Systematic review and metaanalysis: urinary antigen tests for Legionellosis.
BACKGROUND
Urinary antigen assays offer simplicity and rapidity in diagnosing Legionnaires' disease, though studies report a range of sensitivities. We conducted a systematic review to assess the test characteristics of Legionella urinary antigen.


METHODS
We searched Medline, Excerpta Medica Database, and bibliographies of retrieved articles. English-language studies were used and included if the absolute number of true-positive, false-negative, true-negative, and false-positive observations were available, and the "gold standards" were described clearly. Two investigators independently reviewed articles and extracted data. Quality was assessed with the Quality Assessment for Diagnostic Accuracy Studies (QUADAS). Sensitivities and specificities were pooled using a random-effects model weighted with the inverse of the SE calculated through the Wald method.


RESULTS
Fifty articles were retrieved for detailed evaluation, and 30 met the inclusion criteria. All but two studies focused on serotype 1 Legionella. Forty assays were reported using six different methodologies, whereas 26 assays used commercial tests, and 14 assays used in-house tests. Study quality was generally low, with average QUADAS scores of 4.4 of a total of 14 points (range, 1 to 9 points). The pooled sensitivity was 0.74 (95% CI, 0.68 to 0.81), and the specificity was 0.991 (95% CI, 0.984 to 0.997). Higher quality studies had lower sensitivity, and there was evidence of publication bias.


CONCLUSIONS
Legionella urinary antigen for serotype 1 appears to have excellent specificity, though modest sensitivity. However, the poor quality of the included studies and the presence of publication bias suggest an overestimation of test performance. High-quality studies are needed.
Shimada
Toshihiko
T
Department of Epidemiology and Healthcare Research, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan; Department of General Internal Medicine, Rakuwakai Otowa Hospital, Kyoto, Japan. Electronic address: smdtshk@gmail.com.
Noguchi
Yoshinori
Y
Department of General Internal Medicine, Nagoya Daini Red Cross Hospital, Nagoya, Japan.
Jackson
Jeffrey L
JL
Uniformed Services University, Bethesda MD.
Miyashita
Jun
J
Department of Epidemiology and Healthcare Research, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan; Department of General Internal Medicine, Rakuwakai Otowa Hospital, Kyoto, Japan.
Hayashino
Yasuaki
Y
Department of Epidemiology and Healthcare Research, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan.
Kamiya
Toru
T
Department of General Internal Medicine, Rakuwakai Otowa Hospital, Kyoto, Japan.
Yamazaki
Shin
S
Department of Epidemiology and Healthcare Research, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan.
Matsumura
Tadashi
T
Department of General Internal Medicine, Rakuwakai Otowa Hospital, Kyoto, Japan.
Fukuhara
Shunichi
S
Department of Epidemiology and Healthcare Research, Graduate School of Medicine and Public Health, Kyoto University, Kyoto, Japan.