The effect of plasma homocysteine levels on clinical outcomes of patients with acute lung injury/acute respiratory distress syndrome

Background: Several reports have shown that homocysteine promotes thrombosis by disturbing the procoagulant-anticoagulant balance, whereas alterations in coagulation and fibrinolysis have been suggested as important pathogenetic and prognostic determinants of mortality in acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). The objective of the study was to evaluate the effect of plasma homocysteine levels on the outcomes of patients with ALI/ARDS. Methods: Sixty-nine consecutive ventilated patients with ALI/ARDS were studied. Blood samples were drawn within 3 days of clinical recognition of ARDS. Measurement of plasma homocysteine, vitamin B12, folate, creatinine, protein C and plasminogen-activator inhibitor-1 antigen levels, and genotyping of the methylenetetrahydrofolate reductase gene C677T and A1298C polymorphisms were carried out. The primary outcomes were 28- and 90-day mortality, whereas secondary outcomes included nonpulmonary organ failure-free days, liberation from mechanical ventilation up to day 28, and ventilator-free days during the 28 days after enrollment. Results: In the multivariable analysis, plasma homocysteine concentration adjusted for age, Acute Physiology and Chronic Health Evaluation II score, methylenetetrahydrofolate reductase C677T and A1298C polymorphisms, and levels of plasminogen-activator inhibitor-1 antigen, protein C, creatinine, vitamin B12, and folate was not found to affect significantly mortality at 28 and 90 days (P = 0.39 and P = 0.83, respectively), days without organ failure besides lungs (P = 0.38), the probability of being free from mechanical ventilation at day 28 (P = 0.63), and days without ventilation assistance (P = 0.73). CONCLUSION:: Our data suggest that increased plasma homocysteine levels, either alone or in synergy with other thrombophilic risk factors, do not seem to adversely affect the prognosis in patients with ALI/ARDS. © 2009 Lippincott Williams & Wilkins.