APPENDIX 25
Streptococcus, Group B
DISEASE BURDEN
Epidemiology
For the purposes of the calculations in this report, the committee estimated that there are approximately 7,000 new infections with streptococcus, group B (GBS) and 430 deaths in infants and 4,000 new GBS infections (and no deaths) in pregnant women each year. It is also assumed that there are approximately 11,000 new GBS infections and 2,300 deaths in nonpregnant adults. The highest incidence of disease in nonpregnant adults is in people 65 years of age and older. See Table A25–1.
Disease Scenarios
For the purposes of the calculations in this report, the committee assumed that 90% of GBS disease in neonates is early-onset disease and 20% is late-onset disease. Disease associated with neonatal GBS infections includes bacteremia (86%) and meningitis (14%). Approximately 72% of neonatal GBS infections are early-onset bacteremia, 14% are late-onset bacteremia, 8% are early-onset meningitis, and 6% are late-onset meningitis.
For the purposes of the calculations in the report, the committee assumed that all pregnant women infected with GBS experience chorioamnionitis, endometritis, or bacteremia. These infections are assumed to be associated with 7 days at an HUI of .68. It was assumed that all nonpregnant adults infected
Table A25–1 Incidence of Group B Streptococcus Infection in Noninfants and Nonpregnant Women
Age Groups |
Population |
Incidence Rates (per 100,000) |
Cases |
<1 |
3,963,000 |
0.00 |
0 |
1–4 |
16,219,000 |
0.92 |
149 |
5–14 |
38,056,000 |
0.91 |
347 |
15–24 |
36,263,000 |
1.70 |
616 |
25–34 |
41,670,000 |
1.76 |
731 |
35–44 |
42,149,000 |
1.68 |
708 |
45–54 |
30,224,000 |
4.84 |
1,464 |
55–64 |
21,241,000 |
8.31 |
1,766 |
65–74 |
18,964,000 |
11.57 |
2,194 |
75–84 |
11,088,000 |
22.69 |
2,516 |
85+ |
3,598,000 |
22.70 |
817 |
Total |
263,435,000 |
4.29 |
11,308 |
with GBS experience invasive disease (e.g., bacteremia, sepsis, soft tissue infections) associated with 19 days at an HUI of .66. See Table A25–2.
COST INCURRED BY DISEASE
Table A25–3 summarizes the health care costs incurred by GBS infections. For the purposes of the calculations in this report, it was assumed that GBS infections in pregnant women are associated with additional hospitalization at the time of delivery and associated inpatient and outpatient physician visits and medication. Costs are also included for screening for GBS and chemoprophylaxis of pregnant women. It was estimated that all nonpregnant adults with invasive GBS disease require hospitalization (including inpatient physician visits) and outpatient services as well.
For the calculation in this report, it was assumed that all infants with GBS require hospitalization, including multiple inpatient physician visits and diagnostics. It was assumed that a small percentage of infants with GBS meningitis will require long-term care for 10 years until death.
VACCINE DEVELOPMENT
The committee assumed that it will take 7 years until licensure of a GBS vaccine and that $300 million needs to be invested for approval for use in nonpregnant people, and an additional $100 million needs to be invested for that same vaccine to be used in pregnant women. Special considerations regarding
Table 25–2 Disease Scenarios for Group B Streptococcus Infection in Infants and Adults
|
% of Cases |
Committee HUI Values |
Duration (years) |
INFANTS |
|
||
Bacteremia—NICU |
36.0% |
0.24 |
0.027 (10 days) |
Bacteremia—Non-NICU |
36.0% |
0.24 |
0.027 (10 days) |
Meningitis |
6.4% |
0.27 |
0.047 (17 days) |
Meningitis with impairment |
1.1% |
|
|
acute care (50% NICU; 50% Level 2) |
|
0.27 |
0.047 (17 days) |
permanent impairment—normal lifespan |
|
0.53 |
26.804 (discounted quality adjusted life expectancy at birth) |
Meningitis with early death |
0.5% |
|
|
acute care |
|
0.27 |
0.047 (17 days) |
permanent impairment |
|
0.53 |
10.000 (10 years) |
death by age 10 |
|
0.00 |
25.690 (discounted quality adjusted life expectancy at age 10) |
LATE ONSET DISEASE—20% of infant cases |
|||
Bacteremia |
14.0% |
0.69 |
0.027 (10 days) |
Meningitis |
4.8% |
0.27 |
0.047 (17 days) |
Meningitis with impairment |
0.8% |
|
|
acute care |
|
0.27 |
0.047 (17 days) |
permanent impairment—normal lifespan |
|
0.53 |
