Synergistic impact of low serum albumin on intensive care unit admission and high blood urea nitrogen during intensive care unit stay on post-intensive care unit mortality in critically ill elderly patients requiring mechanical ventilation.

Aims: To identify intensive care unit (ICU) risk factors for post-ICU 6-month (PI6M) mortality in critically ill elderly patients requiring mechanical ventilation (MV).

Methods: The present study was a retrospective observational study carried out in a respiratory ICU from December 2008 to December 2009. Medical records of patients aged ≥70 years and receiving MV were reviewed. Risk factors of PI6M mortality were assessed by multivariate Cox regression.

Results: Of 120 patients enrolled, 46 (38%) died in the PI6M period. As compared with survivors, non-survivors had lower serum albumin levels on ICU admission, lower estimated glomerular filtration rate, higher peak blood urea nitrogen (BUN) levels during ICU stay (ICU-peak BUN), a higher ratio of prolonged steroid use and longer MV length in ICU. Independent risk factors of PI6M mortality were low albumin on admission (hazard ratio [HR] 3.53 per g/dL decrease, 95% CI [1.97-6.33], P<0.001) and high ICU-peak BUN (HR 1.11 per 10-mg/dL increase, [1.04-1.18], P=0.001). The HR for PI6M mortality was 7.88 [2.97-20.91] for patients with both risk factors (albumin ≤2.8 g/dL and ICU-peak BUN >72 mg/dL) as compared with those without. For patients with high ICU-peak BUN (>72 mg/dL), PI6M survival was better for those with a reduction in BUN level to ≤72 mg/dL at ICU discharge than those without.

Conclusions: Low serum albumin level on ICU admission and high BUN level during ICU stay are two independent risk factors, especially their combination, of PI6M mortality in critically ill elderly patients requiring MV. Furthermore, patients with a reduction in high BUN have a better PI6M survival.