Enhancing STI molecular laboratory diagnosis without increased cost

Background: The CDC and APHL recommend the use of Nucleic Acid Amplification Tests (NAAT) for detecting Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC), and endorsed the concept of pooling specimens as an effective method to reduce costs without compromising test performance. The Oakland County Health Division evaluated and validated the performance of pooling NAAT samples for amplified GC and CT, and subsequently for Trichomonas vaginalis (TV) on a commercial NAAT system. TV infection is prevalent in 10% of our clinic population, causes adverse health consequences during pregnancy and is associated with infertility and increased HIV transmission rates. Method: 592 samples were tested in pools of 2, 3, 4 and 10 samples. The performance of the pooled sample was compared to the performance of the samples tested individually (non-pooled). A cost analysis model determined the savings per pool size. Results: Sensitivity and specificity from non-pooled and pooled samples were comparable. Cost reduction from pooling was 23.8%, 31.2%, 30.9%, and 5.0% for pools of 2, 3, 4, and 10 specimens, respectively. Conclusion: The pooling protocol for screening in a low prevalence population could save more than 50% of the cost per sample. In a high STI prevalence population, a pool of 3 samples saved the most, 31% of the reagent cost of the test, and logistically was easiest to manage. For a laboratory with an annual NAAT reagent cost of $200,000, the cost savings would be $62,000. We used this cost savings to expand the STI Laboratory program by adding TV to our NAAT test. This critical Public Health issue, STI diagnosis, has been expanded and enhanced without increased cost due to this program.