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Master of Public Health

Pneumococcal and Legionella Urinary Antigen Tests in Community-acquired Pneumonia: Prospective Evaluation of Indications for Testing

AUTHORS

Bellew S , Grijalva CG , Williams DJ , Anderson EJ , Wunderink RG , Zhu Y , Waterer GW , Bramley AM , Jain S , Edwards KM , Self WH , . Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2018 9 28; ().

ABSTRACT

Background: Adult community-acquired pneumonia (CAP) guidelines from the Infectious Diseases Society of America (IDSA) and American Thoracic Society (ATS) include indications for urinary antigen tests (UATs) for Streptococcus pneumoniae (SP) and Legionella pneumophila (LP). These recommendations were based on expert opinion and have not been rigorously evaluated.

Methods: We used data from a multicenter prospective surveillance study of adults hospitalized with CAP to evaluate the sensitivity and specificity of the IDSA/ATS UAT indications for identifying patients who test positive. SP and LP UATs were completed on all included patients. Separate analyses were completed for SP and LP using two-by-two contingency tables comparing the IDSA/ATS indications (UAT recommended vs not recommended) and UAT results (positive vs negative). Additionally, logistic regression was used to evaluate the association of each individual criterion in the IDSA/ATS indications with positive UAT results.

Results: Among 1,941 patients, UATs were positive for SP in 81 (4.2%) and LP in 32 (1.6%). IDSA/ATS indications had 61% (95% CI: 49%-71%) sensitivity and 39% (95% CI: 37%-41%) specificity for SP, and 63% (95% CI: 44%-79%) sensitivity and 35% (95% CI: 33%-37%) specificity for LP. No clinical characteristics were strongly associated with positive SP UATs, while features associated with positive LP UATs were hyponatremia, fever, diarrhea, and recent travel.

Conclusions: Recommended indications for SP and LP urinary antigen testing in the IDSA/ATS CAP guidelines have poor sensitivity and specificity for identifying patients with positive tests; future CAP guidelines should consider other strategies for determining which patients should undergo urinary antigen testing.

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