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The Real World of STD Prevention

Impacts of Sexually Transmitted Disease/HIV Outreach Sites on the Effectiveness of Detecting New Infections in Baltimore City, 2015 to 2018

Nguyen, Minh Phuong MPH; Sembajwe, Sophie MPH∗,†; Rompalo, Anne Marie MD, ScM∗,†,‡; Zenilman, Jonathan Mark MD∗,†,‡

Author Information
Sexually Transmitted Diseases: January 2021 - Volume 48 - Issue 1 - p 1-4
doi: 10.1097/OLQ.0000000000001262
  • Free

Mobile outreach testing has demonstrated effectiveness in identifying new and early sexually transmitted disease (STD)/HIV infections in urban settings among high-risk individuals.1 A prior study indicated that mobile outreach was more successful than clinic-based STD/HIV testing at recruiting population of color, individuals with lower educational attainment, individuals with binge drinking behavior, first-time STD/HIV testers, and substance use individuals.2 Despite the apparent benefits of mobile outreach testing for STD/HIV, limited research on the varying effectiveness in case identification of different types of mobile outreach settings is available. Prior literature has often grouped all settings of mobile outreach testing together to determine effectiveness and feasibility.1,3,4 However, effectiveness may also depend on the variations in settings at which outreach is performed, not only the mode (i.e., mobile vs. fixed) being used.

Better understanding of specific mobile outreach setting types can facilitate outreach planning for health departments and community-based organizations. The data offer an opportunity to compare the varying outputs from the different mobile outreach testing setting types: community centers, community events, drug treatment/mental health centers, schools/colleges, shelters/assistance programs, and street corners. Effectiveness, for this analysis, will be defined as the number and proportion of new syphilis and HIV cases identified at each setting.

MATERIALS AND METHODS

Sexually transmitted disease/HIV community outreach involves STD/HIV education, counseling, and testing in the community, especially in areas with high burden of disease throughout Baltimore City. We have grouped the mobile outreach settings into 6 different setting types: community centers, community events, drug treatment/mental health centers, schools/colleges, shelters/assistance programs, and street corners. Community centers include churches, recreational centers, and senior centers. Community events consist of community-sponsored events, government-sponsored events, festivals, fairs, clubs, and entertainment events. Finally, street corners consist of street-based outreach settings. Outreach sites were chosen based on geospatial analysis of STD/HIV burden in Baltimore City and requests for STD/HIV testing by the community.

All clients who visited any of the outreach sites were administered an intake interview questionnaire before STD/HIV testing. Sexually transmitted disease/HIV mobile van testing at all outreach sites was free of charge, and clients who chose to get STD/HIV tests were provided with small monetary or gift incentives. Intake interviews consisted of demographic, sexual history, and behavioral history questions. Serologic testing was performed to diagnose syphilis and HIV.

Syphilis and HIV are reportable diseases.5 Positive syphilis and HIV laboratory results obtained during the outreach visit were cross-checked with the Maryland Department of Health statewide PRISM sexually transmitted infection surveillance database to determine if an infection of HIV or syphilis was newly or previously diagnosed.

For the syphilis analysis, zip codes were coded into 3 categories of low, moderate, and high based on a separate 2015 Baltimore City Health Department (BCHD) geospatial analysis of early syphilis rates by zip codes.6

The number of cases for each setting type was cross-tabulated, and Pearson χ2 and Fisher exact tests were conducted to assess statistically significant associations (using P values) between new HIV/syphilis diagnoses and setting type. Subsequently, bivariable and multivariable firth logistic regression models for rare events were used to obtain unadjusted and adjusted odds ratios of new syphilis diagnoses for each of the outreach setting types compared with community centers, used as the reference setting type. There were too few new HIV cases to warrant accurate regression analysis; therefore, only syphilis cases were used. Proportion estimates using the Clopper-Pearson exact method were also calculated with 95% confidence intervals and SEs to assess the likelihood of new syphilis and HIV diagnoses in each mobile outreach setting type.

