Clinicians underestimate severity of ischemic stroke next to ICH

Research published in Stroke Jan. 10 suggests clinicians overestimate the severity of intracerebral hemorrhage (ICH) and underestimate the severity of acute ischemic stroke (AIS), resulting in a bias that could influence patients’ outcomes and treatment plans.

ICH has a considerably poorer prognosis than AIS, corresponding author Keith W. Muir, MD, of the Institute of Neuroscience and Psychology at the University of Glasgow, and coauthors wrote in the journal. One-month mortality after ICH is around four times higher than one-month mortality after AIS, and survival after ICH is 46 percent after one year, with 75 percent of patients either deceased or severely disabled.

ICH is also far more conspicuous on acute CT than AIS, Muir and colleagues said, which, married with a negative perception of ICH, might lead clinicians to overestimate the severity of ICH cases and influence their prognostic evaluation.

“Clinical underestimation of the chances of favorable outcome in severe ICH cases may prompt clinicians to limit intensive management strategies and lead to early implementation of end-of-life protocols, with the inevitable consequence of higher mortality among these patients,” the authors wrote. “Prognosis may, therefore, be biased as a consequence of clinical perception.”

Muir et al. recruited clinicians to evaluate 66 CT scans from patients with either acute ICH (33) or ischemic stroke (33) with the goal of determining whether clinicians’ estimates of volume, severity and prognosis from acute imaging differ between ICH and AIS cases. ICH cases were matched with AIS cases for lesion volume based on acute CT for ICH and 24-hour CT for AIS.

An average of eight readers, all blind to any clinical information, interpreted each scan. Each was asked to estimate lesion volume to the nearest 5 mL, grade lesion severity on a scale from 1 to 5 and estimate 30-day prognosis using the modified Rankin Scale.

The researchers found that in 33 ICH/AIS comparisons, clinicians overestimated ICH volume by an average 8 mL and underestimated AIS volume by an average 8 mL. Observers rated ICH to be of greater severity and poorer prognosis than AIS cases—41 percent of ICH cases were rated as either severe or very severe, while just 14 percent of AIS cases were rated the same. Forty-seven percent of ICH cases and 74 percent of AIS cases fell between 0 and 2 on the Rankin Scale.

Even after adjusting for estimated volumes, the estimated severity and prognosis for ICH remained significantly worse compared to AIS.

“Using CT scans matched for lesion volume, we found that clinicians significantly overestimated the volume of ICH and underestimated the volume of AIS,” Muir and coauthors wrote. “In addition, clinicians estimated clinical severity to be significantly greater for ICH and predicted less likelihood of favorable 30-day outcomes for ICH compared with AIS, even after adjusting for estimated lesion volume and independent of radiological features including midline shift and ventricular effacement.”

The team said the results confirmed their hypothesis that a bias exists among clinicians interpreting these conditions.

“Our results suggest that a bias is present among clinicians in assessing stroke severity and prognosis for ICH compared with AIS,” they wrote. “This may be of importance because outcomes are significantly affected by acute management, including end-of-life decisions or delays in secondary preventative treatment or rehabilitation.”