Clara cell protein 16: A biomarker for detecting secondary respiratory complications in patients with multiple injuries.

BACKGROUND

Clara cell protein 16 (CC16) has recently gained acceptance as a blood biomarker for detecting direct and indirect lung injury. Although the early elevation of CC16 serum levels has been shown to correlate with pulmonary damage in patients with multiple injuries, the subsequent time course of CC16 serum levels has not been investigated in these patients.

METHODS

Fifty-eight patients with multiple injuries, 32 with severe thoracic injury, and 12 healthy volunteers were enrolled in this study. CC16 serum levels were measured at the time they were admitted to the trauma ward "time 0" and subsequently until day 14 using the enzyme-linked immunosorbent assay technique. The correlation between CC16 serum levels and severe lung injury, onset of nosocomial pneumonia, acute respiratory distress syndrome or acute lung injury, and organ failure was measured. In addition, areas under the receiver operating characteristic curve were calculated (p < 0.05 = significant).

RESULTS

In patients with lung injury, initial "time 0" median CC16 values were significantly elevated (11.2 ng/mL) compared with patients without severe thoracic injury (6.9 ng/mL) and controls (6.3 ng/mL). The observed elevation in serum CC16 declined to control values within 12 to 24 hours after trauma unless patients secondarily developed pneumonia. In the latter patients, median CC16 serum levels were significantly elevated (14.5 ng/mL) at the onset of pneumonia compared with their levels (7.3 ng/mL) 1 day before. In contrast, no secondary elevation in CC16 serum levels was observed in patients without severe lung injury within the same 24-hour period. The area under the receiver operating characteristic curve for serum CC16 and pneumonia was 0.79 (0.62-0.97; p = 0.0011).

CONCLUSION

Our results confirm the previously described association between initial elevation in CC16 serum levels and severe thoracic injury in patients with multiple injuries. In addition, we found that the initial elevation in CC16 serum levels declines to control values within the first day after trauma and that a secondary elevation indicates respiratory complications.

LEVEL OF EVIDENCE

Diagnostic study, level II.