Survival has markedly improved for the approximately 200,000 patients who experience in-hospital cardiac arrest (IHCA) in the U.S. each year, but patients who arrest during nights and weekends remain less likely to survive than those who suffer IHCA during “on-hours,” according to a study published Jan. 22 in the Journal of the American College of Cardiology.

“Nearly 50 percent of in-hospital cardiac arrests take place during ‘off-hours,’” lead author Uchenna R. Ofoma, MD, MS, with Geisinger Health System in Danville, Pennsylvania, said in a press release.

“By determining how survival has changed in recent years, we may be able to identify opportunities for quality improvement efforts. If we can improve survival for cardiac arrests that occur during off-hours, it could impact a substantial number of patients.”

Ofoma and colleagues studied 151,071 adults who experienced IHCA from 2000 through 2014. They defined off-hours as 11 p.m. to 6:59 a.m. Monday through Friday or anytime on weekends. On-hours encompassed 7 a.m. to 10:59 p.m. Monday through Friday.

From 2000 to 2014, risk-adjusted survival to discharge improved for both on-hours (16 percent to 25.2 percent) and off-hours IHCA (11.9 percent to 21.9 percent). However, the survival rate remained significantly lower for off-hours versus on-hours—a 3.3 percent absolute difference during the final year of the study. The absolute survival difference peaked at 5.3 percent in 2009.

“While it was encouraging to see that survival has increased in both groups of patients, the persistent survival disparities between on-hours and off-hours remains disheartening,” Ofoma said. “Timing of in-hospital cardiac arrest has a major impact on a patient’s outcome, so we must make this an area to focus quality improvement efforts to ensure that improved survival trends are sustained over time.”

The researchers identified several factors that could explain their findings:

• Hospitals commonly change their staffing patterns on nights and weekends, potentially leading to fewer physicians and experienced staff members being available.
• Physicians who work nights and weekends may care for patients they are less familiar with.
• Nurse-to-patient ratios are lower during off-hours.
• Working nighttime hours has been shown to affect employees’ psychomotor skills and performance of skilled activities such as cardiopulmonary resuscitation.

“These factors likely affect the ability of hospital staff to recognize deteriorating patients, prevent IHCA, or quickly initiate resuscitation, all of which may impact survival,” Ofoma and colleagues wrote. “Factors related to operational processes of early post-arrest diagnostic and therapeutic care (e.g., echocardiography, coronary angiography, mechanical circulatory support), multidisciplinary teams necessary to coordinate and provide such care, and quality of intensive care and nursing, which may influence post-resuscitation survival, are also likely to vary during nights and weekends.”

The authors noted their study only included hospitals in the Get With The Guidelines-Resuscitation registry and may not be generalizable to other hospitals. Also, data on physician and nurse staffing patterns—and whether they changed over the duration of the study—wasn’t available.

In an accompanying editorial, Julia H. Indik, MD, PhD, said the next step for solving this dilemma is identifying the hospitals with the smallest gaps in survival between on- and off-hours patients. By analyzing their systems of care, perhaps researchers can uncover a blueprint for other hospitals to follow, she wrote.