Performance of urine leukocyte esterase in asymptomatic male youth: another look with nucleic acid amplification testing as the gold standard for Chlamydia detection.
OBJECTIVE
To re-evaluate the sensitivity and specificity of leukocyte esterase (LE) for screening adolescent and young adult males for Chlamydia trachomatis using a nucleic acid amplification test (NAAT) as the gold standard.


METHODS
This study was conducted at two Massachusetts Department of Youth Services sites and one Job Corps site. Recently admitted asymptomatic sexually active male youth aged 14 to 25 years (mean 16.6 years) were recruited between January 2001 and July 2003 (N = 1008). Participants provided first part voided urine specimens for testing with LE and Chlamydia NAAT. The sensitivity, specificity, and positive and negative predictive value of urine LE for identification of Chlamydia infection were determined using NAAT as the gold standard.


RESULTS
Fifty-seven (5.7%) participants were infected with Chlamydia as defined by a positive NAAT. Defining trace + as the LE cut point resulted in sensitivity and specificity of 57.9% and 78.3%, respectively. Defining 1+ as the cut point resulted in sensitivity and specificity of 47.4% and 96.1%, respectively.


CONCLUSIONS
Urine leukocyte esterase is a moderately sensitive method to screen for Chlamydia. Nevertheless, a substantial proportion of infections are not detected with LE screening. When feasible, urine NAAT provides a much more sensitive and equally noninvasive method of detecting Chlamydia. However, if LE is used as an initial screen followed by NAAT confirmation of LE positive samples, we recommend using trace LE as the cut point for positive results.
Blake
Diane R
DR
Department of Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA. diane.blake@umassmed.edu
Lemay
Celeste A
CA
Gaydos
Charlotte A
CA
Quinn
Thomas C
TC
D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D002265:Carboxylic Ester Hydrolases / Q000652:urine*; D002690:Chlamydia Infections / Q000175:diagnosis*; D002692:Chlamydia trachomatis; D006801:Humans; D008297:Male; D021141:Nucleic Acid Amplification Techniques; D011237:Predictive Value of Tests; D012016:Reference Values; D012680:Sensitivity and Specificity; D012725:Sexual Behavior
C021443:leukocyte esterase; D002265:Carboxylic Ester Hydrolases