1. A Unified Optimal Resource Allocation Model for Screening and Treating Asymptomatic Women for Chlamydia Trachomatis and Neisseria Gonorrhoeae Abban B, Tao G, Gift T, Irwin K Centers for Disease Control and Prevention (CDC)

2. Background Up to 70% CT and up to 50% GC infections are asymptomatic CT infection among GC infected populations can be as high 50% Different segments of the population have different prevalences of CT, GC, and co- infection; range of disparities is wide Availability of different testing technologies at varying cost and performance Many clinics operate under fixed budgets and cannot accommodate universal screening

3. Study Objective Determines the optimal combination of screening coverage, test selection and treatment for CT and GC in asymptomatic women; specifically  At what prevalence is it cost-saving to screen a population for CT or GC?  Is it more beneficial to screen with more sensitive but more expensive tests?  Is presumptive treatment cost-saving?

4. What test(s) should be used? Which risk-group(s) should be screened for CT, or GC, or both? Should patient be dual-treated? What treatment(s) should be used? Clinical Management Decision

5. Clinical Alternatives Considered 1. Screen and treat for CT only 2. Screen and treat for GC only 3. Screen and treat for both CT and GC 4. Screen and treat for CT only and presumptively treat for GC 5. Screen for and treat for GC only and presumptively treat for CT For each risk-group the following strategies are possible:

6. Methods The optimal strategy was defined as one that maximized  the number of women cured or  the cost-saving value (cost of averted PID minus screening and treatment costs for CT and/or GC) Selective screening based on readily ascertained risk-factor: Age 4 tests each for CT and GC, including dual test(s) 2 treatment regimens for CT and 3 for GC A mixed integer optimization model for a hypothetical cohort of 1000 asymptomatic women

7. Model Assumptions All women who visited the clinic lacked symptoms of CT and GC infections A strategy could allow the screening of selected age groups or all patients Return rate for treatment was assumed to be the same for all age groups Test and treatment for each infection were the same all age groups

8. Variables CT and GC positivity by age group Co-infection rates by age group Tests sensitivity, specificity and cost Treatments effectiveness and cost All parameter values were from published literature

9. Test Positivity Rates by Clinic Type Age group (years) CT (%) GC (%) GC with CT (%) 15 – 1910.61.246.0 20 – 246.90.839.3  25 2.30.430.0 Age group (years) CT (%) GC (%) GC with CT (%) 15 – 1912.58.145.5 20 – 248.06.532.7  25 3.02.020.0  STD clinic  Family planning clinic

10. Variables - Test CTTestSensitivitySpecificityCost 1Pace CT 0.780 8.03 2BDPT-CT 0.993 9.42 3Pace 2C 0.928 5.61 4BDPT-Dual 0.981 7.82 GC 1 Culture0.8500.9954.20 2 PCR0.9950.9909.26 3 Pace 2CPCR0.9935.61 4 BDPT-Dual0.9000.9957.82 BDPT – Becton Dickinson Probe Tec

11. Variables - Treatment CTTreatmentEffectivenessCost 1Doxycycline0.9004.00 2Azithromycin0.9659.50 GC 1Ceftriaxone0.97715.37 2Ciprofloxacin0.9725.27 3Cefpodoxime0.9657.32

12. Clinical Costs and Outcomes

13. Results

14. Test Positivity at which Screening is Cost-saving PID cost (US $) Pathogen (Test type) CT (Pace 2) GC (Culture) GC (PCR) 14345.1%2.4%4.9% 19003.7%1.8%3.6% 41311.7%0.8%1.6% Sensitive to PID cost

15. Results – FP Clinic Total Program Cost † Screening Coverage Test#Cured Cost- saving † 17,437 CT (all) GC (all)BDPT-Dual 53.3-1,391 15,635 CT (all) GC (all) BDPT-CT culture 52.6192 14,214 CT (all) GC (  24, pres. ) Pace 2CT culture 51.91,432 11,458 CT (all) GC (none) BDPT-CT - 49.63,483 7,668 CT (  24) GC (pres.) BDPT-CT - 43.85,229 ‡ CT (2.3 - 10.6%), GC (0.4 - 1.2%), GC with CT (30.0 - 46.0%) † All costs in US dollars (2003)|BDPT – Becton Dickinson Probe Tec ‡ Optimal cost-saving strategy|pres. – presumptively treat

