Circulating levels of pro-atrial natriuretic peptide in lower respiratory tract infections.
OBJECTIVE
To analyse the mid region of plasma N-terminal pro-atrial natriuretic peptide (MR-proANP) levels in patients with lower respiratory tract infections to evaluate its prognostic use for the severity of disease and outcome.


METHODS
Prospective observational study. Setting. Emergency department of a university hospital.


METHODS
A total of 545 consecutive patients with lower respiratory tract infections and 50 healthy controls. Interventions. MR-proANP was measured in serum from all patients using a new sandwich immunoassay.


RESULTS
MR-proANP levels (median [IQR], in pmol L(-1)) were significantly higher in patients with lower respiratory tract infections when compared with controls (138.0 [74.1-279.0] vs. 72.7 [62.5-89.5], P < 0.001), with highest levels in patients with community-acquired pneumonia (CAP). MR-proANP, but not C-reactive protein (CRP) levels, gradually increased with increasing severity of CAP, classified according to the pneumonia severity index (PSI) score (P < 0.001). On admission, MR-proANP levels were significantly higher in nonsurvivors when compared with survivors (293.0 [154.0-633.0] vs. 129.0 [71.4-255.0], P < 0.001). In a receiver operating characteristic (ROC) analysis for the prediction of survival of patients with CAP the area under the ROC curve (AUC) for MR-proANP was 0.69, similar when compared with the PSI (AUC 0.74, P = 0.31), and better when compared with other biomarkers, i.e. procalcitonin (AUC 0.57, P = 0.08), CRP (AUC 0.52, P = 0.02), and leucocyte count (AUC 0.56, P = 0.07).


CONCLUSIONS
MR-proANP levels are increased in lower respiratory tract infections, especially in CAP. Together with other clinical, radiographic and laboratory findings, MR-proANP levels might be helpful for the risk stratification in CAP.
Müller
B
B
Department of Internal Medicine, University Hospital Basel, Basel, Switzerland.
Süess
E
E
Schuetz
P
P
Müller
C
C
Bingisser
R
R
Bergmann
A
A
Stolz
D
D
Tamm
M
M
Morgenthaler
N G
NG
Christ-Crain
M
M
D000208:Acute Disease; D000368:Aged; D009320:Atrial Natriuretic Factor / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001991:Bronchitis / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D002116:Calcitonin / Q000097:blood; D015740:Calcitonin Gene-Related Peptide; D002908:Chronic Disease; D017714:Community-Acquired Infections / Q000097:blood / Q000401:mortality; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D011014:Pneumonia / Q000097:blood / Q000401:mortality; D011379:Prognosis; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000401:mortality; D012372:ROC Curve; D012141:Respiratory Tract Infections / Q000097:blood* / Q000401:mortality; D012720:Severity of Illness Index
D015415:Biomarkers; C000606589:CALCA protein, human; D011498:Protein Precursors; D009320:Atrial Natriuretic Factor; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide