a unified optimal resource allocation model for screening and treating asymptomatic women for...
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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 KCenters for Disease Control and Prevention
(CDC)
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
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?
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
Clinical Alternatives Considered
1. Screen and treat for CT only2. 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 GC5. Screen for and treat for GC only and
presumptively treat for CT
For each risk-group the following strategies are possible:
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
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
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
Test Positivity Ratesby Clinic Type
Age group(years)
CT(%)
GC(%)
GC with CT (%)
15 – 19 10.6 1.2 46.0
20 – 24 6.9 0.8 39.3
25 2.3 0.4 30.0
Age group(years)
CT(%)
GC(%)
GC with CT (%)
15 – 19 12.5 8.1 45.5
20 – 24 8.0 6.5 32.7
25 3.0 2.0 20.0
STD clinic
Family planning clinic
Variables - TestCT Test Sensitivi
tySpecifici
tyCost
1 Pace CT 0.780 0.780 8.03
2 BDPT-CT 0.993 0.993 9.42
3 Pace 2C 0.928 0.928 5.61
4 BDPT-Dual
0.981 0.981 7.82
GC
1 Culture 0.850 0.995 4.20
2 PCR 0.995 0.990 9.26
3 Pace 2C PCR 0.993 5.61
4 BDPT-Dual 0.900 0.995 7.82BDPT – Becton Dickinson Probe Tec
Variables - Treatment
CT Treatment Effectiveness
Cost
1 Doxycycline 0.900 4.00
2 Azithromycin
0.965 9.50
GC
1 Ceftriaxone 0.977 15.37
2 Ciprofloxacin
0.972 5.27
3 Cefpodoxime
0.965 7.32
Clinical Costs and Outcomes
Other CostsPatient visitPID case
ProbabilitiesReturn rate for treatmentPID in untreated cases 0.21
1,434.00$ 14.00$
0.80
Results
Test Positivity at which Screening is Cost-saving
PID cost(US $)
Pathogen (Test type)
CT(Pace 2)
GC(Culture)
GC(PCR)
1434 5.1% 2.4% 4.9%
1900 3.7% 1.8% 3.6%
4131 1.7% 0.8% 1.6%
Sensitive to PID cost
Results – FP Clinic
Total Program Cost†
Screening Coverage
Test #CuredCost-
saving†
17,437
CT (all)GC (all)
BDPT-Dual
BDPT-Dual
53.3 -1,391
15,635CT (all)GC (all)
BDPT-CTculture
52.6 192
14,214 CT (all)GC ( 24, pres.)
Pace 2CTculture
51.9 1,432
11,458CT (all)GC (none)
BDPT-CT-
49.6 3,483
7,668CT ( 24)GC (pres.)
BDPT-CT-
43.8 5,229‡
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
Results – FP Clinic
Total Program Cost†
Screening Coverage
Test #CuredCost-
saving†
17,437
CT (all)GC (all)
BDPT-Dual
BDPT-Dual
53.3 -1,391
15,635CT (all)GC (all)
BDPT-CTculture
52.6 192
14,214 CT (all)GC ( 24, pres.)
Pace 2CTculture
51.9 1,432
11,458CT (all)GC (none)
BDPT-CT-
49.6 3,483
7,668CT ( 24)GC (pres.)
BDPT-CT-
43.8 5,229‡
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
Results – FP Clinic
Total Program Cost†
Screening Coverage
Test #CuredCost-
saving†
17,437
CT (all)GC (all)
BDPT-Dual
BDPT-Dual
53.3 -1,391
15,635CT (all)GC (all)
BDPT-CTculture
52.6 192
14,214 CT (all)GC ( 24, pres.)
Pace 2CTculture
51.9 1,432
11,458CT (all)GC (none)
BDPT-CT-
49.6 3,483
7,668CT ( 24)GC (pres.)
BDPT-CT-
43.8 5,229‡
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
Results – STD Clinic
Total Program Cost†
Screening Coverage
Test#Cure
dCost-
saving†
18,878
CT (all)GC (all)
BDPT-Dual
BDPT-Dual
97.8 10,578
16,928CT (all)GC (all)
BDPT-Dual
Culture92.8 11,020
12,788
CT ( 20)GC ( 20)
BDPT-Dual
BDPT-Dual
85.4 12,934
12,757CT ( 20, pres.)GC (all)
BDPT-CTCulture 83.0 12,245
8,331CT (all)GC (all)
Pace 2CPace 2C
82.0 15,849‡
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
Results – STD Clinic
Total Program Cost†
Screening Coverage
Test#Cure
dCost-
saving†
18,878
CT (all)GC (all)
BDPT-Dual
BDPT-Dual
97.8 10,578
16,928CT (all)GC (all)
BDPT-Dual
Culture92.8 11,020
12,788
CT ( 20)GC ( 20)
BDPT-Dual
BDPT-Dual
85.4 12,934
12,757CT ( 20, pres.)GC (all)
BDPT-CTCulture 83.0 12,245
8,331CT (all)GC (all)
Pace 2CPace 2C
82.0 15,849‡
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
Results – STD Clinic
Total Program Cost†
Screening Coverage
Test#Cure
dCost-
saving†
18,878
CT (all)GC (all)
BDPT-Dual
BDPT-Dual
97.8 10,578
16,928CT (all)GC (all)
BDPT-Dual
Culture92.8 11,020
12,788
CT ( 20)GC ( 20)
BDPT-Dual
BDPT-Dual
85.4 12,934
12,757CT ( 20, pres.)GC (all)
BDPT-CTCulture 83.0 12,245
8,331CT (all)GC (all)
Pace 2CPace 2C
82.0 15,849‡
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
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
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