Introduction: Encephalitis, acute inflammation of the brain, correlates with systemic complications, prolonged ICU stays, and high mortality. Cerebrovascular disease (CVD) involves reduced blood flow to the brain. The impact of CVD on outcomes of critically-ill encephalitis patients has not been well characterized. We hypothesized that compromised cerebrovascular integrity in CVD exacerbates the impact of cerebral inflammation and critical illness. Methods: We used publicly available data to conduct a population-based cohort study of adults admitted to intensive care units of acute care hospitals in Texas from 2016 through 2022 with encephalitis. Transfers, elective admissions, and discharges against medical advice were excluded. The population was identified using International Classification of Diseases, Tenth Revisions, Clinical Modification (ICD-10-CM) codes selected from Clinical Classification Software Refined Category NVS002: Encephalitis. CVD was identified using ICD-10-CM codes G45x, G46x, I60x-I69X, and H340x. The outcome was short-term mortality. Overlap propensity score weighting was applied with results expressed as adjusted risk ratio and 95% confidence interval (aRR 95% CI). Results: Of 6,576 hospitalizations included in the study, 1,496 (23%) had CVD. Hospitalizations with CVD were older (48% vs 38% aged ≥ 65 years), had higher Deyo comorbidity index (meanSD 2.3 2.2 vs 2.1 2.4), and more often required invasive mechanical ventilation (38% vs 28%). Patients with CVD had a higher rate of short-term mortality (28% vs 17%). Hospital length of stay was longer for CVD patients (meanSD 1919 days vs 1619 days). All covariates balanced exactly after overlap weighting. Within the overlap population, CVD remained associated with mortality (26% vs 22%) and (aRR 1.2 95% CI 1.1 to 1.3). Similar results were observed on sensitivity analyses for older patients, patients using invasive mechanical ventilation, and those more severely ill. Conclusions: Although CVD patients were older, had higher burden of comorbidities, and were at greater risk of death, after risk adjustment, preexisting CVD was still found to significantly and independently increase the risk of death in critically ill patients with encephalitis. These findings can help with early risk stratification.
Archer et al. (Sun,) studied this question.