BACKGROUND: To improve patient care and enhance statewide surveillance efforts, the Utah Department of Health (UDOH) updated our Communicable Disease Rule to require the electronic reporting of negative results. UDOH is only permitted to utilize these results for stated purposes and only collects data associated with specified conditions. Chlamydia (CT) and gonorrhea (GC) were specified effective January 1, 2015. If a negative test result is not appended to an existing case within 18 months, data are de-identified and maintained in a denominator database for disease surveillance efforts.
METHODS: To determine how the collection of negative lab data and the associated percent positivity have changed during 2015-2016, negative lab data from the denominator database and positive lab data from the Utah National Electronic Disease Surveillance System (UT-NEDSS) were combined and total statewide rates were analyzed. Three high volume, high quality ELR feeds from ARUP, LabCorp, and Utah Public Health Laboratory (UPHL) were analyzed separately to assess percent positivity by laboratory. As negative lab results are only reportable by ELR, manually reported positive results were excluded from these analyses. To assess the effect on case management, case data from 2015 were also analyzed to determine the frequency of negative data appendage.
RESULTS: Data from January 2015 to October 2016 were analyzed. In 2016, 8664 negative CT labs were reported a month on average (a 30.1% increase from 2015) and 9150 negative GC labs were reported a month on average (a 27.9% increase from 2015). During 2015-2016, CT positivity decreased from 7.5% to 6.1% and GC positivity remained stable (1.6% to 1.5%). Positivity in the three high-volume labs remained constant throughout the time period; however, differences existed between labs. UPHL reported higher positivity rates for CT and GC, 9.9% and 2.5%, compared to ARUP, 4.1% and 1.0%, and LabCorp, 3.9% and 0.5%. Finally, negative lab data was appended to 10.7% of CT cases and 15.4% of GC cases in 2015.
CONCLUSIONS: As chlamydia and gonorrhea are often asymptomatic, observed case reports are heavily influenced by changes in screening. Reporting negative laboratory results enables state epidemiologists to assess trends in positivity which can help to better explain trends in morbidity. Since not all laboratories report results via ELR, statewide positivity rates may be biased; therefore, analyzing trends by reporting lab is vital. Appending negative data to case reports can improve case management by providing test of cure results.