Age and decisions to limit life support for patients with acute lung injury: a prospective cohort study

Abstract

Introduction: The proportion of elderly Americans admitted to the intensive care unit (ICU) in the last month of life is rising. Hence, challenging decisions regarding the appropriate use of life support are increasingly common. The objective of this study was to estimate the association between patient age and the rate of new limitations in the use of life support, independent of daily organ dysfunction status, following acute lung injury (ALI) onset.

Methods: This was a prospective cohort study of 490 consecutive patients without any limitations in life support at the onset of ALI. Patients were recruited from 11 ICUs at three teaching hospitals in Baltimore, Maryland, USA, and monitored for the incidence of six pre-defined limitations in life support, with adjustment for baseline comorbidity and functional status, duration of hospitalization before ALI onset, ICU severity of illness, and daily ICU organ dysfunction score.

Results: The median patient age was 52 (range: 18 to 96), with 192 (39%) having a new limitation in life support in the ICU. Of patients with a new limitation, 113 (59%) had life support withdrawn and died, 53 (28%) died without resuscitation, and 26 (14%) survived to ICU discharge. Each ten-year increase in patient age was independently associated with a 24% increase in the rate of limitations in life support (Relative Hazard 1.24; 95% CI 1.11 to 1.40) after adjusting for daily ICU organ dysfunction score and all other covariates.

Conclusions: Older critically ill patients are more likely to have new limitations in life support independent of their baseline status, ICU-related severity of illness, and daily organ dysfunction status. Future studies are required to determine whether this association is a result of differences in patient preferences by age, or differences in the treatment options discussed with the families of older versus younger patients.

Figure 1

Patient trajectories and outcomes following acute lung injury onset. Percentages in boxes represent the proportion of all 490 patients with the characteristic or outcome. Percentages along the arrows refer to the proportion of patients who transitioned to the outcome described in the box where the arrow terminates. Proportions do not sum to 100% due to rounding. ALI, acute lung injury; CPR, cardiopulmonary resuscitation.

Figure 2

Estimated probability of cardiac arrest, limitation in life support, and ICU discharge, by patient age. Estimated probability of cardiac arrest, limitation in life support, or ICU discharge for a typical patient in this acute lung injury (ALI) cohort (male patient hospitalized for 2 days before ALI onset, without any oncology comorbidity in a medical ICU at hospital site 1 with median values for Acute Physiology and Chronic Health Evaluation II, Functional Comorbidity Index, Charlson Comorbidity Index, and Sequential Organ Failure Assessment scores) at the time of enrollment. The cumulative incidence of each outcome was obtained through estimation using the initial model containing all baseline covariates. The figure has been truncated at 28 days; hence, the cumulative probability of all events does not reach 100% because 11% of patients had their first event more than 28 days after ALI onset. From left to right, the panels present the estimated probability of events when the patient is age 40, 60, and 80.