Survival After Long-Term Residence in an Intensive Care Unit
Quality-of-Life Survey
The authors successfully contacted 32 of the 39 patients who lived at least 1 year after discharge after an ICU stay of more than 14 days. The subgroups’ median SF-36 scores were similar: 57 for medical patients and 51 for surgical patients. These average scores over 8 domains are similar to those reported by Graf and colleagues for 9 months after ICU discharge (53.7) and are lower than the normative data reported by those authors for the German population (mean, 66.5).29
Discussion
The goals of the present study were 2-fold—to gain a better understanding of the survival and functioning of patients after ICU residence and to define what may constitute a trial of therapy in ICU, or specifically to determine whether there is a particular ICU interval or point at which further care fails to improve survival. The study also compared medical and surgical subpopulations.
The main finding of this study was a 4-fold difference between ICU mortality and 1-year mortality. This mortality increase occurred in both medical and surgical patients, but there were large differences in magnitude between these groups. The survival rates generally were better than those of other general intensive care populations, though such a comparison should be made with caution, as survival differs by country, population, admitting practices, and a variety of other hospital characteristics.30,31 Although some findings of the present study may relate to its largely male U.S. veteran population, the authors believe they have provided a data-collection-and-analysis model that can be used by any hospital trying to understand the course and outcome of its ICU patients and recognizing the value of this knowledge in discussions on goals of care.
Mortality and LOS
As each interval of ICU residence was associated with a stepwise increase in mortality, there was no clear cutoff for diminishing return. To create a reference point, the authors analyzed the data of patients who were in an ICU more than 14 days—thinking that this duration may represent an outer limit of a reasonable trial of therapy and a measure that probably distinguishes acute from chronic critical illness.32 Use of this interval represented a conservative approach, as only 6.5% of the patients in this cohort had a LOS of more than 14 days. This small percentage of patients accounted for 45% of total bed occupancy in this study and 54% of all medical bed occupancy. In the more-than-14-days group, mortality was 37.5% for surgical patients and 46.3% for medical patients. Thus, LOS may be a dynamic measure of physiologic reserve and disease severity—reflecting variables such as response to therapy, severity of comorbidities, resistance to new problems, and rebound from chronic stress, inflammation, and catabolism. This view is supported by the nearly 2-fold higher mortality in medical patients and nearly 3-fold higher mortality in surgical patients in comparison with MPM-III predictions.
Twelve percent of all patients were admitted to ICU multiple times, and these admissions accounted for 25% of all bed occupancies. Multiple admissions indicate a high disease burden or a low physiologic reserve that prevents full recovery from critical illness. As mortality was higher in patients with multiple admissions, ICU readmission should be regarded as a marker for poor overall recovery and should prompt consideration of both initial discharge criteria and trajectory as well as goals of care.
Medical vs Surgical Patients
In this cohort, medical and surgical patients were distinguished on several grounds. Despite the similar mean age of these subpopulations, medical patients had longer LOS and higher short- and long-term mortality. These findings are not surprising, as medical patients in the ICU have high rates of end-stage disease, malignancy, and high comorbidity burden and are often admitted to have potentially life-ending conditions stabilized. Surgical patients generally are selected on their ability to withstand major systemic perturbations—palliative and emergency operations excepted—and generally have medical conditions optimized before surgery. As the expectation of postoperative survival likely biases clinician behavior toward aggressive care, some short-term survival may reflect this behavior.
In contrast, such biased behavior is not an issue in 1-year survival, which instead accurately reflects underlying health. The different slopes of medical and surgical patients on age-vs-mortality in Figures 4A & 4B indicate the different physiologic makeups of these ICU patients. With short and long LOS compared, the difference between surgical and medical patients in the ICU is striking: Sixty-one percent of all surgical bed days vs 45% of all medical bed days are for LOS less than 14 days. Nevertheless, chronic critical illness has a significant impact on both medical and surgical patients and tends to equalize some of the survival differences between these groups. These populations had similar ICU readmission rates as well as similar higher mortality rates for LOS of more than 14 days and especially for LOS of more than 1 month. With longer LOS, the survival curve of surgical patients begins to resemble that of medical patients—suggesting that the phenotype of chronic critical illness becomes the dominant force influencing survival and function (Figures 3A & 3B). Indeed, for surgical patients, the highest mortality categories were ICU readmission and LOS of more than 30 days.
