# Survival after wake-up stroke and unknown-onset stroke—a nationwide observational study from the Norwegian Stroke Registry

## TL;DR

This study examines survival rates after different types of strokes in Norway, finding that unknown-onset strokes are linked to worse long-term survival.

## Contribution

The study provides new insights into survival differences between wake-up and unknown-onset strokes using nationwide data.

## Key findings

- Short-term survival rates were similar across all stroke types.
- Unknown-onset stroke was associated with higher long-term mortality compared to known-onset stroke.
- Wake-up stroke showed no significant difference in long-term survival compared to known-onset stroke.

## Abstract

The risk of death increases significantly after stroke as shown in previous studies from the general stroke population; however, specific knowledge regarding survival after wake-up stroke and unknown-onset stroke is lacking. We aimed to report short- and long-term survival after ischaemic stroke, by mode of onset, using data from a high-quality nationwide stroke registry.

Data from the Norwegian Stroke Registry for the period 2014-2023 were retrieved to assess short- and long-term survival after first-ever ischaemic stroke. Short-term survival was defined as surviving the first 30 days after stroke, and long-term survival was examined in 30-day survivors. Kaplan–Meier survival probabilities were estimated at 30 days, 1, 3 and 5 years after stroke for all patients and stratified by mode of onset: known-onset stroke, wake-up stroke and unknown-onset stroke. The relationship between mode of onset and all-cause mortality was assessed using multivariable regression models.

Of the 68,025 patients included, 45,084 had known-onset stroke, 12,429 wake-up stroke and 10,512 unknown-onset stroke. The 30-day survival rate was 91.3% for known-onset stroke, 92.4% for wake-up stroke and 91.7% for unknown-onset stroke, while 5-year survival rate among 30-day survivors was 65.4%, 67.6% and 60.4%, respectively. For 30-day survivors, using known-onset stroke as reference group, the adjusted HR for all-cause mortality in the total observation period for wake-up stroke was 0.99 (95% CI, 0.95–1.04), P = .778 and for unknown-onset stroke the HR was 1.19 (95% CI, 1.14–1.25), P < .001.

Short-term survival was similar across all modes of onset, while unknown-onset stroke was associated with poorer long-term survival.

Graphical Abstract