Prevalence of asymptomatic anorectal STI and operating characteristics of screening questions to predict asymptomatic anorectal STI by sub-cohort.

Results expressed in percentage with parenthesis denoting 95 percentage confidence interval for each value.Note: PPV = Positive predictive value. NPV = Negative predictive value. STI = sexually transmitted infection. HRA = High resolution anoscopy. GC = Neisseria gonorrhoeae. CT = Chlamydia trachomatis. DFA = Direct fluorescent antibody assay.NAAT = Nucleic acid amplification test.TP = true positive. FN = false negative. FP = false positive. TN = true negative. n = number.