Outcomes and Mortality Prediction Model of Critically Ill Adults With Acute Respiratory Failure and Interstitial Lung Disease

Abstract

Background: We aimed to examine short- and long-term mortality in a mixed population of patients with interstitial lung disease (ILD) with acute respiratory failure, and to identify those at lower vs higher risk of in-hospital death.

Methods: We conducted a single-center retrospective cohort study of 126 consecutive adults with ILD admitted to an ICU for respiratory failure at a tertiary care hospital between 2010 and 2014 and who did not undergo lung transplantation during their hospitalization. We examined associations of ICU-day 1 characteristics with in-hospital and 1-year mortality, using Poisson regression, and examined survival using Kaplan-Meier curves. We created a risk score for in-hospital mortality, using a model developed with penalized regression.

Results: In-hospital mortality was 66%, and 1-year mortality was 80%. Those with connective tissue disease-related ILD had better short-term and long-term mortality compared with unclassifiable ILD (adjusted relative risk, 0.6; 95% CI, 0.3-0.9; and relative risk, 0.6; 95% CI, 0.4-0.9, respectively). Our prediction model includes male sex, interstitial pulmonary fibrosis diagnosis, use of invasive mechanical ventilation and/or extracorporeal life support, no ambulation within 24 h of ICU admission, BMI, and Simplified Acute Physiology Score-II. The optimism-corrected C-statistic was 0.73, and model calibration was excellent (P = .99). In-hospital mortality rates for the low-, moderate-, and high-risk groups were 33%, 65%, and 96%, respectively.

Conclusions: We created a risk score that classifies patients with ILD with acute respiratory failure from low to high risk for in-hospital mortality. The score could aid providers in counseling these patients and their families.

Keywords: idiopathic interstitial pneumonia; idiopathic pulmonary fibrosis; intensive care; interstitial lung disease; respiratory failure.

Figure 1

Kaplan-Meier 1-year survival curves from the time of hospitalization for acute respiratory failure for categories of interstitial lung disease. CTD-ILD = connective tissue disease-related ILD; ILD = interstitial lung disease; IPF = idiopathic pulmonary fibrosis; uILD = unclassifiable ILD. P value is for the log-rank test.

Figure 2

A, Frequency distribution of patients by predicted risk of in-hospital mortality based on the low-, moderate-, and high-risk score. B, Kaplan-Meier 1-year survival curves from the time of hospitalization for acute respiratory failure by low-, medium-, and high-risk categories. P value is for the log-rank test.