Wednesday, March 12, 2008
The Centers for Disease Control and Prevention (CDC) recommend rectal Chlamydia (CT) and gonorrhea (GC) screening for men who report receptive anal sex. Inadequate staffing at STD/HIV screening sites may limit compliance with rectal screening recommendations.
To compare results of self-collected versus provider-collected rectal specimens for GCCT nucleic acid amplification testing (NAAT).
MSM who reported receptive anal sex were offered rectal GC/CT screening at a sexual health clinic. 220 paired provider-collected and self-collected rectal specimens were obtained between August and October 2007. A validated NAAT assay was used to test specimens. The results were recorded and analyzed using SAS v.9.0. We calculated the percent agreement and Kappa statistic to measure the pair-wise concordance of provider-collected and self-collected results. Improper samples were excluded from the final analysis. To assess sensitivity we used the composite reference as the standard.
Of the 220 paired specimens collected, 2 GC/CT provider samples and 1 self-collected CT specimen were deemed indeterminate by the lab. The overall prevalence of rectal CT was 18% (40/217); rectal GC was 19% (42/218). Percent agreement for detection of rectal CT and GC was 97% and 95%, respectively. Rectal CT was found in 37 of the paired specimens; 39 from the self-collected and 40 from the provider-collected specimens. Rectal GC was found in 34 of the paired specimens; 42 from the self-collected and 37 from the provider-collected specimens. Kappa coefficient and 95% confidence limits (CL) for rectal CT and GC were 0.92 (95% CL: 0.86, 0.99) and 0.83 (95% CL: 0.73, 0.93), respectively. Self-collected rectal CT and GC sensitivity were 0.93. Provider-collected CT and GC sensitivity were 0.95 and 0.82, respectively.
Self-collected rectal swabs performed as well as provider-collected rectal swabs.
The self collection-method is a feasible alternative in understaffed settings to increase screening.