Sensitivity, Specificity, and Positivity Predictors of the Pneumococcal Urinary Antigen Test in Community-Acquired Pneumonia.
BACKGROUND
Detection of the C-polysaccharide of Streptococcus pneumoniae in urine by an immune-chromatographic test is increasingly used to evaluate patients with community-acquired pneumonia.


OBJECTIVE
We assessed the sensitivity and specificity of this test in the largest series of cases to date and used logistic regression models to determine predictors of positivity in patients hospitalized with community-acquired pneumonia.


METHODS
We performed a multicenter, prospective, observational study of 4,374 patients hospitalized with community-acquired pneumonia.


RESULTS
The urinary antigen test was done in 3,874 cases. Pneumococcal infection was diagnosed in 916 cases (21%); 653 (71%) of these cases were diagnosed exclusively by the urinary antigen test. Sensitivity and specificity were 60 and 99.7%, respectively. Predictors of urinary antigen positivity were female sex; heart rate≥125 bpm, systolic blood pressure<90 mm Hg, and SaO2<90%; absence of antibiotic treatment; pleuritic chest pain; chills; pleural effusion; and blood urea nitrogen≥30 mg/dl. With at least six of all these predictors present, the probability of positivity was 52%. With only one factor present, the probability was only 12%.


CONCLUSIONS
The urinary antigen test is a method with good sensitivity and excellent specificity in diagnosing pneumococcal pneumonia, and its use greatly increased the recognition of community-acquired pneumonia due to S. pneumoniae. With a specificity of 99.7%, this test could be used to direct simplified antibiotic therapy, thereby avoiding excess costs and risk for bacterial resistance that result from broad-spectrum antibiotics. We also identified predictors of positivity that could increase suspicion for pneumococcal infection or avoid the unnecessary use of this test.
1 Servicio de Neumología, Hospital Universitario Central Asturias, Oviedo, Spain.
Luis
L
Molinos
2 Servicio de Neumología, Hospital de Cruces, Baracaldo (Bizkaia), Spain.
Rafael
R
Zalacain
3 Servicio de Neumología, ISS/Hospital Universitario La Fe, Valencia, CIBERES, Spain.
Rosario
R
Menéndez
3 Servicio de Neumología, ISS/Hospital Universitario La Fe, Valencia, CIBERES, Spain.
Soledad
S
Reyes
4 Servicio de Neumología, Hospital de Galdakao (Bizkaia), Spain.
Alberto
A
Capelastegui
5 Servei de Pneumologia, Institut Clinic del Torax, IDIBAPS, Universitat de Barcelona, CIBERES, GRS, Spain; and.
Catia
C
Cillóniz
6 Servicio de Neumología, Hospital de la Princesa, Madrid, Spain.
Olga
O
Rajas
7 Servicio de Neumología, Hospital San Jorge, Huesca, Spain.
Luis
L
Borderías
8 Servicio de Neumología, Hospital Carlos Haya, Malaga, Spain.
Juan J
JJ
Martín-Villasclaras
9 Servicio de Neumología, Hospital Miguel Servet, Zaragoza, Spain.
Salvador
S
Bello
10 Servicio de Neumología, Hospital de Valme, Sevilla, Spain.
Inmaculada
I
Alfageme
11 Servicio de Neumología, Hospital Dr. Negrín, Las Palmas de Gran Canaria, Spain.
Felipe
F
Rodríguez de Castro
12 Critical Care, Hospital Vall d'Hebron, Institut de Recerca Vall d'Hebron-UAB, CIBERES, Spain.
Jordi
J
Rello
13 Servicio de Neumología, Hospital Germans Trias i Pujol, Badalona, Spain.
Juan
J
Ruiz-Manzano
5 Servei de Pneumologia, Institut Clinic del Torax, IDIBAPS, Universitat de Barcelona, CIBERES, GRS, Spain; and.
Albert
A
Gabarrús
14 Infectious Disease Section, Medical Care Line, Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas.
Daniel M
DM
Musher
5 Servei de Pneumologia, Institut Clinic del Torax, IDIBAPS, Universitat de Barcelona, CIBERES, GRS, Spain; and.
Antoni
A
Torres
D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D017714:Community-Acquired Infections; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011008:Pneumococcal Infections / Q000652:urine*; D011018:Pneumonia, Pneumococcal / Q000188:drug therapy* / Q000652:urine*; D011135:Polysaccharides, Bacterial / Q000652:urine*; D011379:Prognosis; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae
D000900:Anti-Bacterial Agents; D011135:Polysaccharides, Bacterial
community-acquired pneumonia; pneumococcal urinary antigen; positive predictor factors; sensitivity; specificity