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Observational Study
. 2019 Jan;47(1):15-22.
doi: 10.1097/CCM.0000000000003424.

Risk Factors for 1-Year Mortality and Hospital Utilization Patterns in Critical Care Survivors: A Retrospective, Observational, Population-Based Data Linkage Study

Free PMC article
Observational Study

Risk Factors for 1-Year Mortality and Hospital Utilization Patterns in Critical Care Survivors: A Retrospective, Observational, Population-Based Data Linkage Study

Tamas Szakmany et al. Crit Care Med. .
Free PMC article


Objectives: Clear understanding of the long-term consequences of critical care survivorship is essential. We investigated the care process and individual factors associated with long-term mortality among ICU survivors and explored hospital use in this group.

Design: Population-based data linkage study using the Secure Anonymised Information Linkage databank.

Setting: All ICUs between 2006 and 2013 in Wales, United Kingdom.

Patients: We identified 40,631 patients discharged alive from Welsh adult ICUs.

Interventions: None.

Measurements and main results: Primary outcome was 365-day survival. The secondary outcomes were 30- and 90-day survival and hospital utilization in the 365 days following ICU discharge. Kaplan-Meier curves were plotted to compare survival rates. Cox proportional hazards regression models were used to determine risk factors of mortality. Seven-thousand eight-hundred eighty-three patients (19.4%) died during the 1-year follow-up period. In the multivariable Cox regression analysis, advanced age and comorbidities were significant determinants of long-term mortality. Expedited discharge due to ICU bed shortage was associated with higher risk. The rate of hospitalization in the year prior to the critical care admission was 28 hospitalized days/1,000 d; post critical care was 88 hospitalized days/1,000 d for those who were still alive; and 57 hospitalized days/1,000 d and 412 hospitalized days/1,000 d for those who died by the end of the study, respectively.

Conclusions: One in five ICU survivors die within 1 year, with advanced age and comorbidity being significant predictors of outcome, leading to high resource use. Care process factors indicating high system stress were associated with increased risk. More detailed understanding is needed on the effects of the potentially modifiable factors to optimize service delivery and improve long-term outcomes of the critically ill.

Conflict of interest statement

Conflict of interest:

The authors declare that no conflict of interest exists.


Figure 1
Figure 1. Organisational flowchart of the study
High quality matching: using the Matching Algorithm for Consistent Results in Anonymised Linkage (MACRAL) algorithm to apply deterministic record linkage and probabilistic record linkage methods to the set of linked variables (15); First critical care episode: re-admission episodes during the study period were excluded; Discharged alive: patients who died while on the ICU were excluded; Continuing ICU care: patients who were transferred internally within the same critical care unit were excluded.
Figure 2
Figure 2. 1-year survival probability of patients discharged from the Welsh intensive care units during the study period
Figure 3
Figure 3. Geographical distribution of deaths during the study period
Percentage of death: % of patients who died during the entire study period in a Local Authority area. University Health Board boundaries (consisting of 2 or 3 Local Authorities) are depicted as grey borders. Population details of each Local Authority area is provided in Table S8 in the Supplemental Digital Content.
Figure 4
Figure 4. Factors affecting survival from the multivariate Cox-regression model
WIMD: Welsh Index of Multiple Deprivation; Admission status: unplanned: acute admission from the Emergency Department or the ward; Comorbidity score calculation and organ support definitions are described in the Supplemental Digital Content; Acute hospital: provide a range of acute in-patient and out-patient services, specialist services (including some surgical acute specialties) but not the wide range available in major acute hospitals and may not have 24/7 Emergency Department. LOS: Length of stay; HDU: High dependency unit. Discharge status: specialised critical care transfer: Transferred from critical care unit for tertiary specialist critical care provision; Discharge status: early, critical care bed shortage: Transferred from critical care before deemed clinically ready to lower acuity beds due to ICU capacity reasons; Discharge status: continued critical care transfer: Transferred from critical care unit due to capacity reasons.

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