A cohort study of patients hospitalised with SARS-CoV-2 infection in Ontario: patient characteristics and outcomes by wave.

INTRODUCTION: Each wave of the COVID-19 pandemic exhibited a unique combination of epidemiological, social and structural characteristics. We explore similarities and differences in wave-over-wave characteristics of patients hospitalised with COVID-19. METHODS: This was a population-based study in Ontario province, Canada. Patients hospitalised with SARS-CoV-2 between 26 February 2020 and 31 March 2022 were included. An admission was considered related to SARS-CoV-2 infection if the provincial inpatient or outpatient hospital databases contained the ICD-10 diagnostic codes U071/U072 or the Ontario Laboratories Information System indicated a positive SARS-CoV-2 test result (PCR or rapid antigen testing) during the admission or up to two weeks prior. The primary outcome was 90-day mortality (modified Poisson regression). Secondary outcomes were use of critical care during the admission (logistic regression) and total length-of-stay (linear regression with heteroskedastic-consistent standard-error estimators). All models were adjusted for demographic characteristics, neighbourhood socioeconomic factors and indicators of illness severity. RESULTS: There were 73,201 SARS-CoV-2-related admissions: 6127 (8%) during wave 1 (wild-type), 14,371 (20%) during wave 2 (wild-type), 16,653 (23%) during wave 3 (Alpha), 5678 (8%) during wave 4 (Delta) and 30,372 (42%) during wave 5 (Omicron). SARS-CoV-2 was the most responsible diagnosis for 70% of admissions during waves 1-2 and 42% in wave 5. The proportion of admitted patients who were long-term care residents was 18% (n = 1111) during wave 1, decreasing to 10% (n = 1468) in wave 2 and <5% in subsequent waves. During waves 1-3, 46% of all admitted patients resided in a neighbourhood assigned to the highest ethnic diversity quintile, which declined to 27% during waves 4-5. Compared to wave 1, 90-day mortality was similar during wave 2 (adjusted risk ratio [aRR]: 1.00 [95% CI: 0.95-1.04]), but lower during wave 3 (aRR: 0.89 [0.85-0.94]), wave 4 (aRR: 0.85 [0.79-0.91]) and wave 5 (aRR: 0.83 [0.80-0.88]). Improvements in survival over waves were observed among elderly patients (p-interaction <0.0001). Critical care admission was significantly less likely during wave 5 than previous waves (adjusted odds ratio: 0.50 [0.47-0.54]). The length of stay was a median of 8.5 (3.6-23.8) days during wave 1 and 5.3 (2.2-12.6) during wave 5. After adjustment, the mean length of stay was on average -10.4 (-11.1 to -9.8) days, i.e. shorter, in wave 5 vs wave 1. CONCLUSION: Throughout the pandemic, sociodemographic characteristics of patients hospitalised with SARS-CoV-2 changed over time, particularly in terms of ethnic diversity, but still disproportionately affected patients from more marginalised regions. Improved survival and reduced use of critical care during the Omicron wave are reassuring.

The effect of the COVID-19 pandemic on hospital admissions and outpatient visits in Ontario, Canada.

INTRODUCTION: The wave-over-wave effect of the COVID-19 pandemic on hospital visits for non-COVID-19-related diagnoses in Ontario, Canada remains unknown. METHODS: We compared the rates of acute care hospitalizations (Discharge Abstract Database), emergency department (ED) visits, and day surgery visits (National Ambulatory Care Reporting System) during the first five "waves" of Ontario's COVID-19 pandemic with prepandemic rates (since January 1, 2017) across a spectrum of diagnostic classifications. RESULTS: Patients admitted in the COVID-19 era were less likely to reside in long-term-care facilities (OR 0.68 [0.67-0.69]), more likely to reside in supportive housing (OR 1.66 [1.63-1.68]), arrive by ambulance (OR 1.20 [1.20-1.21]) or be admitted urgently (OR 1.10 [1.09-1.11]). Since the start of the COVID-19 pandemic (February 26, 2020), there were an estimated 124,987 fewer emergency admissions than expected based on prepandemic seasonal trends, representing reductions from baseline of 14% during Wave 1, 10.1% in Wave 2, 4.6% in Wave 3, 2.4% in Wave 4, and 10% in Wave 5. There were 27,616 fewer medical admissions to acute care, 82,193 fewer surgical admissions, 2,018,816 fewer ED visits, and 667,919 fewer day-surgery visits than expected. Volumes declined below expected rates for most diagnosis groups, with emergency admissions and ED visits associated with respiratory disorders exhibiting the greatest reduction; mental health and addictions was a notable exception, where admissions to acute care following Wave 2 increased above prepandemic levels. CONCLUSIONS: Hospital visits across all diagnostic categories and visit types were reduced at the onset of the COVID-19 pandemic in Ontario, followed by varying degrees of recovery.

