Extracorporeal Membrane Oxygenation Use in Cardiogenic Shock: Impact of Age on In-Hospital Mortality, Length of Stay, and Costs

Abstract

Objectives: Increasing age is a well-recognized risk factor for in-hospital mortality in patients receiving extracorporeal membrane oxygenation for cardiogenic shock, but the shape of this relationship is unknown. In addition, the impact of age on hospital length of stay, patterns of patient disposition, and costs has been incompletely characterized.

Design: Retrospective analysis of the National Inpatient Sample.

Setting: U.S. nonfederal hospitals, years 2004-2016.

Patients: Adults with cardiogenic shock treated with extracorporeal membrane oxygenation (3,094; weighted national estimate: 15,415).

Interventions: None.

Measurements and main results: The mean age of extracorporeal membrane oxygenation recipients was 54.8 ± 15.4 years (range, 18-90 yr). Crude in-hospital mortality was 57.7%. Median time-to-death was 8 days (interquartile range, 3-17 d). A linear relationship between age and in-hospital mortality was observed with a 14% increase in the adjusted odds of in-hospital mortality for every 10-year increase in age (adjusted odds ratio, 1.14; 95% CI, 1.08-1.21; p < 0.0001). Thirty-four percent of patients were discharged alive at a median time of 30 days (interquartile range, 19-48 d). The median length of stay and total hospitalization costs were 14 days (interquartile range, [5-29 d]) and $134,573 ($71,782-$239,439), respectively, both of which differed significantly by age group (length of stay range from 17 d [18-49 yr] to 9 d [80-90 yr]; p < 0.0001 and cost range $147,548 [18-49 yr] to $105,350 [80-90 yr]; p < 0.0001).

Conclusions: Age is linearly associated with increasing in-hospital mortality in individuals receiving extracorporeal membrane oxygenation for cardiogenic shock without evidence of a threshold effect. Median time-to-death is approximately 1 week. One third of patients are discharged from the hospital alive, but the median time-to-discharge is 1 month. Median length of stay ranges from 9 to 17 days depending on age. Hospitalization costs exceed $100,000 in all age groups.

Figure 1:

Cumulative incidence functions plotting times-to-disposition including time-to-discharge from hospital (i.e. length of stay; black line), time-to-death (long dashed line), time-to-transfer to short-term hospital (short dashed line), time-to-discharge home (self-care and home health care; grey line), and time-to-transfer to skilled nursing facility (dotted line). The “Discharge from Hospital (LOS)” curve represents the summation of patients who have experienced death, transfer, or discharge home; as such, plots of these events illustrate the contributions of these individual components to LOS. At day 14 after admission, which represents the median LOS (vertical grey line), 76.4% (1230/1609) of patients had died, 13.6% (219/1609) had been transferred to a short-term hospital, 6.7% (108/1609) had been discharged home, and 3.1% (50/1609) had been transferred to a skilled nursing facility.

Figure 2:

In-hospital mortality by age category.