A new UCLA study reveals that a widely used federal hospital safety metric is fundamentally flawed when applied to emergency stroke care, potentially creating incentives that may discourage hospitals from performing lifesaving procedures for the sickest patients.
The research , published in the Journal of NeuroInterventional Surgery, examined Patient Safety Indicator 04 (PSI 04), a "failure-to-rescue" measure developed by the U.S. Agency for Healthcare Research and Quality (AHRQ) to track deaths following treatable complications in surgical patients. The study analyzed data from the Nationwide Inpatient Sample covering 73,580 stroke thrombectomy procedures between 2016-2019, along with detailed reviews of consecutive cases at UCLA.
While stating the metric is appropriate for elective procedures performed on relatively healthy patients, the study found the metric is inappropriate for endovascular thrombectomy, an emergency procedure to remove blood clots in stroke patients who are already gravely ill upon admission.
"This metric was designed to identify preventable deaths, but when applied to emergency stroke care, it's flagging unavoidable complications of severe strokes rather than problems with the procedure itself," said Dr. Melissa Marie Reider-Demer , the study's first author and UCLA Health DNP. "The unintended consequence is that hospitals providing excellent stroke care to the sickest patients may appear to have poor safety records."
PSI 04 is triggered when patients develop any of five complications after a procedure (pneumonia, blood clots, sepsis, shock/cardiac arrest, or gastrointestinal bleeding) and subsequently die in the hospital. The metric is used nationally for public reporting, hospital quality ratings and pay-for-performance programs by Medicare and influential organizations like the Leapfrog Group.
The UCLA team analyzed both national data and detailed case reviews to assess the metric's appropriateness for stroke care. Their findings included:
- PSI 04 occurred in 20.5% of stroke thrombectomy patients nationally, which is one to three orders of magnitude higher than all other 17 patient safety indicators (median: 0.10%)
- The rate for stroke procedures was far higher than the 14.3% rate for all surgical procedures combined
- Among the 18 federal patient safety indicators, PSI 04 for all procedures had by far the highest event rate, suggesting the metric may be fundamentally problematic
At UCLA's Comprehensive Stroke Center, researchers examined every thrombectomy case flagged by PSI 04 between 2016-2018. An expert panel of neurointerventionalists and neurologists reviewed each case and found:
- All patient deaths were related to complications of the severe presenting stroke, not the thrombectomy procedure
- EVT procedures accounted for 7.2% of neurosurgical PSI 04 flags despite representing only 1.5% of neurosurgical procedures
- Not a single case represented an actual preventable safety concern
The study authors found the metric is flawed for two key reasons when applied to stroke thrombectomy:
- The complications it tracks are common consequences of severe strokes themselves, not the procedure. Patients arriving with massive strokes are at high risk for pneumonia, blood clots, and other complications regardless of treatment.
- Stroke patients are already critically ill before the procedure, unlike patients undergoing elective surgeries. Even when complications arise, these gravely ill patients have far less resilience to survive them compared to relatively healthy surgical patients.
"We're essentially penalizing hospitals for trying to save patients who are already dying from stroke," Dr. Reider-Demer said. "These procedures give severely affected patients their only chance at survival or functional recovery, but the current metric makes it look like the hospitals are providing poor care."
Unintended Consequences
The researchers warn that inappropriate safety metrics can create harmful incentives. Previous research has shown that public reporting of surgical mortality rates led some heart surgeons to cherry-pick healthier patients to protect their performance ratings, limiting access for the sickest patients who need care most.
"There's a real concern that hospitals might be discouraged from performing thrombectomy on the most severe stroke patients, or that stroke centers with high volumes of critically ill patients could be unfairly penalized in quality ratings and reimbursement," said Dr. Jeffrey Saver , the study's senior author and vice chair for Clinical Research and the Carol and James Collins Chair of the Department of Neurology at UCLA Health.
This issue has become more pressing as recent clinical trials have expanded thrombectomy to patients with even larger strokes, who have high mortality rates even with intervention though still lower than without it.
A Path Forward
The Centers for Medicare & Medicaid Services has proposed revising PSI 04 to exclude patients with acute conditions like stroke coded as the principal reason for admission, with implementation planned for fiscal year 2027.
In Dr. Saver's view, the revision addresses important shortcomings.
"This revision makes sense from a clinical perspective," Dr. Saver said. "The current metric doesn't identify preventable events in stroke care and has the potential to mislead the public about hospital quality while creating incentives that could harm the sickest patients."