RESULTS

Statistical analyses used cross-sectional retrospective outreach data from July 1, 2015, to June 30, 2018, at 236 mobile van outreach sites. There were 8098 syphilis testing encounters (423 under community centers, 719 under community events, 371 under drug treatment/mental health centers, 250 under schools/colleges, 2379 under shelters/assistance programs, and 3956 under street corners) across 5337 unique clients and 7946 HIV testing encounters (417 under community centers, 725 under community events, 364 under drug treatment/mental health centers, 261 under schools/colleges, 2278 under shelters/assistance programs, and 3901 under street corners) across 5342 unique clients for the period of analysis. Inclusion criteria consisted of all clients who sought syphilis and HIV testing at any of the BCHD 236 mobile outreach sites and were 18 years or older during this period.

For syphilis, across the observed period, the community centers category had an average uptake of 4.8 encounters per event (88 total events), community events had 10.7 encounters per event (67 events), drug treatment/mental health centers had 6.3 encounters per event (59 events), schools/colleges had 7.4 encounters per event (34 events), shelter/assistance programs had 7.3 encounters per event (324 events), and street corners had 7.0 encounters per event (560 events).

For HIV, the community centers category had an average uptake of 4.7 encounters per event (89 total events), community events had 11.0 encounters per event (66 events), drug treatment/mental health centers had 6.3 encounters per event (58 events), schools/colleges had 7.6 encounters per event (35 events), shelter/assistance programs had 7.0 encounters per event (327 events), and street corners had 7.1 encounters per event (552 events).

Study population characteristics for clients tested for syphilis are shown in Table 1. Among clients tested for syphilis, 3177 (59.5%) were male. When demographic characteristics were stratified by testing setting categories, mean age for shelters/assistance programs was the highest, followed by community centers, drug treatment/mental health centers, street corners, community events, and lastly schools/colleges. For race, most clients were Black, ranging from 71.8% to 91.5% at each setting. Most male clients seen for syphilis testing were reported as non–men who have sex with men, ranging from 88.9% to 97.7%. Clients mainly reported being stably housed at the time of the testing encounter, ranging from 64.7% to 88.2%. Of 8098 syphilis testing encounters overall, there were 3828 clients (47%) who were seen for mobile outreach testing only once, whereas all other clients had multiple encounters throughout the 3-year period of analysis, with some clients being encountered as many as 13 times.