16. Results – FP Clinic Total Program Cost † Screening Coverage Test#Cured Cost- saving † 17,437 CT (all) GC (all)BDPT-Dual 53.3-1,391 15,635 CT (all) GC (all) BDPT-CT culture 52.6192 14,214 CT (all) GC (  24, pres. ) Pace 2CT culture 51.91,432 11,458 CT (all) GC (none) BDPT-CT - 49.63,483 7,668 CT (  24) GC (pres.) BDPT-CT - 43.85,229 ‡ CT (2.3 - 10.6%), GC (0.4 - 1.2%), GC with CT (30.0 - 46.0%) † All costs in US dollars (2003)|BDPT – Becton Dickinson Probe Tec ‡ Optimal cost-saving strategy|pres. – presumptively treat

17. Results – FP Clinic Total Program Cost † Screening Coverage Test#Cured Cost- saving † 17,437 CT (all) GC (all)BDPT-Dual 53.3-1,391 15,635 CT (all) GC (all) BDPT-CT culture 52.6192 14,214 CT (all) GC (  24, pres. ) Pace 2CT culture 51.91,432 11,458 CT (all) GC (none) BDPT-CT - 49.63,483 7,668 CT (  24) GC (pres.) BDPT-CT - 43.85,229 ‡ CT (2.3 - 10.6%), GC (0.4 - 1.2%), GC with CT (30.0 - 46.0%) † All costs in US dollars (2003)|BDPT – Becton Dickinson Probe Tec ‡ Optimal cost-saving strategy|pres. – presumptively treat

18. Results – STD Clinic Total Program Cost † Screening Coverage Test#Cured Cost- saving † 18,878 CT (all) GC (all)BDPT-Dual 97.810,578 16,928 CT (all) GC (all) BDPT-Dual Culture 92.811,020 12,788 CT (  20) GC (  20)BDPT-Dual 85.412,934 12,757 CT (  20, pres.) GC (all) BDPT-CT Culture 83.012,245 8,331 CT (all) GC (all)Pace 2C 82.015,849 ‡ CT (3.0 – 12.5%), GC (2.0 – 8.1%), GC with CT (20.0 – 45.5%) † All costs in US dollars (2003)|BDPT – Becton Dickinson Probe Tec ‡ Optimal cost-saving strategy|pres. – presumptively treat

19. Results – STD Clinic Total Program Cost † Screening Coverage Test#Cured Cost- saving † 18,878 CT (all) GC (all)BDPT-Dual 97.810,578 16,928 CT (all) GC (all) BDPT-Dual Culture 92.811,020 12,788 CT (  20) GC (  20)BDPT-Dual 85.412,934 12,757 CT (  20, pres.) GC (all) BDPT-CT Culture 83.012,245 8,331 CT (all) GC (all)Pace 2C 82.015,849 ‡ CT (3.0 – 12.5%), GC (2.0 – 8.1%), GC with CT (20.0 – 45.5%) † All costs in US dollars (2003)|BDPT – Becton Dickinson Probe Tec ‡ Optimal cost-saving strategy|pres. – presumptively treat

20. Results – STD Clinic Total Program Cost † Screening Coverage Test#Cured Cost- saving † 18,878 CT (all) GC (all)BDPT-Dual 97.810,578 16,928 CT (all) GC (all) BDPT-Dual Culture 92.811,020 12,788 CT (  20) GC (  20)BDPT-Dual 85.412,934 12,757 CT (  20, pres.) GC (all) BDPT-CT Culture 83.012,245 8,331 CT (all) GC (all)Pace 2C 82.015,849 ‡ CT (3.0 – 12.5%), GC (2.0 – 8.1%), GC with CT (20.0 – 45.5%) † All costs in US dollars (2003)|BDPT – Becton Dickinson Probe Tec ‡ Optimal cost-saving strategy|pres. – presumptively treat

21. Limitations The alternative of screening and treating for CT and screening CT-positives for GC was not considered Published range of values for direct cost attributable to PID is wide: (1,433 – 5,000) Repeat infections were not considered CT and GC positivity in asymptomatic STD clinic patients may be less than the reported population-wide rates

22. Conclusions Optimal control strategy varies with CT and GC positivity, CT-GC co-infection rates, total program budget, test costs and PID cost Influence of treatment cost on overall program cost is minimal A switch from one test to another may not yield significant change in the number of women cured The optimal strategy from a cost-saving perspective and from a number-of-cures perspective may vary The model provides a flexible tool to analyze different scenarios when identifying a control strategy for CT, GC, or both