Chest CT scan and alveolar procollagen III to predict lung fibroproliferation in acute respiratory distress syndrome.

Background: Lung fibroproliferation in ARDS patients is associated with mortality. Alveolar procollagen III (NT-PCP-III) is a validated biomarker of lung fibroproliferation. A chest CT scan could be useful for the diagnosis of lung fibroproliferation. The aim of this study was to identify lung fibroproliferative CT scan aspects in ARDS patients with high levels of NT-PCP-III.

Results: This retrospective study included ARDS patients who had at least one assessment of alveolar NT-PCP-III and a chest CT scan within 3 days before or after NT-PCP-III determination. An alveolar level of NT-PCP-III > 9 µG/L indicated fibroproliferation. The CT scan was scored on interstitial and alveolar abnormalities. Each lobe was scored from 0 to 5 according to the severity of the abnormalities. The crude score and the corrected score (related to the number of scored lobes in cases of important lobar condensation or lobectomy) were used. One hundred ninety-two patients were included, for a total of 228 alveolar NT-PCP-III level and CT scan 'couples'. Crude and corrected CT scan fibrosis scores were higher in the fibroproliferation group compared with the no fibroproliferation group (crude score: 12 [9-17] vs 14 [11-12], p = 0.002; corrected score: 2.8 [2.2-4.0] vs 3.4 [2.5-4.7], p < 0.001). CT scan fibrosis scores and NT-PCP-III levels were significantly but weakly correlated (crude score: ρ = 0.178, p = 0.007; corrected score: ρ = 0.184, p = 0.005).

Conclusions: When the alveolar level of NT-PCP-III was used as a surrogate marker of histological lung fibroproliferation, the CT scan fibrosis score was significantly higher in patients with active lung fibroproliferation. Pulmonary condensation is the main limitation to diagnosing fibroproliferation during ARDS.