Abstract
We used an electronic medical records system retrospectively to evaluate how frequently, in a public hospital and its clinics, combined gonorrhea/chlamydia tests were accompanied by a syphilis test before and during a syphilis outbreak. Among 70 330 gonorrhea/chlamydia tests (1996–2000), the proportion with a syphilis test increased from 13% (preoutbreak) to 50% (intervention period) for men and from 6% to 13% for nonpregnant women. The increased syphilis testing coincided with a multifaceted public health intervention.
In 1998, as the Centers for Disease Control and Prevention called for eliminating syphilis from the United States,1 an outbreak was beginning in Indianapolis, Ind (Marion County). The reported annual case rate in the county peaked in 1999 at 50 per 100 000,2 whereas the national rate was 2.5 per 100 000.3
Because symptoms can be minimal or absent in the early stages of syphilis, screening is central to elimination efforts; inadequate screening has been implicated in syphilis outbreaks.4–6 In response to the Indianapolis outbreak, the Marion County Health Department and the community implemented a multifaceted program, designed primarily to increase early case detection. Some interventions involved encouraging clinicians who suspected other sexually transmitted diseases (STDs) to test for syphilis also.
We report a longitudinal, descriptive analysis of syphilis tests performed in association with gonorrhea/chlamydia tests before and during the public health response in Indianapolis.
METHODS
Public Health Interventions (1999–2000)
A letter reporting that a syphilis outbreak was in progress was sent to each primary care physician in Marion County (March 1, 1999). A community-based coalition was organized. Media coverage; presentations at major hospitals; and focused efforts at high-prevalence clinics, homeless shelters, substance abuse treatment centers, and hospital emergency departments were key components. At Wishard Hospital, the county’s public hospital and a major source of cases, computerized feedback to promote syphilis testing was implemented in the emergency department (September 1999); for patients who resided in a high-prevalence zip code, who had a history of injection drug abuse, or who had an STD or STD symptom entered on the current problem list, the electronic discharge orders system displayed a message asking physicians to consider ordering a syphilis test.
A Marion County Health Department analysis found that many patients with syphilis also had a history of other STDs; one of Marion County Health Department’s recommendations, posted in the Wishard Hospital emergency department and mailed to clinicians of selected specialties (June 1999; July 2000), was that clinicians screen for syphilis when they suspected other STDs.
Syphilis Test Data
We studied Wishard Hospital and its neighborhood clinics. Electronic data were extracted from the Regenstrief Medical Records System.7 We identified all occurrences of combined gonorrhea/chlamydia tests (the tests used to screen for gonorrhea/chlamydia) between January 1, 1996, and November 22, 2000. We then determined the proportion of these tests in which the patient also had a syphilis test within 7 days. Pregnant women and patients younger than 12 years were excluded. Occurrences, not results, of the tests were analyzed. The data were categorized into the preoutbreak period (January 1, 1996, to March 31, 1998), the preintervention outbreak period (April 1, 1998, to February 28, 1999), and the intervention period (March 1, 1999, to November 22, 2000). Syphilis testing was analyzed by clinic location, clinician specialty, and patient race and zip code.
Analyses were performed with SAS, Version 8.1 (SAS Institute Inc, Cary, NC), and SPSS, Version 10.0 (SPSS Inc, Chicago, Ill). Units of analysis were gonorrhea/chlamydia testing encounters. Because the electronic data represent a complete listing of encounters, no variation due to sampling occurred; thus, formal statistical testing was not conducted.
RESULTS
We identified 70 330 gonorrhea/chlamydia testing encounters (38 579 patients; mean age at testing = 29 years; 93% women).
The proportion of gonorrhea/chlamydia testing encounters accompanied by a syphilis test increased over time. The trends differed by gender (Figure 1 ▶). From the preoutbreak to the intervention period, the syphilis test rate (proportion of gonorrhea/chlamydia testing encounters with a syphilis test within 7 days) increased among women from 6% to 13% and among men from 13% to 50%. Test rates in Hispanic, African American, and White men increased to 58%, 53%, and 40%, respectively (Table 1 ▶). During the intervention period, test rates were highest in urgent visit locations (men, 64%; women, 15%).
FIGURE 1—
Proportion of gonorrhea/chlamydia tests that were accompanied by a syphilis test.
Note. The data are for encounters (January 1, 1996, to November 22, 2000) at a large, urban, public hospital in Marion County, Ind, and are divided by calendar quarter and by patients’ gender (pregnant women are excluded). The vertical dotted lines divide the study into the preoutbreak period (January 1, 1996, to March 31, 1998), the preintervention outbreak period (April 1, 1998, to February 28, 1999), and the intervention period (March 1, 1999, to November 22, 2000).