26.804 (discounted quality adjusted life expectancy at birth) |
Meningitis with early death |
0.4% |
|
|
acute care |
|
0.27 |
0.047 (17 days) |
permanent impairment |
|
0.53 |
10.000 (10 years) |
death by age 10 |
|
0.00 |
25.690 (discounted quality adjusted life expectancy at age 10) |
ADULTS |
|
||
Maternal Infection |
100% |
|
|
inpatient |
|
0.68 |
0.0192 (7 days) |
outpatient treatment |
|
0.0137 (5 days) |
|
NONPREGNANT ADULTS |
|
||
Invasive disease |
100.0% |
|
|
soft tissue, bone infection; bacteremia; urosepsis; pneumonia |
|
0.66 |
0.052 (19 days) |
Table 25–3 Health Care Costs Associated with GBS Disease in Infants and Adults
|
% with Care |
Cost per Unit |
Units per Case |
Form of Treatment |
INFANTS |
|
|||
EARLY ONSET DISEASE—80% of infant cases |
||||
Bacteremia—NICU |
|
|||
bacteremia, sepsis, pneumonia |
100% |
$12,000 |
1.0 |
hospitalization NICU |
|
100% |
$150 |
10.0 |
physician c |
100% |
$500 |
1.0 |
diagnostic c |
|
Bacteremia—Level 2 care |
|
|||
bacteremia, sepsis, pneumonia |
100% |
$7,000 |
1.0 |
hospitalization non-NICU |
|
100% |
$150 |
10.0 |
physician c |
100% |
$500 |
1.0 |
diagnostic c |
|
Meningitis |
|
|||
acute care |
50% |
$12,000 |
1.0 |
hospitalization NICU |
|
50% |
$7,000 |
1.0 |
hospitalization |
100% |
$150 |
17.0 |
physician c |
|
100% |
$500 |
1.0 |
diagnostic c |
|
Meningitis with impairment |
|
|||
acute care |
50% |
$12,000 |
1.0 |
hospitalization NICU |
|
50% |
$7,000 |
1.0 |
hospitalization |
100% |
$150 |
17.0 |
physician c |
|
100% |
$500 |
1.0 |
diagnostic c |
|
permanent impair-ment normal lifespan* |
100% |
$225 |
365.0 |
long-term care*/per year |
Meningitis with early death |
|
|||
acute care |
50% |
$12,000 |
1.0 |
hospitalization NICU |
|
50% |
$7,000 |
1.0 |
hospitalization |
100% |
$150 |
17.0 |
physician c |
|
100% |
$500 |
1.0 |
diagnostic c |
|
permanent impair-ment for 10-year period** |
100% |
$225 |
365.0 |
long-term care*/per year |
LATE ONSET DISEASE—20% of infant cases |
||||
Bacteremia |
|
|||
bacteremia, sepsis, pneumonia |
100% |
$7,000 |
1.0 |
hospitalization |
|
100% |
$150 |
10.0 |
physician c |
100% |
$500 |
1.0 |
diagnostic c |
|
Meningitis |
|
|||
acute care |
50% |
$12,000 |
1.0 |
hospitalization NICU |
|
50% |
$7,000 |
1.0 |
hospitalization |
100% |
$150 |
17.0 |
physician c |
|
100% |
$500 |
1.0 |
diagnostic c |
|
Meningitis with impairment |
|
|||
acute care |
50% |
$1,200 |
1.0 |
hospitalization NICU |
|
50% |
$7,000 |
1.0 |
hospitalization |
100% |
$150 |
10.0 |
physician c |
|
% with Care |
Cost per Unit |
Units per Case |
Form of Treatment |
|
100% |
$500 |
1.0 |
diagnostic c |
permanent impairment normal lifespan* |
100% |
$225 |
365.0 |
long-term care*/per year |
Meningitis with early death |
|
|||
acute care |
50% |
$12,000 |
1.0 |
hospitalization NICU |
|
50% |
$7,000 |
1.0 |
hospitalization NICU |
50% |
$150 |
10.0 |
physician c |
|
50% |
$500 |
1.0 |
diagnostic c |
|
permanent impairment for 10-year period** |
100% |
$225 |
365.0 |
long-term care*/per year |
PREGNANT WOMEN |
|
|||
Maternal Infection (chorioamnionitis, endometritis, bacteremia) |
||||
additional inpatient treatment at time of delivery |
100% |
$1,000 |
1.0 |
hospitalization (in addition to normal delivery) |
|
100% |
$150 |
1.0 |
physician c |
100% |
$50 |
1.0 |
medication b |
|
outpatient treatment |
100% |
$100 |
1.0 |
physician b |
screening |
90% |
$50 |
1.0 |
diagnostic a |
intrapartum chemoprophylaxis |
25% |
$50 |
1.0 |
medication b |
NONPREGNANT ADULTS |
|
|||
Invasive disease |
|
|||
soft tissue, bone infection bacteremia; urosepsis; pneumonia |
100% |
$4,000 |
1.0 |
hospitalization |
|
100% |
$150 |
19.0 |
physician c |
100% |
$500 |
1.0 |
diagnostic c |
|
outpatient |
100% |
$100 |
2.0 |
physician b |
NOTE: *long-term care—$225/day is maintenance expenditure per resident for residential facilities for persons with mental retardation. **cost per case is calculated as “present value” of annual cost for remaining life time (life expectancy at birth or 10 years, depending on scenario); additional discounting for immunization interval |
development of a vaccine for use in pregnant women is discussed within the body of the report. Table 4–1 summarizes vaccine development assumptions for all vaccines considered in this report.
