1. It's not what you know, but who you know: Risk factors for re-infection in the Philadelphia High School STD Screening Program
Jennifer Beck, MPH
APHA Annual Meeting
November 5, 2007

2. Outline Scope of the Problem: (Chlamydia) CT and (Gonorrhea) GC
Philadelphia High School STD Screening Program (PHSSSP) Introduction
Research Design and Methods
Results and Discussion
Conclusions and Recommendations

3. Study Objective
Identify and analyze risk factors associated with CT or GC re-infection within the same school year among high school students screened by the Philadelphia Department of Public Health (PDPH) STD Control Program

4. Scope of the Problem Source: PDPH 2007
C. trachomatis 976,445 cases in
N. gonorrhoeae 300,000+ reported each year 7
CT and GC infections are largely asymptomatic
Medical Outcomes include: pelvic inflammatory disease (PID), ectopic pregnancy, and other pregnancy related complications in females and infertility in both males and females 21
Source: PDPH 2007

5. Adolescent Re-infection Risk
35%-60% of re-infection occurs within the first four months
Re-infection rates are highest in adolescent females and CT rates can range between 20% - 58%
Researchers speculate why these rates are so high in this population
Anatomy
Immaturity (behavioral)
Risky behavior
(Schillinger et al, 2003; Niccolai et al, 2007 )
Why rates are so high:
anatomical differences that increase susceptibility – and part of the risky behavior is lack of power (or perceived lack of power) to negotiate safe sex with partners.

6. Introduction to PHSSSP
Philadelphia High School STD Screening Program (PHSSSP)
Began in school year to address high rates of GC and CT among adolescents.
Educational session followed by voluntary screening
PHSSSP consists of an educational session and a CT and GC screening
The educational sessions covers basic information about STDs, consequences of untreated STDs and how they are acquired
Students voluntarily screen and all information is confidential
Urine specimens are collected from students who wish to be screened – NAAT screening of urine

7. Introduction to PHSSSP, Con.
In the second year of PHSSSP:
Re-screening program initiated: Active follow-up for students with an initial positive test 3-6 months after treatment to detect re-infections in the same school year
Disease Intervention Specialist (DIS) partner follow-up initiated: DIS interview those who are treated in the school or in the STD clinic to elicit the names and locating information of sex partners for follow-up

8. PHSSSP – The First 4 Years
Table 1. Summary of the first 4 years
No. of Students
School Year
Screened
69,035
Positive
3308 (4.80%)
Treated
3289 (99.4%)
For the following analyses, year 1 data was excluded because no partner treatment, no retesting, no interviews

9. Research Methods and Design
All secondary data from PHSSSP
Microsoft Access 2003 and SAS version 9.1 were used
Univariate analyses and multi-variable analyses
P-value of ≤ 0.05 as a significant value
95% Confidence Limits

10. Total included with a retest by eligibility
948 (42.8%) Tested after March 1st
1269 (57.2%) Eligible for Retest
2217 (93.5%) Initial Positives
645 (50.8%) Not Located for Retest
624 (59.2%) Valid Retests
49 (7.90%) Retests without interviews
575 (25.9%) Retests included
Inclusion factors:
Aged 12 – 20 years old
Attended one of the schools included in the PHSSSP
Lived within Philadelphia limits
Had a positive urine screen for CT and/or GC
Had an interview file from their initial positive screening
School years: (“Year 2”), (“Year 3”), and (“Year 4”)
Had a to have retested in the same school year of the initial positive test with PHSSSP
Verification of treatment for initial positive
Eligible for a retest (tested prior to March 1st of the school year)
Present in school the day PDPH staff returned for the retest in order to provide urine specimen

11. Candidate Risk Factors
Gender
Self-reported race/ethnicity
Dual infection at first test
Partner(s) treatment status
School year
School type
Grade
Age at initial test (continuous)
Age group (categorical)
Time to retest
Residential ZIP code reported incidence

12. Main Study Variable: Partners’ Treatment Status
Table 2. Variable Categories
Did students with an initial positive screen name partners?
Were these partners treated by PDPH?
Group # No
N/A 1
Yes
Yes, all were treated
Yes, but only some were treated
No, none were treated 2
The variable Partner(s) treatment status consisted of 4 possibilities categorized in 2 groups:

13. Results ~ 49,322 students were screened in years 2,3, and 4
2269 (4.6%) students with an initial positive test
52 exclusions
624 Retests
575 met inclusion criteria (49 missing interview files)
The re-infection rate within the same school year was 13.6% (78 out of 575)

14. Results, Con. Risk of re-infection: Positive retests by gender and partner(s) treatment status
* This group includes at least some or all partners treated and no partners named
Figure 3.
*having untreated named partners is strongly associated with increased risk in females but not males.

15. Table 3. Retest positives by gender and partner(s) treatment status
Results
Table 3. Retest positives by gender and partner(s) treatment status
Female
RR (95% C.L.)
Male
RR (95% C.L)
Other
1.00 (ref)
1.08 (0.638, 1.83)
None treated
2.20 (1.32, 3.65)
1.31 (0.355, 4.83)
*Other includes at least some or all partners treated and no partners named

16. Conclusions and Recommendations
Naming sexual partners and having them treated by the PDPH is key to reducing re-infection rates among the students in PHSSSP, especially among females
Males are most likely infecting females and should be retested as well.
Recommendations include adding an educational component on re-infection to the existing educational presentation

17. Acknowledgements
Philadelphia Department of Public Health, Division of Disease Control, STD Control
Vic Spain, DVM, PhD
Melinda E. Salmon
Greta Anschuetz, MPH
Martin Goldberg

18. Contact Information
Phone:
For more information about the PHSSSP contact Melinda Salmon:
Phone: