Assessment of diagnostic strategies based on risk stratification for aneurysmal subarachnoid hemorrhage: a retrospective chart review

Abstract

Background and importance: Current guidelines recommend noncontrast computed tomography (NCCT) followed by lumbar puncture for the diagnosis of subarachnoid hemorrhage (SAH). Alternative strategies, including clinical risk stratification and CT angiography (CTA), are emerging.

Objective: To evaluate alternative strategies to current guidelines through clinical risk stratification.

Design, setting and participants: Single-site, retrospective observational study of patients with SAH suspicion, from 2011 to 2016. We combined results of each investigation (NCCT, CTA and lumbar puncture) with a clinical risk assessment, including Ottawa score.

Exposure: Comparing the current strategy (NCCT ± lumbar puncture if negative CT) to alternative strategies (NCCT + CTA ± lumbar puncture if high clinical risk or negative CT and onset of headache ≥12 h o dds ratio ≥24 h).

Outcome measure and analysis: Main outcome was diagnosis of SAH at hospital discharge. Secondary outcomes were death from all causes and need for invasive procedures at 28 days. We used sensitivity, specificity, positive predictive value and negative predictive value (NPV) to evaluate the diagnostic performance of three strategies.

Main results: 310 patients were included. SAH was diagnosed in 8 cases (2.6%), none died and 7 (2.2%) had a surgical procedure. Performances of different strategies were not statistically different. NPVs were 99.7% [95% Confidence interval (CI), 98.2-100%] for strategy 1 and 100% (95% CI, 98.8-100%) for strategies 2 and 3. More than 4000 lumbar punctures are needed to diagnose one SAH when CTA is performed within 24 h of symptoms' onset and absence of high-risk criteria.

Conclusion: Clinical risk stratification and CTA strategy are well-tolerated and effective for diagnosis of SAH, avoiding systematic use of lumbar puncture.