THP 14 The New Urethritis Diagnostic Criteria in the 2015 CDC STD Treatment Guidelines: How Much More Does It Buy?

Thursday, September 22, 2016
Galleria Exhibit Hall
Elfriede Agyemang, MD1, Lisa E. Manhart, PhD, MPH2, Matthew R. Golden, MD, MPH3, Julia C. Dombrowski, MD, MPH3 and Lindley A. Barbee, MD, MPH3, 1Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, 2Departments of Epidemiology and Global Health, University of Washington, Seattle, WA, 3HIV/STD Program and Department of Medicine, Public Health - Seattle & King County and University of Washington, Seattle, WA

Background: The diagnostic criterion for gram stain diagnosis of urethritis was lowered from ≥5 polymorphonuclear cells (PMNs) per high power field (HPF) to ≥2PMNs/HPF in the 2015 CDC STD Treatment Guidelines based on data from a single urban sexually transmitted diseases (STD) clinic in Colorado. We sought to 1) quantify the sensitivity, specificity and predictive values of the older criterion (≥5 PMNs/hpf) in our clinic and 2) compare our results with Colorado’s in order to inform our decision to adopt these new guidelines.  

Methods:  We used clinical data of all men who presented to the Public Health- Seattle & King County (PHSKC) STD clinic for evaluation of new urethral symptoms between January 2001 and December 2014 for this analysis. Receipt of antibiotics ≤1 month prior, known exposure to chlamydia or gonorrhea, or a previous positive test were exclusion criteria. Clinicians report urethral gram stain (GS) result as 0-4 PMNs/hpf, 5-9 PMNs/hpf and ≥10 PMNs/hpf.   

Results: 21,925 men presented to the PHSKC STD clinic with urethral symptoms and 19,991 (91%) were included in this analysis. 13,552 had both GS and urethral culture/urine NAAT, of which 14.1% were diagnosed with chlamydia. In our clinic, the old criterion of ≥5 PMNs/hpf had a higher sensitivity, 94.7%, and negative predictive value (NPV), 97.7%, than Colorado’s (sensitivity 83.7%, NPV 91.2%). At PHSKC STD Clinic, 4,636 (23%) gram stains had 0-4 PMNs/hpf; urine NAAT and/or urethral swab culture for chlamydia were obtained from 4,454 (96.1%) of these men, of which 101 (2.3%) were diagnosed with chlamydia infection.  In Colorado, chlamydia was found in 8.8% (472/5359) of GS with 0-4 PMNs/hpf.  

Conclusions: Use of the new urethritis diagnostic criterion in our clinic only identifies a small number of additional urethral chlamydia infections, a finding that appears to differ geographically. Further validation of the new cut-point is merited.