Predictors of a Chlamydia and/or Gonorrhea Infection among Adult Male Emergency Department Patients

Tuesday, March 11, 2008: 4:00 PM
Northwest 2
Roland C Merchant, MD, MPH, ScD , Department of Emergency Medicine, Brown University/Rhode Island Hospital, Providence, RI
Dina M. DePalo , Department of General Internal Medicine, Rhode Island Hospital, Providence, RI
Tao Liu , Warren Alpert Medical School, Brown University, Providence, RI
Josiah D. Rich, MD, MPH , The Center for Prisoner Health and Human Rights, Brown University, Providence, RI
Michael D. Stein, MD , Rhode Island Hospital/Brown University, Providence, RI

Antibiotic resistance, adverse reactions, and costs concerns are driving methods to reduce antibiotic overusage.

We created a clinical prediction rule for chlamydia and/or gonorrhea infections among adult male emergency department (ED) patients to help determine when empiric treatment should be initiated or withheld, pending the results of testing.

Retrospective study of adult male patients at a US ED tested for a possible chlamydia and/or gonorrhea infection from January 1998-December 2004. Statistical models were constructed to create a decision rule to predict either the presence or the absence of a laboratory-confirmed chlamydia and/or gonorrhea infection based upon patient demographic and presenting illness characteristics. Likelihood ratios (LRs) with 95% CIs were calculated. The decision rule was internally validated.

Among 822 patients tested, 29.2% had a 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. The following factors were identified as predictors of a laboratory-confirmed infection for the prediction rule: age 24 years, penile discharge, sexual contact with someone known to have chlamydia and/or gonorrhea, and not having health care insurance. The likelihood of an infection for patients with three or more risk factors was LR 2.70 (1.92-2.79), while the likelihood of no infection for no risk factors was LR 15.6 (3.12-78.30).

Although the prediction rule developed through this study requires prospective, external validation, it appears that using a combination of risk factors revealed through the clinical encounter in the ED can modestly assist ED clinicians in predicting which patients are more likely to have or not have a chlamydia and/or gonorrhea infection

The prediction rule could be used to help decide which patients should receive empiric treatment in the ED or when it could be deferred.