Association between Age and Mortality in Pediatric and Adult Acute Respiratory Distress Syndrome.

Rationale: The epidemiology, management, and outcomes of acute respiratory distress syndrome (ARDS) differ between children and adults, with lower mortality rates in children despite comparable severity of hypoxemia. However, the relationship between age and mortality is unclear. Objective: We aimed to define the association between age and mortality in ARDS, hypothesizing that it would be nonlinear. Methods: We performed a retrospective cohort study using data from two pediatric ARDS observational cohorts ( n  = 1,236), multiple adult ARDS trials ( n  = 5,547), and an adult observational ARDS cohort ( n  = 1,079). We aligned all datasets to meet Berlin criteria. We performed unadjusted and adjusted logistic regression using fractional polynomials to assess the potentially nonlinear relationship between age and 90-day mortality, adjusting for sex, Pa _{O 2} /Fi _{O 2} , immunosuppressed status, year of study, and observational versus randomized controlled trial, treating each individual study as a fixed effect. Measurements and Main Results: There were 7,862 subjects with median ages of 4 years in the pediatric cohorts, 52 years in the adult trials, and 61 years in the adult observational cohort. Most subjects (43%) had moderate ARDS by Berlin criteria. Ninety-day mortality was 19% in the pediatric cohorts, 33% in the adult trials, and 67% in the adult observational cohort. We found a nonlinear relationship between age and mortality, with mortality risk increasing at an accelerating rate between 11 and 65 years of age, after which mortality risk increased more slowly. Conclusions: There was a nonlinear relationship between age and mortality in pediatric and adult ARDS.