Mechanical Ventilation
Albumin and C-reactive protein have prognostic significance in patients with community-acquired pneumonia

https://doi.org/10.1016/j.jcrc.2010.10.007Get rights and content

Abstract

Purpose

This study aims to determine the association of commonly used biochemical markers, such as albumin and C-reactive protein (CRP), with mortality and the prognostic performance of these markers combined with the pneumonia severity index (PSI) for mortality and adverse outcomes in patients with community-acquired pneumonia (CAP).

Materials and Methods

The data were gathered prospectively for patients hospitalized with CAP via the emergency department. Laboratory values, including CRP and albumin, clinical variables, and the PSI were measured. Primary outcomes were 28-day mortality and survival times. Secondary outcome was admission to the intensive care unit, vasopressor use, or the need for mechanical ventilation during the hospital stay.

Results

A total of 424 patients were included. The 28-day mortality was 13.7%. C-reactive protein and albumin were significantly different between survivors and nonsurvivors. In logistic regression analysis, CRP and albumin were independently associated with 28-day mortality (P < .05). Receiver operating characteristic curves showed improved mortality prediction by adding CRP or albumin to the PSI scale. The Cox proportional hazards analysis showed that high serum albumin (≥3.3 mg/dL) had a hazard ratio of 0.5 (95% confidence interval, 0.3-0.9), and high CRP (≥14.3 mg/dL) had a hazard ratio of 2.0 (95% confidence interval, 1.1-3.4). For predicting secondary outcome, adding albumin to PSI increased areas under the curve significantly, but CRP did not.

Conclusion

Albumin and CRP were associated with 28-day mortality in hospitalized patients with CAP, and these markers increased prognostic performance when combined with the PSI scale.

Introduction

Community-acquired pneumonia (CAP) is an important cause of morbidity and mortality throughout the world [1]. Some severity assessment tools such as the pneumonia severity index (PSI), CURB65 (confusion, urea nitrogen, respiratory rate, blood pressure, ≥65 years of age), or CRB65 (confusion, respiratory rate, blood pressure, ≥65 years of age) have been developed and validated [2], [3]. However, although these scales have been useful in identifying low-risk patients who can be discharged from the emergency department (ED), they have been appraised less accurate in assessing the prognosis for mortality, the need for intensive care unit (ICU) care, and the need for mechanical ventilation in hospitalized patients with CAP [4], [5].

Many biochemical markers are associated with the outcome of CAP, such as the cytokines like tumor necrosis factor α and interleukin 6, C-reactive protein (CRP), procalcitonin, and d-dimer [6], [7], [8], [9]. Of those, CRP, which is a commonly tested laboratory value in hospitalized patients, is an acute phase reactant considered as a potentially important prognostic variable [10], [11].

Serum albumin, which is also a commonly tested laboratory value in hospitalized patients, has been proposed as a reliable predictor of outcome in critically ill patients with infectious diseases [12], [13]. Low serum albumin level also has been associated with morbidity and mortality in various diseases [14], [15], [16], [17], [18]. The precise mechanism of the protective effects of albumin is not known. However, in animal experiments, human serum albumin has been shown to have some protective effects, such as improvement of arterial hyporeactivity in endotoxemia as an antioxidant, reduced ischemia-reperfusion injury, and antiinflammatory effects [18], [19], [20], [21].

The objectives of this study are to identify the association of biochemical markers such as CRP and albumin with mortality and to determine the prognostic significance of these markers combined with PSI for mortality and major adverse outcomes, such as the need for ICU admission, mechanical ventilation, or vasopressor use in hospitalized patients with CAP. We hypothesized that albumin and CRP would be associated with 28-day mortality and improve mortality prediction in hospitalized patients with CAP.

Section snippets

Study setting

A prospective observational study was performed in a 950-bed tertiary academic hospital with an annual ED census of 67 000. The institutional review board of our institute approved the study.

Study design and population

We prospectively collected data of patients who visited our ED and were subsequently hospitalized for CAP between April 2008 and March 2010. Community-acquired pneumonia was defined as a pulmonary infiltrate on the chest radiograph and symptoms consistent with pneumonia, including cough, dyspnea, fever,

Results

During the study period, 424 patients were hospitalized via the ED for CAP. The inclusion criterion was hospitalized patients for CAP via ED, and there were no missing data during the study period. Thus, all patients were included for analysis. Mean (SD) age was 70.4 (15.6) years, and 148 patients (35%) were male. The 28-day mortality was 13.7% (58 patients). The demographic characteristics and initial severity are shown in Table 1. Patients who died were older; had a lower rate of chronic

Discussion

In hospitalized patients with CAP, the initial value of serum albumin and CRP was strongly and independently associated with 28-day mortality, and the addition of serum albumin or CRP concentrations to PSI improved mortality prediction compared with the PSI scale alone. Low serum albumin concentration and high CRP value were also associated with reduced survival of patients with CAP. For predicting ICU admission, vasopressor use, or the need for mechanical ventilation, only albumin had an

References (33)

  • EwigS. et al.

    Validation of predictive rules and indices of severity for community acquired pneumonia

    Thorax

    (2004)
  • MenendezR. et al.

    Biomarkers improve mortality prediction by prognostic scales in community-acquired pneumonia

    Thorax

    (2009)
  • HuangD.T. et al.

    Risk prediction with procalcitonin and clinical rules in community-acquired pneumonia

    Ann Emerg Med 52

    (2008)
  • MiraJ.P. et al.

    The role of biomarkers in community-acquired pneumonia: predicting mortality and response to adjunctive therapy

    Crit Care 12 Suppl

    (2008)
  • CastellJ.V. et al.

    Acute-phase response of human hepatocytes: regulation of acute-phase protein synthesis by interleukin-6

    Hepatology

    (1990)
  • Dominguez de VillotaE. et al.

    Association of a low serum albumin with infection and increased mortality in critically ill patients

    Intensive Care Med

    (1980)
  • Cited by (115)

    • The Role of Biomarkers in the Diagnosis and Management of Pneumonia

      2024, Infectious Disease Clinics of North America
    • C-reactive protein to albumin ratio in critical care settings

      2023, Acta Colombiana de Cuidado Intensivo
    • Prognostic value of blood urea nitrogen-to-serum albumin ratio for mortality of pneumonia in patients receiving glucocorticoids: Secondary analysis based on a retrospective cohort study

      2022, Journal of Infection and Chemotherapy
      Citation Excerpt :

      Previous studies have demonstrated that BUN/ALB ratio is associated with mortality in CAP, HAP, and VAP [17–21,35]. In patients with pneumonia, higher BUN levels and lower ALB levels have been consistently associated with higher mortality [9,36,37], which may result from the catabolic state induced by the inflammatory response to infection and dehydrated condition in the patients with pneumonia [17–19,38]. In our study, we demonstrated for the first time, BUN/ALB ratio is a novel predictor for poor prognosis of pneumonia in patients with receiving glucocorticoids alone or glucocorticoids and other immunosuppressants.

    View all citing articles on Scopus
    1

    Equally contributed as a first author.

    View full text