In-Hospital Mortality Risk Increases With DIDO Time for STEMI Patients



Only 11% of patients with ST-elevation myocardial infarction who presented at a hospital without acute percutaneous coronary intervention capability got in and out of the referral hospital within the recommended benchmark of 30 minutes or less, in a retrospective analysis of 14,821 patients.

Moreover, STEMI patients who had a door-in to door-out (DIDO) time of more than 30 minutes had significantly higher in-hospital mortality of 5.9% compared with 2.7% for patients with a DIDO time of 30 minutes or less.

This mortality risk remained significant even after adjustment for differences in baseline patient characteristics and presenting features (adjusted odds ratio 1.56), Dr. Tracy Y. Wang and her associates reportedin the June 22/29 issue of JAMA (2011;305:2540-7).

"DIDO time is a useful performance measure attributable to STEMI referral hospitals that can be used to assess and iteratively improve effectiveness of regional STEMI networks and may further emerge as a quality benchmark to ascertain performance and accountability," the authors wrote.

They go on to suggest that "further attention and improvement of this performance measure will translate into substantial improvement in the timeliness of primary PCI and clinical outcomes for transferred STEMI patients."

Hospitals typically focus on shortening overall door-to-balloon (DTB) times as a way to improve the outcomes of STEMI patients, but little has been known about the impact of DIDO times as a component of the interhospital transfer process. DIDO times are increasingly being advocated as a new quality of care metric for transferred STEMI patients, with a national benchmark of 30 minutes or less recommended by the 2008 American College of Cardiology/American Heart Association performance measures for acute myocardial infarction (J. Am. Coll. Cardiol. 2008;52:2046-99).

Dr. Wang and her associates identified 14,821 STEMI patients transferred to 298 STEMI receiving hospitals for primary PCI in the ACTION (Acute Coronary Treatment and Intervention Outcomes Network) Registry–Get With the Guidelines during January 2007–March 2010. The median DIDO time was 68 minutes (interquartile range 43-120 minutes).

Only 11% (1,627) of patients had a DIDO time of 30 minutes or less, while 56% had a DIDO time greater than 60 minutes, and more than one-third (35%) had a DIDO time greater than 90 minutes, reported Dr. Wang of Duke Clinical Research Institute, Durham, N.C.

Patients with a DIDO time of more than 30 minutes were significantly more likely than were those with shorter DIDO times to be older; to be female; to have comorbidities such as hypertension, diabetes, and prior heart failure or stroke; and to present during off hours. A left bundle branch block or signs of posterior MI on the presenting ECG were also more common in those with prolonged DIDO times.

Notably, only a minority of patients with a prolonged DIDO time had contraindications to fibrinolytic therapy, which is the preferred reperfusion strategy for STEMI when access to timely primary PCI is not a viable option, Dr. Wang pointed out.

The percentage of patients achieving the guideline-recommended overall DTB time of 90 minutes or less was significantly higher for patients with a DIDO time of 30 minutes or less, compared with patients with a DIDO time greater than 30 minutes (60% vs. 13%), she reported. Median DTB times were significantly shorter at 85 minutes vs. 127 minutes, respectively.

The observed in-hospital mortality rate was 5.5% during the study period. The median length of hospitalization was 3 days among all patients.

Using patients with a DIDO time of 30 minutes or less as the reference, risk adjusted mortality increased as DIDO times lengthened from a range of 31-60 minutes (OR 1.34) to 61-90 minutes (OR 1.41) and beyond 90 minutes (OR 1.86).

"Our results underscore the importance of optimizing regional and statewide networks for STEMI systems of care," Dr. Wang wrote.

Most American hospitals lack round-the-clock PCI capacity, although a substantial proportion of contemporary STEMI patients require interhospital transfer for primary PCI. An analysis reported earlier this year by the same group revealed that between 2005 and 2007, fewer than 10% of transferred patients with STEMI met the metric of overall DTB time of less than 90 minutes (Am. Heart J. 2011;161:76-83, e1).

Finally, the current analysis is not without a sliver of good news. The researchers observed that overall DTB time has further improved for transferred patients with STEMI, with about 1 in 5 patients treated within a DTB time of less than 90 minutes. The proportion of patients with a DIDO time of 30 minutes or less also showed improvement over time, with median DIDO times falling from 90 minutes in January 2007 to 58 minutes in March 2010.


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