Effect of Specimen Order on Chlamydia trachomatis and Neisseria gonorrhoeae Test Performance and Adequacy of Papanicolaou Smear

Ghanem, Khalil G.; Koumans, Emilia H.; Johnson, Robert E.; Sawyer, Mary K.; Papp, John R.; Unger, Elizabeth R.; Black, Carolyn M.; Markowitz, Lauri E.

doi:10.1016/j.jpag.2005.11.002

« Previous Next »Journal of Pediatric and Adolescent Gynecology
Volume 19, Issue 1 , Pages 23-30, February 2006

Effect of Specimen Order on Chlamydia trachomatis and Neisseria gonorrhoeae Test Performance and Adequacy of Papanicolaou Smear

Khalil G. Ghanem, MD
- Johns Hopkins University School of Medicine, Baltimore, Maryland
- Address correspondence to: Khalil G. Ghanem, Johns Hopkins Bayview Medical Center 4940 Eastern Avenue, B3 North, Baltimore, MD 21224
Emilia H. Koumans, MD, MPH
- Centers for Disease Control and Prevention, Atlanta, Georgia
Robert E. Johnson, MD
- Centers for Disease Control and Prevention, Atlanta, Georgia
Mary K. Sawyer, MD
- Emory University School of Medicine, Atlanta, Georgia, USA
John R. Papp, PhD
- Centers for Disease Control and Prevention, Atlanta, Georgia
Elizabeth R. Unger, PhD, MD
- Centers for Disease Control and Prevention, Atlanta, Georgia
Carolyn M. Black, PhD
- Centers for Disease Control and Prevention, Atlanta, Georgia
Lauri E. Markowitz, MD
- Centers for Disease Control and Prevention, Atlanta, Georgia

Abstract

Study Objective

To evaluate the effect of specimen collection order on the performance of diagnostic tests for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC), and the specimen adequacy of ThinPrep Papanicolaou (Pap) smears.

Design

Prospective cohort study.

Setting

Public adolescent clinic.

Population

313 women.

Interventions

The order of five cervical testing specimens was randomized for (1) ligase chain reaction (LCR) and (2) polymerase chain reaction (PCR) for both CT and GC; (3) transcription-mediated amplification (TMA) for CT; (4) culture for CT; and (5) cytology and LCR for GC and CT performed on ThinPrep Pap specimens. For CT and GC, a reference standard was based on three different tests performed on separate specimens. Generalized estimating equations were used to account for repeated measures.

Main Outcome Measure

Sensitivity and specificity of diagnostic tests.

Results

The proportion of inadequate Pap smears was independent of specimen order. As a group, nucleic acid amplification test (NAAT) sensitivity and specificity for GC and CT were similar in the first two (early) and last three (late) swabs. Although point estimates for sensitivity were higher in the early swabs compared to the late swabs for GC LCR (13% difference), GC PCR (13%), and CT TMA (10%), these differences were not statistically significant. Their clinical significance warrants further investigation.

Conclusions

In clinical settings where both Pap smears and STI testing are performed in adolescents, clinical considerations can influence the order of specimen collection, since neither Pap specimen adequacy nor test performance of NAAT for CT and GC were significantly associated with swab order.

Key Words: Papanicolaou smear, Neisseria gonorrhoeae, Chlamydia trachomatis, Swab order, Diagnostic testing, Nucleic acid amplification tests