Screening urine with a leukocyte esterase strip and subsequent chlamydial testing of asymptomatic men attending primary care practitioners.

BACKGROUND AND OBJECTIVES: The detection of asymptomatic urethritis using a leukocyte esterase (LE) strip may have a role in primary care screening to select men who need diagnostic testing for Chlamydia trachomatis and Neisseria gonorrhoeae. STUDY
DESIGN: Eight-hundred and eighty-two men, 16 to 35 years of age were studied when they attended their family physician or university health clinic for nongenitourinary complaints. First void urine (FVU) was tested by an LE strip (Chemstrip 2 LN, Boehringer Mannheim Corp., Indianapolis, IN), Chlamydiazyme (Abbott Laboratories, N. Chicago, IL) enzyme immunoassay with confirmatory blocking and polymerase chain reaction (PCR) with chlamydial plasmid primers.
RESULTS: Forty-five men (5.1%) were positive (> trace) by LE strip. Of the LE-positive urines, 9 (20.0%) were positive by EIA or PCR, and none of the LE-negatives were positive by EIA or PCR. Twenty-three LE positives (5 EIA/PCR-positive; 1 PCR-positive; 17 EIA/PCR-negative) were able to be followed with a second urine and 2 urethral swabs. All of the 6 chlamydia-positives who had follow-up tests were positive by both immunoassay and PCR on urine. Based on the FVU results, the prevalence of asymptomatic chlamydial infection was 1.0% (9/88) (95% CL, 0.5 to 1.9) for which the LE urine strip was 100% (9/9) sensitive and 95.9% (837/873) specific. Analyses based on screening 1,000 men, 16 to 25 years of age, showed that the cost per case detected was $192.00 using the LE strip (> 1+) to select urine specimens for EIA testing, compared to $1,326.00 using the EIA to test all urine specimens.
CONCLUSION: In this low prevalence, primary care setting, the LE urine strip was an accurate screening test, which if used to preselect urine specimens for subsequent chlamydial testing, would be less costly per case detected than assaying each specimen for chlamydia.