Does stroke-associated pneumonia play an important role on risk of in-hospital mortality associated with severe stroke? A four-way decomposition analysis of a national cohort of stroke patients.

BACKGROUND: Severe strokes and stroke-associated pneumonia (SAP) have long been associated with poorer patient health outcomes, for example, in-hospital mortality. However, it is unclear what role SAP plays in the risk of in-hospital mortality associated with a severe stroke at admission. METHODS: Using the Sentinel Stroke National Audit Program data on stroke admissions (2013-2018) in England and Wales, we modeled the "total" effect for severe stroke on risk of in-hospital mortality. Through four-way decomposition methodology, we broke down the "total" observed risk into four components. The direct "severity on outcome only" effect, the pure indirect effect of severity mediated via SAP only, the interaction between severity and SAP when mediation is not present, and when mediation via SAP is present. RESULTS: Of 339,139 stroke patients included, 9.4% had SAP and 15.6% died in hospital. Of SAP patients, 45% died versus 12% of non-SAP patients. The risk ratio for in-hospital mortality associated with severe versus mild/moderate stroke (i.e. total effect) was 4.72 (95% confidence interval: 4.60-4.85). Of this, 43%-increased risk was due to additive SAP interaction, this increased to 50% for "very severe" stroke. The remaining excess relative risk was due to the direct severity on outcome effect only, that is, there was no evidence here for a mediation effect via SAP. CONCLUSION: SAP was associated with a higher mortality in severe stroke patients. Prioritizing SAP prevention in severe stroke patients may improve in-hospital survival. Our results suggest that in severe stroke patients avoiding SAP might result in an up to 43% reduction in mortality.

Do Stroke Care Processes Modify Clinical Outcomes in Patients with Stroke-Associated Pneumonia? A Registry Cohort Study in England and Wales.

INTRODUCTION: It is not known whether modern stroke unit care reduces the impact of stroke complications, such as stroke-associated pneumonia (SAP), on clinical outcomes. We investigated the relationship between SAP and clinical outcomes, adjusting for the confounding effects of stroke care processes and their timing. METHODS: The Sentinel Stroke National Audit Programme provided patient data for all confirmed strokes between April 2013 and December 2018. SAP was defined as new antibiotic initiation for suspected pneumonia within the first 7 days from stroke admission. We compared outcomes after SAP versus non-SAP in appropriate multilevel mixed models. Each model was adjusted for patient and clinical characteristics, as well as markers of stroke care and their timing within the first 72 h. The appropriate effect estimates and corresponding 95% confidence intervals (CIs) were reported. RESULTS: Of 201,778 patients, SAP was present in 14.2%. After adjustment for timing of acute stroke care processes and clinical characteristics, adverse outcomes remained for SAP versus non-SAP patients. In these adjusted analyses, patients with SAP maintained an increased risk of longer length of in-hospital stay (IRR of 1.27; 95% CI: 1.25, 1.30), increased odds of worse functional outcome at discharge (OR of 2.9; 95% CI: 2.9, 3.0), and increased risk of in-hospital mortality (HR of 1.78; 95% CI: 1.74, 1.82). CONCLUSION: We show for the first time that SAP remains associated with worse clinical outcomes, even after adjusting for processes of acute stroke care and their timing. These findings highlight the importance of continued research efforts aimed at preventing SAP.

The Timing of Stroke Care Processes and Development of Stroke Associated Pneumonia: A National Registry Cohort Study.

Introduction: Timely stroke care can result in significant improvements in stroke recovery. However, little is known about how stroke care processes relate to complications such as the development of stroke associated pneumonia (SAP). Here we investigated associations between stroke care processes, their timing and development of SAP. Methods: We obtained patient-level data from the Sentinel Stroke National Audit Programme for all confirmed strokes between 1st April 2013 and 31st December 2018. SAP was identified if new antibiotic initiation for pneumonia occurred within the first 7 days of admission. Time to key stroke care processes in the pre-hospital, hyperacute and acute phase were investigated. A mixed effects logistic regression model estimated the association between SAP [Odds ratios (OR) with 95% CI] and each process of care after controlling for pre-determined confounders such as age, stroke severity and comorbidities. Results: SAP was identified in 8.5% of 413,133 patients in 169 stroke units. A long time to arrival at a stroke unit after symptom onset or time last seen well [OR (95% CI) = 1.29 (1.23-1.35)], from admission to assessment by a stroke specialist [1.10 (1.06-1.14)] and from admission to assessment by a physiotherapist [1.16 (1.12-1.21)] were all independently associated with SAP. Short door to needle times were associated with lower odds of SAP [0.90 (0.83-0.97)]. Conclusion: Times from stroke onset and admission to certain key stroke care processes were associated with SAP. Understanding how timing of these care processes relate to SAP may enable development of preventive interventions to reduce antibiotic use and improve clinical outcomes.