title: Developing a system to predict laboratory-confirmed chlamydial and/or gonococcal urethritis in adult male emergency department patients.
abstract: OBJECTIVE
  We aimed to create a system for predicting which male emergency department (ED) patients with suspected chlamydial and/or gonococcal urethritis would have laboratory-confirmed infections based on clinical factors available at the initial ED encounter.
  
  
  METHODS
  We used statistical models to develop a system to predict either the presence or absence of laboratory-confirmed chlamydial and/or gonorrheal urethritis based on patient demographics and presenting symptoms. Data for the system were extracted from a retrospective chart review of adult male patients who were suspected of having, and were tested for, chlamydial and/or gonococcal urethritis at an adult, urban, northeastern United States, academic ED from January 1998 to December 2004.
  
  
  RESULTS
  Among the 822 patients tested, 29.2% had chlamydia, gonorrhea, or both infections; 13.8% were infected with chlamydia alone, 12.1% were infected with gonorrhea alone, and 3.3% were infected with both. From the statistical models, the following factors were predictive of a positive laboratory test for chlamydia and/or gonorrhea: age < or = 24 years, penile discharge, sexual contact with someone known to have chlamydia and/or gonorrhea, and not having health care insurance. A system using a hierarchical grouping of these factors based on the predicted probabilities of a laboratory-confirmed chlamydial and/or gonococcal urethritis, paired with baseline ED prevalence of these infections, was confirmed through internal validation testing to modestly predict which patients had or did not have a laboratory-confirmed infection.
  
  
  CONCLUSIONS
  This system of a combination of risk factors available during the clinical encounter in the ED modestly predicts which adult male patients suspected of having chlamydial and/or gonorrheal urethritis are more likely to have or not have a laboratory-confirmed infection. A prospective study is needed to create and validate a clinical prediction rule based on the results of this system.
authors.affiliation: Department of Emergency Medicine, Rhode Island Hospital, 593 Eddy St., Providence, RI 02903, USA. rmerchant@lifespan.org
authors.forename: Roland C
authors.initials: RC
authors.lastname: Merchant
authors.forename: Dina M
authors.initials: DM
authors.lastname: DePalo
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Josiah D
authors.initials: JD
authors.lastname: Rich
authors.forename: Michael D
authors.initials: MD
authors.lastname: Stein
mesh_terms: D000293:Adolescent; D000328:Adult; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D016001:Confidence Intervals; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006069:Gonorrhea / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010865:Pilot Projects; D015995:Prevalence; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States; D014526:Urethritis / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D055815:Young Adult