Acute Respiratory Distress Syndrome Subphenotypes Respond Differently to Randomized Fluid Management Strategy

Am J Respir Crit Care Med. 2017 Feb 1;195(3):331-338. doi: 10.1164/rccm.201603-0645OC.


Rationale: We previously identified two acute respiratory distress syndrome (ARDS) subphenotypes in two separate randomized controlled trials with differential response to positive end-expiratory pressure.

Objectives: To identify these subphenotypes in a third ARDS cohort, to test whether subphenotypes respond differently to fluid management strategy, and to develop a practical model for subphenotype identification.

Methods: We used latent class analysis of baseline clinical and plasma biomarker data to identify subphenotypes in FACTT (Fluid and Catheter Treatment Trial; n = 1,000). Logistic regression was used to test for an interaction between subphenotype and treatment for mortality. We used stepwise modeling to generate a model for subphenotype identification in FACTT and validated its accuracy in the two cohorts in which we previously identified ARDS subphenotypes.

Measurements and main results: We confirmed that a two-class (two-subphenotype) model best described the study population. Subphenotype 2 was again characterized by higher inflammatory biomarkers and hypotension. Fluid management strategy had significantly different effects on 90-day mortality in the two subphenotypes (P = 0.0039 for interaction); mortality in subphenotype 1 was 26% with fluid-liberal strategy versus 18% with fluid-conservative, whereas mortality in subphenotype 2 was 40% with fluid-liberal strategy versus 50% in fluid-conservative. A three-variable model of IL-8, bicarbonate, and tumor necrosis factor receptor-1 accurately classified the subphenotypes.

Conclusions: This analysis confirms the presence of two ARDS subphenotypes that can be accurately identified with a limited number of variables and that responded differently to randomly assigned fluid management. These findings support the presence of ARDS subtypes that may require different treatment approaches.

Keywords: acute lung injury; fluid therapy; subphenotype.

MeSH terms

  • Biomarkers / blood
  • Female
  • Fluid Therapy / methods*
  • Humans
  • Logistic Models
  • Male
  • Outcome and Process Assessment, Health Care / statistics & numerical data*
  • Phenotype
  • Positive-Pressure Respiration
  • Randomized Controlled Trials as Topic
  • Respiratory Distress Syndrome / blood
  • Respiratory Distress Syndrome / classification
  • Respiratory Distress Syndrome / mortality
  • Respiratory Distress Syndrome / therapy*


  • Biomarkers