TABLE 1—
Proportion (%) of Gonorrhea/Chlamydia Tests With an Accompanying Syphilis Test, by Patient or Clinic Characteristics, Period, and Patients’ Gendera
| Preoutbreak Period | Preintervention Outbreak Period | Intervention Period | ||||
| Women | Men | Women | Men | Women | Men | |
| Patients’ race | ||||||
| Black | 1032/16 234 (6%) | 198/1486 (13%) | 486/6851 (7%) | 69/641 (11%) | 2067/15 364 (13%) | 744/1401 (53%) |
| White | 530/9407 (6%) | 50/373 (13%) | 326/3711 (9%) | 21/190 (11%) | 1114/8325 (13%) | 159/400 (40%) |
| Hispanic | 30/593 (5%) | 8/62 (13%) | 30/488 (6%) | 4/43 (9%) | 155/1735 (9%) | 80/137 (58%) |
| Other | 40/555 (7%) | 4/39 (10%) | 27/289 (9%) | 2/17 (12%) | 74/545 (14%) | 24/52 (46%) |
| Missing | 34/490 (7%) | 6/61 (10%) | 28/285 (10%) | 3/24 (13%) | 65/484 (13%) | 9/48 (19%) |
| Clinic location | ||||||
| Emergency department/urgent visit | 515/8582 (6%) | 170/1315 (13%) | 285/3727 (8%) | 33/503 (7%) | 1258/8325 (15%) | 682/1060 (64%) |
| Hospital clinic | 540/11 916 (5%) | 29/213 (14%) | 228/4572 (5%) | 26/137 (19%) | 775/8934 (9%) | 112/282 (40%) |
| Neighborhood clinic | 395/4283 (9%) | 41/236 (17%) | 302/2450 (12%) | 27/153 (18%) | 1110/7218 (15%) | 77/287 (27%) |
| Other or missing | 216/2499 (9%) | 26/257 (10%) | 82/875 (9%) | 12/123 (10%) | 332/1977 (17%) | 145/410 (35%) |
| Clinician specialty | ||||||
| Internal medicine | 168/4145 (4%) | 151/1181 (13%) | 113/1950 (6%) | 43/524 (8%) | 572/4333 (13%) | 572/1072 (53%) |
| Obstetrics/gynecology | 1217/18 942 (6%) | . . . | 666/8021 (8%) | . . . | 2308/17 943 (13%) | . . . |
| Adolescent medicine | 6/122 (5%) | 14/47 (30%) | 16/212 (8%) | 24/72 (33%) | 59/567 (10%) | 47/137 (34%) |
| Pediatrics | 21/164 (13%) | 9/49 (18%) | 10/91 (11%) | 5/41 (12%) | 24/283 (8%) | 34/97 (35%) |
| Other or missing | 254/3907 (7%) | 92/731 (13%) | 92/1350 (7%) | 27/275 (10%) | 512/3327 (15%) | 360/719 (50%) |
| Area of residence | ||||||
| High-prevalence zip code | 476/7163 (7%) | 91/641 (14%) | 221/2961 (7%) | 28/279 (10%) | 943/6453 (15%) | 318/610 (52%) |
| Any other or missing zip code | 1190/20 116 (6%) | 175/1380 (13%) | 676/8663 (8%) | 71/636 (11%) | 2532/20 000 (13%) | 698/1428 (49%) |
aPregnant women were excluded.
DISCUSSION
This study of 70 330 gonorrhea/chlamydia testing encounters in a public hospital and its clinics showed that syphilis testing increased during a public health campaign to control a syphilis outbreak. Whether the interventions caused the increase in testing and whether screening for syphilis when testing for other STDs was an effective strategy cannot be answered by this study; additional studies are under way.
Syphilis testing increased most dramatically in men, although they accounted for few of the study encounters. Because chlamydia screening is routine in women,8,9 our inclusion criterion—gonorrhea/chlamydia testing—probably identified many asymptomatic women. In contrast, many of the men tested for gonorrhea/chlamydia likely had specific STD symptoms.10 Such symptoms in men may have prompted clinicians to screen them for syphilis. Although the gender differences observed in syphilis testing might have resulted from baseline differences in symptoms, our syphilis testing rates among patients evaluated for gonorrhea/chlamydia are consistent with reports that among those treated for other STDs, men more often than women also were tested for syphilis.11,12
The higher intervention period testing rate among African American and Hispanic men is only partially explained by local epidemiology. Although the outbreak disproportionately affected heterosexual African Americans, Hispanic men, whose infection rate was not disproportionate, also were tested more frequently.
The largest increase in syphilis testing occurred in urgent visit locations. Other STD studies have suggested that emergency department encounters might represent the only opportunity to diagnose syphilis in some persons at high risk.13,14
Acknowledgments
This project was supported in part by the Mid-America Adolescent Sexually Transmitted Disease Clinical Research Center, funded by National Institutes of Health grant AI3924.
We thank Dr Virginia Caine, director of Marion County Health Department, and the Stamp Out Syphilis (SOS) Coalition for their vision and dedication during the outbreak; we also acknowledge the Centers for Disease Control and Prevention and the Indiana State Department of Health for providing collaborative support and funding (CDC Syphilis Elimination Demonstration Site and High Morbidity Area grants) for public health interventions in Marion County.
We gratefully acknowledge Kathleen Irwin, MD, MPH, Charles Akers, PhD, Marilyn F. Graham, PhD, MD, and Donald P. Orr, MD, for their careful review of and thoughtful comments on an earlier version of the brief.
Human Participant Protection The institutional review board of Indiana University–Purdue University at Indianapolis approved the study.
Contributors M. B. Rosenman and S. K. Kraft led the analysis team. J. Harezlak, B. E. Mahon, and B. P. Katz analyzed the data and helped write the brief. J. Harezlak also programmed the data management software. J. Wang extracted the data from the electronic medical records system and assisted with the analyses of the data. J. N. Arno conceived the study and supervised the analyses and the writing of the brief. All authors helped to conceptualize ideas, interpret findings, and review drafts of the brief.
Peer Reviewed
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