TABLE 1 - Characteristics for Syphilis and HIV Mobile Van Testing
Syphilis (n = 5337 Clients) Site Categories
Community Centers (n = 264) Community Events (n = 567) Drug Treatment/Mental Health Centers (n = 232) Schools/Colleges (n = 212) Shelters/Assistance Programs (n = 1273) Street Corners (n = 2789)
Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n)
Age, y 45.0 13.8 36.5 13.8 44.8 11.4 24.9 11.3 48.0 11.5 44.2 13.1
Sex
 Female 47.3 125 52.6 298 42.2 98 59.0 125 28.0 356 41.2 1150
 Male 51.9 137 47.1 267 57.8 134 41.0 87 71.9 915 58.7 1637
 Unknown 0.8 2 0.4 2 0.2 2 0.1 2
Race
 Black/African American 85.6 226 71.8 407 74.6 173 91.5 194 79.3 1009 84.2 2349
 White 6.8 18 18.9 107 24.6 57 2.4 5 17.7 225 12.6 351
 Other 6.4 17 9.2 52 0.7 2 6.1 13 2.6 33 2.9 80
 Unknown 1.1 3 0.2 1 0.5 6 0.3 9
Education level
 HS/GED/equivalent 54.2 143 45.7 259 65.1 151 11.3 24 62.1 790 63.6 1774
 Less than HS 18.6 49 9.2 52 20.7 48 0.5 1 20.5 261 17.2 479
 More than HS 26.9 71 42.9 243 13.8 32 87.3 185 16.3 207 17.1 477
 Unknown 0.4 1 2.3 13 0.4 1 0.9 2 1.2 15 2.1 59
Screening zip code by prevalence
 Low 0.7 4 49.1 114 80.7 171 0.4 11
 Moderate 80.3 212 42.0 238 43.5 101 10.9 23 73.1 930 62.2 1734
 High 19.7 52 57.3 325 7.3 17 8.5 18 26.9 343 37.4 1044
MSM status
 No 97.0 256 88.9 504 97.8 227 96.2 204 96.4 1227 97.7 2726
 Yes 3.0 8 11.1 63 2.2 5 3.8 8 3.6 46 2.3 63
Housing status
 Literally homeless 2.3 6 2.3 13 6.9 16 0.9 2 23.1 294 5.0 140
 Stably housed 86.7 229 88.2 500 76.7 178 64.7 823 82.8 2308
 Unstably housed 0.8 2 0.5 3 1.3 3 86.3 183 2.1 27 1.2 32
 Unknown 10.2 27 9.0 51 15.1 35 12.7 27 10.1 129 11.1 309
HIV (n = 5342 Clients) Community Centers (n = 270) Community Events (n = 577) Drug Treatment/Mental Health Centers (n = 235) Schools/Colleges
(n = 222)
Shelters/Assistance Programs
(n = 1244)
Street Corners
(n = 2794)
Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n) Mean (%) SD (n)
Age, y 44.9 13.8 36.8 13.7 45.0 11.6 24.6 10.8 47.9 11.5 44.0 13.2
Sex
 Female 46.3 125 53.0 306 42.1 99 59.9 133 28.1 349 41.2 1151
 Male 53.0 143 46.6 269 57.9 136 40.1 89 71.9 894 58.7 1641
 Unknown 0.7 2 0.4 2 0.1 1 0.1 2
Race
 Black/African
 American 85.6 231 72.1 416 74.5 175 91.4 203 78.6 978 84.0 2346
 White 7.0 19 19.2 111 24.3 57 2.3 5 18.6 231 12.7 356
 Other 6.3 17 8.5 49 1.3 3 6.3 14 2.4 30 3.0 83
 Unknown 0.7 3 0.2 1 0.4 5 0.3 9
Education level
 HS/GED/equivalent 54.8 148 46.3 267 63.8 150 11.3 25 62.9 782 63.7 1781
 Less than HS 20.0 54 9.0 52 20.9 49 0.5 1 19.6 244 17.0 476
 More than HS 24.8 67 42.1 243 14.9 35 87.4 194 16.4 204 17.3 482
 Unknown 0.4 1 2.6 15 0.4 1 0.9 2 1.1 14 2.0 55
MSM status
 No 96.3 260 89.8 518 98.3 231 96.4 214 97.0 1206 97.9 2736
 Yes 3.7 10 10.2 59 1.7 4 3.6 8 3.0 38 2.1 58
Housing status
 Literally homeless 2.6 7 2.3 13 6.8 16 0.9 2 23.3 290 5.3 147
 Stably housed 86.3 233 87.4 504 77.0 181 86.0 191 64.6 804 82.6 2307
 Unstably housed 0.7 2 0.5 3 0.9 2 2.4 30 1.2 33
 Unknown 10.4 28 9.9 57 15.3 36 13.1 29 9.7 120 11.0 307
GED indicates General Equivalency Diploma; HS, high school.

Study population characteristics for clients tested for HIV are shown in Table 1. Among the mobile outreach clients tested for HIV, there were 3172 (59.4%) men. The mean age of clients was highest at shelters/assistance programs, then drug treatment/mental health centers, community centers, street corners, community events, and schools/colleges. Most clients who were tested for HIV were Black, ranging from 72.1% to 91.4% across outreach setting types. Education-level attainment for clients tested for HIV across mobile outreach category types was similar to that among clients tested for syphilis. Most male clients tested for HIV also reported no MSM status, ranging from 89.8% to 98.3% across setting categories. A majority of clients tested for HIV also reported being stably housed, ranging from 64.6% to 87.4% across outreach setting category. Of the 7946 HIV testing encounters, 3879 clients were seen at mobile outreach once, whereas the remainder of clients were seen multiple times, with some clients with as many as 12 encounters.

Overall, there were a total of 42 new syphilis and 15 new HIV cases identified through BCHD's mobile outreach testing efforts between July 2015 and June 2018.

Of 3956 syphilis testing encounters conducted at street corners, 33 (0.83%) were confirmed new cases. This is the highest proportion of new syphilis cases across the 6 mobile outreach setting categories (Table 2).

