Contemporary Analysis of the Volume-Outcome Relationship for Patients With Nontraumatic Subarachnoid Hemorrhage.

Nontraumatic SAH hospitalizations in the 2016-2022 Nationwide Readmissions Database carried a high index mortality of 20.2%.

• The cohort comprised an estimated 142,271 hospitalizations of adults (≥18 years) with a primary diagnosis of nontraumatic SAH.
• Data came from the 2016 to 2022 Nationwide Readmissions Database.
• Index mortality was 20.2%.

Higher SAH admission volume and higher clipping and coiling procedural volume were each independently associated with reduced in-hospital mortality after risk adjustment when modeled separately.

• Multivariable regression models evaluated the independent associations of SAH admission volume and clipping and coiling procedural volume with in-hospital outcomes.
• Each volume metric was associated with lower mortality after risk adjustment.

When admission volume and procedural volume were modeled jointly, clipping and coiling procedural volume remained an independent predictor of mortality while SAH admission volume did not.

• Procedural volume: adjusted odds ratio 0.981 per 10 procedures, P<0.001.
• SAH admission volume was no longer significant in the joint model (P=0.40).
• Procedural caseload was the dominant predictor of in-hospital mortality.

The authors interpret the findings as suggesting that survival benefits historically attributed to SAH admission volume may be more precisely explained by procedural expertise.

• Prior studies showed an inverse association between admission volume and in-hospital mortality, but reported thresholds remain broad.
• The relative importance of admission versus procedural volume had not previously been evaluated on a national scale.
• The authors state that the findings support reexamination of volume-based benchmarks in contemporary cerebrovascular care frameworks.