Mechanical thrombectomy in patients with acute ischemic stroke: a cost-utility analysis.

BACKGROUND: The beneficial effects of endovascular treatment with new-generation mechanical thrombectomy devices compared with intravenous thrombolysis alone to treat acute large-artery ischemic stroke have been shown in randomized controlled trials (RCTs). This study aimed to estimate the cost utility of mechanical thrombectomy compared with the established standard of care. METHODS: We developed a Markov decision process analytic model to assess the cost-effectiveness of treatment with mechanical thrombectomy plus intravenous thrombolysis versus treatment with intravenous thrombolysis alone from the public payer perspective in Canada. We conducted comprehensive literature searches to populate model inputs. We estimated the efficacy of mechanical thrombectomy plus intravenous thrombolysis from a meta-analysis of 5 RCTs, and we used data from the Oxford Vascular Study to model long-term clinical outcomes. We calculated incremental cost-effectiveness ratios (ICER) using a 5-year time horizon. RESULTS: The base case analysis showed the cost and effectiveness of treatment with mechanical thrombectomy plus intravenous thrombolysis to be $126 939 and 1.484 quality-adjusted life-years (QALYs), respectively, and the cost and effectiveness of treatment with intravenous thrombolysis alone to be $124 419 and 1.273 QALYs, respectively. The mechanical thrombectomy plus intravenous thrombolysis strategy was associated with an ICER of $11 990 per QALY gained. Probabilistic sensitivity analysis showed that the probability of treatment with mechanical thrombectomy plus intravenous thrombolysis being cost-effective was 57.5%, 89.7% and 99.6% at thresholds of $20 000, $50 000 and $100 000 per QALY gained, respectively. The main factors influencing the ICER were time horizon, extra cost of mechanical thrombectomy treatment and age of the patient. INTERPRETATION: Mechanical thrombectomy as an adjunct therapy to intravenous thrombolysis is cost-effective compared with treatment with intravenous thrombolysis alone for patients with acute large-artery ischemic stroke.

Mechanical Thrombectomy in Acute Ischemic Stroke: A Systematic Review.

Although intravenous thrombolysis increases the probability of a good functional outcome in carefully selected patients with acute ischemic stroke, a substantial proportion of patients who receive thrombolysis do not have a good outcome. Several recent trials of mechanical thrombectomy appear to indicate that this treatment may be superior to thrombolysis. We therefore conducted a systematic review and meta-analysis to evaluate the clinical effectiveness and safety of new-generation mechanical thrombectomy devices with intravenous thrombolysis (if eligible) compared with intravenous thrombolysis (if eligible) in patients with acute ischemic stroke caused by a proximal intracranial occlusion. We systematically searched seven databases for randomized controlled trials published between January 2005 and March 2015 comparing stent retrievers or thromboaspiration devices with best medical therapy (with or without intravenous thrombolysis) in adults with acute ischemic stroke. We assessed risk of bias and overall quality of the included trials. We combined the data using a fixed or random effects meta-analysis, where appropriate. We identified 1579 studies; of these, we evaluated 122 full-text papers and included five randomized control trials (n=1287). Compared with patients treated medically, patients who received mechanical thrombectomy were more likely to be functionally independent as measured by a modified Rankin score of 0-2 (odds ratio, 2.39; 95% confidence interval, 1.88-3.04; I2=0%). This finding was robust to subgroup analysis. Mortality and symptomatic intracerebral hemorrhage were not significantly different between the two groups. Mechanical thrombectomy significantly improves functional independence in appropriately selected patients with acute ischemic stroke.