TABLE 2 - Syphilis and HIV New Cases
Site Categories No. New Cases Proportion SE Exact (95% CI)
Syphilis
 Community centers (n = 423) 1 0.0024 0.0024 0.00006–0.0131
 Community events (n = 719) 1 0.0014 0.0014 0.00004–0.0077
 Drug treatment/mental health centers (n = 371) 0 0 N/A N/A
 Schools/colleges (n = 250) 0 0 N/A N/A
 Shelters/assistance programs (n = 2,379) 7 0.0029 0.0011 0.00118–0.006058
 Street corners (n = 3956) 33 0.0083 0.0014 0.00575–0.01169
HIV
 Community centers (n = 417) 2 0.0048 0.0034, 0.00058–0.0172172
 Community events (n = 725) 0 0 N/A N/A
 Drug treatment/mental health centers (n = 364) 1 0.0027 0.027 0.000069–0.01521
 Schools/colleges (n = 261) 0 0 N/A N/A
 Shelters/assistance programs (n = 2,278) 4 0.0018 0.0009 0.00048–0.00449
 Street corners (n = 3901) 8 0.0021 0.0007 0.00089–0.004037

Among the HIV cases identified, street corners yielded the largest number of new HIV cases with 8 cases (Table 2). The proportion of new HIV cases was highest among community centers (0.48%).

Correlates of Mobile Outreach Testing Setting Types and New Syphilis Diagnoses

Through multivariable firth logistic regression for rare events, new syphilis case diagnosis was associated with certain mobile van outreach types, although results were not statistically significant (Table 3). Street corners had odds of 2.14 (P = 0.436) of detecting new syphilis infection compared with community centers, after adjusting for sex and race. We were not able to run the firth logistic regression for rare events for HIV, as only 15 new HIV cases were detected during the 3-year period of analysis.

TABLE 3 - Correlates of Outreach Types
Site Categories Unadjusted OR (95% CI) P Adjusted OR (95% CI) P
Community center Reference N/A 1.0 N/A
Community event 0.59 (0.06–5.67) 0.646 0.43 (0.04–4.17) 0.466
Drug treatment center/mental health 0.38 (0.02–9.33) 0.553 0.29 (0.01–7.28) 0.454
School/college 0.56 (0.02–13.85) 0.725 0.58 (0.02–14.21) 0.736
Shelter/assistance program 0.89 (0.13–4.63) 0.898 0.79 (0.13–4.63) 0.793
Street corner 2.40 (0.47–12.39) 0.294 2.14 (0.41–11.12) 0.463

DISCUSSION

We discovered that not all mobile outreach types demonstrated the same effectiveness in detecting new syphilis and HIV cases. For syphilis outreach testing, street corners were the most successful among the 6 mobile outreach setting types at identifying new syphilis, whereas for HIV outreach testing, community centers were the most successful at identifying new cases of HIV. Multivariable firth logistic regression for rare events confirmed further the importance of street corner testing compared with community centers for syphilis; although not statistically significant, clients who were seen at street corner mobile outreach testing settings were more than 2-fold likely than those at community centers to be diagnosed as a new syphilis case after controlling for sex and race.

The small number of new cases limited the power of evaluating the outcome of new syphilis or HIV case finding across the various mobile outreach testing setting categories. Future studies should be conducted to further analyze the ability to identify new syphilis and HIV, especially early syphilis or new HIV seroconversion, as these specific diagnoses are essential triggers for public health actions and can produce the most health impact. Although not statistically significant in this analysis, the findings offer a valuable guide for planning and targeting areas, time, and resources for syphilis and HIV mobile outreach testing in Baltimore City.

Overall, whether because of incentives or easy access, there was a large number of clients who returned to BCHD mobile outreach testing; some clients returned for outreach testing services as many as 13 times. However, when outreach categories were stratified by outreach events, average uptake per event was low. In addition, although street corners and community centers obtained the highest proportions of new syphilis cases, proportions are still quite small. Based on prior studies, greater cost-effectiveness was experienced through testing at clinics in fixed-settings compared with mobile outreach testing models, and rapid testing protocols were shown to be more cost-effective compared with standard blood-based testing protocol.7,8 Although the analysis has limited power, because of the small proportion of newly identified syphilis and HIV cases, the low uptake per outreach event in this analysis, and BCHD's STD/HIV traditional blood-based testing method, the STD/HIV mobile outreach observed during the established period does not seem effective overall. To further assess effectiveness though, additional effectiveness studies should be conducted to look at new STD/HIV among specific high-risk groups.

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