The clinical diagnosis of urethral discharge.

When a standard method for grading urethral discharge that is based on quantity (profuse, moderate, or scant) and quality (purulent, cloudy, or clear) is used, the optimal performance of the clinical diagnosis of gonorrhea is 73%. This performance (true positives over true plus false positives) is dependent not only on the sensitivity, specificity, and prevalence of gonorrhea but also on the components of that prevalence, i.e., the specific mix of patients who attend a clinical service. Optimal performance, as determined through use of a relative operating characteristics curve, will vary from setting to setting depending upon certain patient variables, such as race and sexual preference. Clinics with full diagnostic service would not employ clinical diagnosis as a screening tool directly, but rather as an epidemiologic device for helping to characterize patient populations at risk. Areas with less developed clinic facilities might apply these observations for clinical decision making in the absence of laboratory support.