VACCINE PROGRAM CONSIDERATIONS
Target Population
The results of two vaccine strategies will be described. Both strategies involve annual immunization of 2,600,000 high-risk, nonpregnant adults (65 years of age or with specific chronic diseases). Both strategies involve immunization of younger females. One strategy involves annual immunization of pregnant women (approximately 1,630 primiparas). The other strategy involves annual immunization of 1,840,000 12-year-old girls. For the purposes of the calculations in this report, it is assumed that 30% of high-risk adults, 50% of 12-year-old girls, will utilize the vaccine. Additionally, it was assumed that utilization of the vaccine by pregnant women will either be 10% or 90%.
Vaccine Schedule, Efficacy, and Costs
For the purposes of the calculations in this report, it was estimated that this vaccine would cost $50 per dose and that administration costs would be $10 per dose. Default assumptions of a 3-dose series and 75% effectiveness were accepted. Table 4–1 summarizes vaccine program assumptions for all vaccines considered in this report.
RESULTS
Immunization of Pregnant Women and At-Risk Adults
If a vaccine program for group B streptococci were implemented today and the vaccine were 100% efficacious and utilized by 100% of the target population, the annualized present value of the QALYs gained would be 37,400. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the QALYs gained would be 10,200 for 90% utilization by pregnant women and 4,500 for 10% utilization by pregnant women.
If a vaccine program for group B streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the health care costs saved would be $630 million. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the health care costs saved would be $310 million for 90% utilization by pregnant women and $45 million for 10% utilization by pregnant women.
If a vaccine program for group B streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population,
the annualized present value of the program cost would be $760 million. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the program cost would be $285 million for 90% utilization by pregnant women and $120 million for 10% utilization by pregnant women.
Using committee assumptions of time and costs until licensure, the fixed cost of vaccine development has been amortized and is $12 million for a group B streptococci vaccine.
If a vaccine program were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the cost per QALY gained is $3,400. Using committee assumptions of less-than-ideal utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the cost per QALY gained is -$1,500 for 90% utilization by pregnant women and $20,000 for 10% utilization by pregnant women. A negative value represents a saving in costs in addition to a saving in QALYs.
See Chapters 4 and 5 for details on the methods and assumptions used by the committee for the results reported.
Immunization of Girls at Puberty and At-Risk Adults
If a vaccine program for group B streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the QALYs gained would be 33,000. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the QALYs gained would be 6,200.
If a vaccine program for group B streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the health care costs saved would be $435 million. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the health care costs saved would be $125 million.
If a vaccine program for group B streptococci were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the program cost would be $800 million. Using committee assumptions of less-than-ideal efficacy and utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the program cost would be $215 million.
Using committee assumptions of time and costs until licensure, the fixed cost of vaccine development has been amortized and is $9 million for a group B streptococci vaccine.
If a vaccine program were implemented today and the vaccine was 100% efficacious and utilized by 100% of the target population, the annualized present value of the cost per QALY gained is $11,000. Using committee assumptions of less-than-ideal utilization and including time and monetary costs until a vaccine program is implemented, the annualized present value of the cost per QALY gained is $16,000.
See Chapters 4 and 5 for details on the methods and assumptions used by the committee for the results reported.
READING LIST
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