Fibroproliferative changes on high-resolution CT in the acute respiratory distress syndrome predict mortality and ventilator dependency: a prospective observational cohort study

Abstract

OBJECTIVES: To examine whether the extent of fibroproliferative changes on high-resolution CT (HRCT) scan influences prognosis, ventilator dependency and the associated outcomes in patients with early acute respiratory distress syndrome (ARDS). DESIGN: A prospective observational cohort study. SETTING: Intensive care unit in a teaching hospital. PARTICIPANTS: 85 patients with ARDS who met American-European Consensus Conference Criteria and eligible criteria. INTERVENTIONS: HRCT scans were performed and prospectively evaluated by two independent observers on the day of diagnosis and graded into six findings according to the extent of fibroproliferation. An overall HRCT score was obtained by previously published method. PRIMARY AND SECONDARY OUTCOMES: The primary outcome was 60-day mortality. Secondary outcomes included the number of ventilator-free days, organ failure-free days, the incidence of barotraumas and the occurrence of ventilator-associated pneumonia. RESULTS: Higher HRCT scores were associated with statistically significant decreases in organ failure-free days as well as ventilator-free days. Multivariate Cox proportional hazards model showed that the HRCT score remained an independent risk factor for mortality (HR 1.20; 95% CI 1.06 to 1.36; p=0.005). Multivariate analysis also revealed that the CT score had predictive value for ventilator weaning within 28 days (OR 0.63; 95% CI 0.48 to 0.82; p=0.0006) as well as for an incidence of barotraumas (OR 1.61; 95% CI 1.08 to 2.38; p=0.018) and for an occurrence of ventilator-associated pneumonia (OR 1.46; 95% CI 1.13 to 1.89; p=0.004). A HRCT score <210 enabled prediction of 60-day survival with 71% sensitivity and 72% specificity and of ventilator-weaning within 28 days with 75% sensitivity and 76% specificity. CONCLUSIONS: Pulmonary fibroproliferation assessed by HRCT in patients with early ARDS predicts increased mortality with an increased susceptibility to multiple organ failure, including ventilator dependency and its associated outcomes.