Risk of Critical Illness Among Patients With Solid Cancers: A Population-Based Observational Study

Abstract

Importance: Critical illness may be a potential determinant of cancer outcomes and geographic variations, but its role has not been described before.

Objective: To determine the incidence of admission to intensive care units (ICUs) within 2 years following cancer diagnosis.

Design, setting, and participants: This was a retrospective observational study using cancer registry data in 4 datasets from 2000 to 2009 with linked ICU admission data from 2000 to 2011, in the West of Scotland region of the United Kingdom (population, 2.4 million; all 16 ICUs within the region). All 118,541 patients (≥16 years) diagnosed as having solid (nonhematological) cancers. Their median age was 69 years, and 52.0% were women.

Main outcomes and measures: Demographic and clinical variables associated with admission to an ICU and death in an ICU.

Results: A total of 118,541 patients met the study criteria. Overall, 6116 patients (5.2% [95% CI, 5.0%-5.3%]) developed a critical illness and were admitted to an ICU within 2 years. Risk of critical illness was highest at ages 60 to 69 years and higher in men. The cumulative incidence of critical illness was greatest for small intestinal (17.2% [95% CI, 13.3%-21.8%]) and colorectal cancers (16.5% [95% CI, 15.9%-17.1%]). The risk following breast cancer was low (0.8% [95% CI, 0.7%-1.0%]). The percentage who died in ICUs was 14.1% (95% CI, 13.3%-15.0%), and during the hospital stay, 24.6% (95% CI, 23.5%-25.7%). Mortality was greatest among emergency medical admissions and lowest among elective surgical patients. The risk of critical illness did not vary by socioeconomic circumstances, but mortality was higher among patients from deprived areas.

Conclusions and relevance: In this study, about 1 in 20 patients experienced a critical illness resulting in ICU admission within 2 years of cancer diagnosis. The associated high mortality rate may make a significant contribution to overall cancer outcomes.