Medical Complications After Aneurysmal Subarachnoid Hemorrhage: Analysis of Trends in US Admissions from 2006 to 2022

OBJECTIVES: To analyze trends in the prevalence of medical complications in aneurysmal subarachnoid hemorrhage (aSAH) hospitalizations in the USA over the last decade. METHODS: A serial cross-sectional study was performed using the 2006-2022 National Inpatient Sample. Adult (≥ 18 years) primary aSAH hospitalizations with and without complications were identified using International Classification of Diseases codes. Negative binomial regression models were used to evaluate the associations between complications, individualized hospitalization characteristics, and hospital outcomes. RESULTS: Of 163,349 aSAH hospitalizations over the study period, 68.2% were female. The mean age was 55.6 years, and this increased over time (p-trend < 0.001). The mean National Inpatient Sample Subarachnoid Severity Score was 5.5 [standard error (SE) 0.06] and this also increased over time. Overall, 42.4% of hospitalizations had ≥ 1 medical complication. Urinary tract infections (UTI) (19.4%), pneumonia (15.4%), and sepsis (8.0%) were the most prevalent complications, while acute renal failure (ARF) (7.8%) was the most frequent noninfectious complication. The age- and sex-standardized prevalence of any medical complication remained stable over this study period, but there was marked heterogeneity in prevalence trends by complication type. ARF prevalence increased by nearly 300% [prevalence rate ratio (PRR): 1.04 per year, 95% confidence interval (CI): 1.02-1.04, p < 0.001] and deep venous thrombosis (DVT) prevalence increased by more than 200% (PRR:1.03, 95% CI: 1.01-1.04, p < 0.001) per year, while UTI and sepsis prevalence declined over this time (all p-trend < 0.001). Pneumonia prevalence declined in male only (p-trend < 0.05). Clipping was associated with higher DVT risk (PRR 1.24, 95% CI: 1.13-1.37) but lower gastrointestinal bleeding risk (PRR 1.14, 95% CI: 0.95-1.38) compared with coiling. All complications were significantly linked to poor outcomes (e.g., pneumonia: PRR 1.23, 95% CI: 1.20-1.30). CONCLUSIONS: The prevalence of infectious complications in aSAH has declined over the last decade, but this has been counterbalanced by a troubling increase in ARF and DVT prevalence. Given the strong association of all complications with poor outcomes, future studies focused on mitigating the prevalence of complications are needed to help improve aSAH outcomes.