Frequency and Characteristics of Biological False-Positive Test Results for Syphilis Reported in Florida and New York City, USA, 2013 to 2017.

Discordant syphilis test results, with a reactive nontreponemal test and nonreactive treponemal test are usually considered biological false-positive test results (BFPs), which can be attributed to other conditions. Syphilis surveillance laws mandate laboratory reporting of reactive syphilis tests, which include many BFPs. We describe the frequency of BFPs, titer distributions, and titer increases from reported test results in Florida and New York City (NYC). Reactive nontreponemal tests for individuals with at least one nonreactive treponemal test and no reactive treponemal test were extracted from sexually transmitted disease (STD) surveillance systems in Florida and NYC from 2013 to 2017. Characteristics of individuals with BFPs were analyzed after selecting the observation with the highest titer from each individual. We next considered all results from individuals to characterize persons who had a 4-fold titer increase between successive nontreponemal tests. Among 526,540 reactive nontreponemal tests, there were 57,580 BFPs (11%) from 39,920 individuals. Over 90% (n = 52,330) of BFPs were low titer (≤1:4), but 654 (1%) were high-titer BFPs (≥1:32). Very high-titer (≥1:128) BFPs were more common among individuals over 60 years of age (odds ratio [OR], 2.68; 95% confidence interval [CI], 1.22 to 5.91). A 4-fold increase in titer was observed among 1,863 (14%) individuals with more than one reported BFP. Most BFPs detected by surveillance were low titer, but some were high titer and some had a 4-fold increase in titer. Review of patient histories might identify underlying conditions contributing to these high and rising titers.

Using an Email Alert to Improve Identification of Pregnancy Status for Women With Syphilis-Florida, 2017-2018.

BACKGROUND: Congenital syphilis can be prevented if syphilis is treated early in pregnancy. Identifying women with syphilis who are pregnant facilitates prioritization for follow-up. In 2016, Florida reported 1062 female syphilis cases, aged 15 to 44 years, and 160 (15%) cases were missing pregnancy status. The Florida Department of Health developed a system-generated weekly email notification sent to local program staff for all female syphilis investigations with unknown pregnancy status. We describe the outcome of these efforts to reduce unknown pregnancy status among women with syphilis. METHODS: Review of the frequency and outcomes (reduction in investigations flagged and change in pregnancy status variable) of the first email notification (October 2, 2017) were compared with subsequent notifications through June 25, 2018. In addition, we reviewed pregnancy status of reported female syphilis cases (age, 15-44 years) from 2013 to 2018. RESULTS: The first email notification listed 76 investigations with unknown pregnancy status. This number decreased to 40 in 1 week and to 22 by 1 month. The decreased volume continued through June 2018 (n = 13). Of the original 76 investigations, 3 women were pregnant, and 38 (50%) were determined to meet the syphilis case definition (including 1 who was pregnant). In 2017, pregnancy ascertainment for female syphilis cases reached 98%. CONCLUSIONS: Focused efforts using email notification to obtain pregnancy status improved ascertainment in large sexually transmitted disease (STD) programs with minimal effort. Most but not all women with unknown pregnancy status were identified as not pregnant.

Going Off Grid: Modeling an Automated Record Search to Process Electronically Reported Reactive Nontreponemal Syphilis Tests.

BACKGROUND: Before searching prior records, sexually transmitted disease programs use syphilis reactor grids to exclude some reactive nontreponemal test results (RNTs) based on patient age, gender, and test titer. We propose a new algorithm that starts with comparing RNTs to previous syphilis nontreponemal tests and current treponemal test results. METHODS: Deduplicated RNTs from Florida's surveillance system (2006-2015) were extracted and stratified on morbidity. An algorithm was developed to triage RNTs. Sensitivity and specificity of the algorithm and the current reactor grid were estimated using reported syphilis cases. A random sample of cases missed by the proposed algorithm, stratified by stage of disease, was reviewed to verify case classification. RESULTS: Reported RNTs increased 58% from 2006 (n = 34,808) to 2015 (n = 55,001) (total = 372,902). The current reactor grid removed 91,518 (24.5%) RNTs and missed 1149 potential cases. Strictly following the reactor grid would result in a sensitivity of 97.4% and a specificity of 27.5%. The proposed algorithm would remove 242,078 (64.9%) RNTs and miss 2768 potential cases. This results in a slightly lower sensitivity of 93.8%, but nearly triples the specificity, 72.9%. A review of a random sample of the 2768 cases estimated that 72.7% would not have met the syphilis surveillance case definition, resulting in an adjusted sensitivity of 98.4%. CONCLUSIONS: In Florida, an algorithm that starts by searching previous syphilis test results vastly improved specificity and slightly improved sensitivity compared with the current reactor grid. Implementing an automated algorithm could increase case ascertainment efficiency and further prioritize likely cases for investigation.