MEDIATION ANALYSIS TO INFORM POLICY ON CORONARY REVASCULARIZATION BY EXPECTED TIME TO TREATMENT: ANALYTICAL FRAMEWORK

Objectives Clinical guidelines favor coronary artery bypass grafting (CABG) over percutaneous coronary intervention (PCI) for patients with stable complex coronary disease. Yet the benefit of CABG as established in trials may not be generalizable to populations in which treatment method determines time to treatment, typically being longer for CABG. For cases in which the cardiac anatomy is suitable for either treatment, it is unclear whether it is appropriate to recommend CABG, which is likely to be delayed, if PCI can be performed sooner. This paper outlines an analytical framework for a policy analysis of the timing of coronary revascularization. Methods We constructed a thought experiment to examine whether time to treatment will influence the advantage of CABG. We substantiated the use of mediation analysis to estimate the extent to which differences in outcomes between CABG and PCI would change if times to CABG were the same as times to PCI. Results We designed a study that uses data from a population-based patient registry to obtain effect measures of mediation analysis: the total effect, the natural indirect effect, and the natural direct effect. The partitioning of the total effect will allow us to estimate the proportional reduction in the risk of an outcome if the time to CABG was similar to that of PCI. Interpretation Treatment recommendation, resource allocation and scheduling benchmarks will be guided by understanding the extent to which the time to treatment mediates the relation between revascularization method and outcome.

Optimal Transport Scenario With Rotary Air Transport for Access to Endovascular Therapy Considering Patient Outcomes and Cost: A Modeling Study

Background and Purpose: For an ischemic stroke patient whose onset occurs outside of the catchment area of a hospital that is capable of Endovascular Treatment (EVT) and whose stroke is suspected to be caused by a large vessel occlusion (LVO), a transportation dilemma exists. Bypassing the nearest stroke hospital will delay Alteplase but expedite EVT. Not bypassing allows for confirmation of an LVO diagnosis before transfer to an EVT-enabled facility, but ultimately delays EVT. Air transport can reduce a patient's overall time to treatment however, it is costly. We expanded on an existing model to predict where Drip-and-Ship vs. Mothership provides better outcomes by including rotary air transport, and we also included prediction of where either the transport method was most cost effective.Methods: An existing model predicts the outcome of patients who screen positive for an LVO in the field based on how they were transported, Drip-and-Ship (alteplase-only facility first, then EVT-enabled facility) or Mothership (direct to EVT-enabled facility). In our model, the addition of rotary wing transportation was conditionally applied to inter-facility transfer scenarios where it provided a time advantage. Both patient outcome and transport cost functions were developed for Mothership and Drip-and-Ship strategies including transfers via either ground or air depending on the conditional probabilities. Experiments to model real world scenarios are presented by varying the driving time between the alteplase-only and EVT-enabled facility, time to treatment efficiencies at the alteplase-only facility, and EVT eligibility for LVO patients. Patient outcome and transport costs were evaluated for Mothership and Drip-and-Ship strategies.Results: The results are presented in temporospatial diagrams that are color coded to indicate which strategy optimizes the objectives. In most regions, there was overall agreement between the optimal solution when considering patient outcomes or transport costs. Small regions exist where outcome and cost are divergent; however, the difference between the divergence in Mothership and Drip-and-Ship in these regions is marginal.Conclusions: The optimal transport method can be optimized for both patient outcomes and transport costs.

Real-World Management and Clinical Outcomes of Stroke Survivors With Atrial Fibrillation: A Population-Based Cohort in Spain

Objective: Despite the continuous update of clinical guidelines, little is known about the real-world management of patients with atrial fibrillation (AF) who survived a stroke. We aimed to assess patterns of therapeutic management of stroke survivors with AF and clinical outcomes using data from routine practice in a large population-based cohort.Methods: A population-based retrospective cohort study of all patients with AF who survived a stroke, from January 2010 to December 2017 in the Valencia region, Spain (n = 10,986), was carried out. Treatment strategies and mean time to treatment initiation are described. Temporal trends are shown by the management pattern during the study period. Factors associated with each pattern (including no treatment) vs. oral anticoagulant (OAC) treatment were identified using logistic multivariate regression models. Incidence rates of clinical outcomes (mortality, stroke/TIA, GI bleeding, and ACS) were also estimated by the management pattern.Results: Among stroke survivors with AF, 6% were non-treated, 23% were prescribed antiplatelets (APT), 54% were prescribed OAC, and 17% received OAC + APT at discharge. Time to treatment was 8.0 days (CI 7.6–8.4) for APT, 9.86 (CI 9.52–10.19) for OAC, and 16.47 (CI 15.86–17.09) for OAC + APT. Regarding temporal trends, management with OAC increased by 20%, with a decrease of 50% for APT during the study period. No treatment and OAC + APT remained relatively stable. The strongest predictor of no treatment and APT treatment was having the same management strategy pre-stroke. Those treated with APT had the highest rates of GI bleeding and recurrent stroke/TIA, and untreated patients showed the highest rates of mortality.Conclusion: In this large population-based cohort using real-world data, nearly 30% of AF patients who suffered a stroke were untreated or treated with APT, which overall is not recommended. Treatment was started within 2 weeks as recommended, except for OAC + APT, which was started later. The strong association of APT treatment or non-treatment with the same treatment strategy before stroke occurrence suggests a strong therapeutic inertia and opposes recommendations. Patients under these two strategies had the highest rates of adverse outcomes. An inadequate prescription poses a great risk on patients with AF and stroke; thus monitoring their management is necessary and should be setting-specific.

P-OGC80 The effect of COVID -19 on new diagnosis oesophagogastric cancer patients in the UK: A single-centre experience

Background Covid-19 has had a devastating global impact and resulted in over 4.4 million directly attributed deaths. The UK entered lockdown in March 2020, redistributing its medical workforce and resources. Early estimations suggested at least 4700 extra cancer deaths at 5 years if there was a 3-month delay to surgery. Delays to diagnosis and treatment for osophagogastric (OG) cancers can be particularly detrimental to survival. The aim of this study is to assess the impact of Covid-19 on new cancer referrals to a centralised UK OG cancer centre, including presentation, decision making and treatment. Methods Patients with OG cancer referred to a tertiary, high-volume centre between March 2019 and March 2021 were reviewed. Patients were stratified into Pre-covid (March 2019-March 2020) and Covid (March 2020-2021) cohorts. Number of new referrals, clinical stage, treatment decision, and time to treatment were compared for gastric adenocarcinoma (GA), oesophagogastric-junction adenocarcinoma (OGJA), oesophageal adenocarcinoma (OA) and oesophageal SCC (OSCC). Results There was an 11% reduction in new cancer referrals (485 vs 431). GA, OGJA and OA did not have significant change in treatment intent, although there was a significant increase in the decision for definitive non-surgical treatment of OA (P = 0.046). GA and OA patients had a small, but significant increase in mean clinical stage at presentation (P < 0.05). There was no increase in time to treatment for GA, OGJA and OA. A significantly higher proportion of OSCC patients were given curative intent treatment in the Covid-19 cohort (P = 0.0006) however, this was accompanied with an increased time to treatment commencement (35.8 days vs 27.9 days P = 0.0198). Conclusions This high-volume centre has seen a reduction in new cancer referrals since the first UK lockdown. This was associated with a small, but significant, increase in clinical stage of GA and OA at presentation. This may represent an early indication of excess oesophagogastric cancer deaths due to the impact of Covid-19. This data also confirms initial results showing that oncological decisions were not compromised, although Covid-19 remains a dynamic challenge.