Propensity matching cannot substitute for randomization in albumin studies

Excerpt

Large randomized trials such as the Albumin Italian Outcome Sepsis (ALBIOS) trial involving 1,818 patients with severe sepsis have revealed no evidence of acute kidney injury (AKI) attributable to albumin infusion [1]. Such results are difficult to reconcile with an association between albumin and AKI in the retrospective study by Frenette and colleagues of 984 cardiac surgery patients receiving 6% hydroxyethyl starch 130/0.4, 10% pentastarch, 5% albumin and/or 25% albumin in unspecified combinations [2]. Those investigators criticize the ALBIOS trial for a lack of data on timing of AKI in relation to albumin infusion, but that is also among the shortcomings of their own study. Baseline data are not stratified by colloid group, so imbalances cannot be assessed. The dose–response analysis is univariate only. The propensity matching did not include known independent risk factors for AKI such as preoperative hypoalbuminemia [3] and cardiac catheterization [4]. Furthermore, the matching failed to achieve satisfactory balance, since there remained a significant difference in concomitant pentastarch dose. …