CLTI over the first three waves of the COVID-19 pandemic (18 March 2020 to 16 June 2021), relative to a non-COVID-19 scenario. A microsimulation model with parallel trials simulated the flow of patients with CLTI through the Ontario hospital system for the COVID-19 versus non-COVID-19 scenarios, and projected short- and long-term health outcomes including major (above-ankle) amputation, mortality, and quality-adjusted life-years (QALYs). The model was informed by real-world revascularization volumes, waiting times, and clinical outcome data for the province of Ontario, supplemented with additional data inputs from published literature (Appendix S1 - Supplemental Methods). Important limitations of the data inputs were that revascularization volumes from January to June 2021 were extrapolated from data accrued earlier in the pandemic, and that long-term outcome probabilities, accruable QALYs, and CLTI-related amputation among those not undergoing revascularization were not estimated directly from an Ontario CLTI population (Appendix S1 - Supplemental Methods). In recognition of these limitations, the effect of changes to key model assumptions were explored in a set of sensitivity analyses: increasing the probability of needing urgent surgery (amputation or urgent vascularization) while awaiting scheduled revascularization; increasing the probability of progressing to a non-salvageable limb while awaiting scheduled revascularization; and increasing the severity of ramp-down in scheduled CLTI revascularizations during the third most severe wave. The model suggested that delays in CLTI revascularizations in Ontario during the pandemic resulted in 21 additional major amputations (316 versus 295), and 32 additional deaths (475 versus 443) at 90 days after the index CLTI hospitalization compared with the non-COVID-19 scenario (Table 1). The excess amputation range (21–33) and excess death range (32–47) at 90 days varied by the probability of needing urgent surgery, the probability of progressing to a non-salvageable limb, and the level of ramp-down implemented during the third wave (Table 1). Moreover, compared with a non-COVID-19 situation, patients who sought care for CLTI during COVID-19 in Ontario incurred an excess mean loss of between 0.07 and 0.11 QALYs over their lifetime (837–1110 total QALYs lost) (Table 1). These differences were the downstream effects of: scheduled revascularization for CLTI during COVID-19 being delayed between 6 and 10 additional days on average relative to the non-COVID-19 scenario, and a larger proportion of CLTI revascularizations occurring on an urgent, rather than scheduled, basis (41–52 per cent versus 45–56 per cent scheduled in COVID-19 versus non-COVID-19 scenarios respectively). Summary of results Values in parentheses are numbers of patients unless indicated otherwise; *values are mean with total in parentheses. Results for the scenario analyses are based on an average of 500 runs of the model over the lifetime of simulated patients during the COVID-19 versus non-COVID-19 scenarios. CLTI, chronic limb-threatening ischaemia; QALY, quality-adjusted life-year. Summary of results Values in parentheses are numbers of patients unless indicated otherwise; *values are mean with total in parentheses. Results for the scenario analyses are based on an average of 500 runs of the model over the lifetime of simulated patients during the COVID-19 versus non-COVID-19 scenarios. CLTI, chronic limb-threatening ischaemia; QALY, quality-adjusted life-year. In conclusion, modelling suggests that Ontario has seen a rise in adverse outcomes among the CLTI population requiring revascularization during the course of the pandemic. More generally, the results support the importance of efforts to maintain timely revascularization for patients with CLTI in future situations of hospital care restrictions. CorHealth Ontario provided funding for this work. B.S. is supported by a Canada Research Chair in Economics of Infectious Diseases (CRC-950-232429). C.M. is the recipient of an Ontario Early Researcher Award supporting amputation prevention research in Ontario. Disclosure. The authors declare no conflict of interest. Supplementary material is available at BJS online.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.011 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".