C-Reactive protein and albumin as prognostic markers in intensive care

Introduction

C-reactive protein (CRP) is an acute-phase protein, the blood levels of which increase rapidly in response to infection, trauma, ischemia, burns, and other inflammatory conditions. Serum albumin decreases in critically ill patients with similar conditions. The use of these blood tests as risk markers or as predictors of organ failure and death has been studied previously [1, 2] and we wished to investigate their applicability to our population.

Methods

A retrospective laboratory result review of 300 consecutive admissions to the Victoria Infirmary ICU was undertaken. Demographic, APACHE II score and outcome data were retrieved from the Ward Watcher system in the ICU. We compared survivors' and nonsurvivors' levels of CRP and albumin on day of admission and looked at correlation with length of stay and duration of mechanical ventilation. Data were analysed using Student's t test and the Pearson correlation coefficient where appropriate.

Results

Complete data were available for 287 patients. Population demographics were as follows - 61% male, mean age 56.4 ± 2.0 years, median APACHE II score 20 (IQR 15 to 27), crude ICU mortality 24.7%. Comparing survivors and nonsurvivors, admission CRP was significantly higher in nonsurvivors (144.7 vs 113.0, P = 0.037) whereas admission albumin was significantly lower in nonsurvivors (21.3 vs 24.7, P = 0.003). Admission CRP correlated positively with length of stay (r = 0.14, P = 0.017) and APACHE II score (r = 0.13, P = 0.03) but did not significantly correlate with duration of mechanical ventilation (r = 0.10, P = 0.103). Admission albumin correlated negatively with length of stay (r = -0.15, P = 0.01), duration of mechanical ventilation (r = -0.15, P = 0.014) and APACHE II score (r = -0.17, P = 0.004).

Conclusions

CRP and serum albumin on admission are both predictors of intensive care mortality. CRP and serum albumin also correlate significantly with other severity markers such as length of stay and duration of mechanical ventilation and also APACHE II score.