Patient survival after in-hospital cardiac arrest improved substantially in recent years, according to a report from a large registry published online Nov. 15 in the New England Journal of Medicine.

Moreover, the rate of clinically significant neurologic disability among survivors has not risen correspondingly; in fact, it also decreased during the same time period, said Dr. Saket Girotra of the University of Iowa Hospitals and Clinics, Iowa City, and his associates.

These gains were found in a study of nearly 85,000 patients treated at 374 hospitals participating in the Get With the Guidelines (GWTG)-Resuscitation registry, a nationwide, hospital-based, quality-improvement registry documenting all cases of confirmed cardiac arrest at member hospitals in which patients received cardiopulmonary resuscitation. If the findings are extrapolated to the roughly 200,000 such events that occur annually in the United States, “we estimate that an additional 17,200 patients survived to hospital discharge in 2009 as compared with 2000. … We also estimate that more than 13,000 cases of clinically significant neurologic disability were avoided,” the investigators said.

They performed the study because numerous quality-improvement efforts to advance resuscitation care have been adopted in recent years, but no study has yet assessed whether they affected survival.

Dr. Girotra and his colleagues restricted their analysis to patients who had cardiac arrests during 2000-2009 while in an intensive care unit or inpatient ward, excluding cases that occurred in operating rooms, procedural suites, or emergency departments, because events in those settings “have distinct clinical circumstances and outcomes.” The study sample comprised 84,625 patients.

The initial cardiac-arrest rhythm was asystole or pulseless electrical activity in 79% and ventricular fibrillation or pulseless ventricular tachycardia in 21%.

The primary outcome of the study was survival to hospital discharge. This was achieved by over 14,000 patients, or 17%.

“There was a significant trend toward increased survival during the study period for all study patients as well as for both rhythm groups. … After adjustment for temporal trends in patient and hospital characteristics, overall survival increased from 13.7% in 2000 to 22.3% in 2009,” the researchers said (N. Engl. J. Med. 2012;367:1012-20 [doi: 10.1056/NEJMoa1109148]).

This gain was seen across all subgroups of patients, regardless of the type of initial heart rhythm, age (younger or older than 65 years), race, or gender. It also remained robust in an analysis restricted to the 85 hospitals that had participated in the GWTG-Resuscitation registry for at least 8 years. This analysis was intended to adjust for the inclusion of centers that were particularly motivated to improve, as compared with other centers.

At the same time, rates of clinically significant neurologic disability among survivors decreased from 32.9% in 2000 to 28.1% in 2009. Rates of severe neurologic disability among survivors did not change significantly over time.

This study was not designed to ascertain the reasons that survival improved over time. However, it was notable that among patients whose initial cardiac rhythm was treatable by defibrillation, improved survival over time was not accompanied by shorter defibrillation times. “This observation suggests that factors other than rapid defibrillation may have accounted for the improvement in survival,” Dr. Girotra and his associates said.

Such factors might include earlier recognition of cardiac arrest, leading to shorter response times; greater availability of trained personnel delivering better (i.e., uninterrupted) chest compressions; and improvements in postresuscitation care, such as therapeutic hypothermia and early cardiac catheterization.

More studies are needed “to better understand which specific factors are responsible for improvements in survival after cardiac arrest, so that survival gains can be consolidated and expanded to all hospitals,” the investigators said.

This study was funded by the American Heart Association. Dr. Girotra’s associates reported ties to Prescription Solutions, United Health Care, Medtronic, Lumen, and St. Jude Medical.