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APPENDIX 17
Neisseria gonorrhea
DISEASE BURDEN
Epidemiology
For the purposes of the calculations in this report, the committee estimated that there are 1 million new cases of gonorrhea infection each year in the United States. Slightly more than half of these occur in males. It was assumed that 90% of cases occur in people between 15 and 34 years of age. Mortality was presumed to be minimal; 5 deaths were included for women per year (consequences of serious sequelae, for example). See Table A17–1 for a summary of the age distribution of gonorrhea infections.
Disease Scenarios
For the purposes of the calculation in this report, the committee assumed that 50% of cases in women are asymptomatic, but that half of those cases are detected through screening programs and receive treatment. The other 50% of cases experience mild manifestations, such as cervicitis, urethritis, or endometritis. More serious acute health consequences associated with gonorrhea infections in women include pelvic inflammatory disease (PID), salpingitis, and perihepatitis. Consequences of PID are assumed to occur with a 5-year lag from infection and include ectopic pregnancy, chronic pelvic pain, and infertility. The health utility index and length of time spent in the health state range from .85 HUI for 7 days (cervicitis) to .46 HUI for 2 days (surgery for PID) to .6 HUI for more than 20 years (chronic pelvic pain).
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Table A17–1 Incidence of N.gonorrhea Infection in Women and Men
Age Groups
Female Population
Incidence Rates (per 100,000)
% Distribution of Cases
Cases
<1
1,933,000
0.00
0.0000
0
1–4
7,905,000
29.10
0.0050
2,300
5–14
18,554,000
111.57
0.0450
20,700
15–24
17,747,000
1,555.19
0.6000
276,000
25–34
20,835,000
662.35
0.3000
138,000
35–44
21,238,000
75.81
0.0350
16,100
45–54
15,447,000
29.78
0.0100
4,600
55–64
11,140,000
20.65
0.0050
2,300
65–74
10,544,000
0.00
0.0000
0
75–84
6,814,000
0.00
0.0000
0
85+
2,593,000
0.00
0.0000
0
Total
134,750,000
341.37
1.0000
460,000
Age Groups
Male Population
Incidence Rates (per 100,000)
% Distribution of Cases
Cases
<1
2,030,000
0.00
0.0000
0
1–4
8,314,000
32.48
0.0050
2,700
5–14
19,502,000
124.60
0.0450
24,300
15–24
18,516,000
1,749.84
0.6000
324,000
25–34
20,835,000
777.54
0.3000
162,000
35–44
20,911,000
90.38
0.0350
18,900
45–54
14,777,000
36.54
0.0100
5,400
55–64
10,101,000
26.73
0.0050
2,700
65–74
8,420,000
0.00
0.0000
0
75–84
4,274,000
0.00
0.0000
0
85+
1,005,000
0.00
0.0000
0
Total
128,685,000
419.63
1.0000
540,000
For the purposes of the calculations in this report, the committee assumed that 15% of cases in men are asymptomatic and untreated. The overwhelming utility index and length of time spent in the health state range from .85 HUI for 7 days (cervicitis) to .46 HUI for 2 days (surgery for PID) to .6 HUI for more than 20 years (chronic pelvic pain).
For the purposes of the calculations in this report, the committee assumed that 15% of cases in men are asymptomatic and untreated. The overwhelming proportion of symptomatic cases involve urethritis, which was assumed to be associated with an HUI of .84 and 7 days duration. A small percentage of men infected with gonorrhea experience epididymitis. The HUI and length of time spent in the health state for these manifestations range from .84 HUI for 7 days (urethritis) to .3 HUI for 3 days (hospitalization for epididymitis).
A small fraction of both men and women infected with gonorrhea experience disseminated infections. Hospitalization for these patients is associated with an HUI of .52 for 4 days; outpatient treatment is associated with a week of a higher HUI state. See Table A17–2 for a summary of the disease states associated with gonorrhea infections.
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Table A17–2 Disease Scenarios for N.Gonorrhea Infection in Women and Men
% of Cases
Committee HUI Values
Duration (years)
WOMEN
Total Cases
460,000
Asymptomatic
50.0%
1.00
untreated
25.0%
treated (detected in screening, etc.)
25.0%
Mild (cervicitis, urethritis, endometritis, bartholinitis)
50.0%
outpatient
0.85
0.0192 (7 days)
Serious (PID, salpingitis, perihepatitis) —outpatient only
10.0%
0.63
0.0274 (10 days)
Serious (PID, salpingitis, perihepatitis) —inpatient
inpatient—no surgery
7.5%
0.57
0.0110 (4 days)
inpatient with surgery
2.5%
0.46
0.0055 (2 days)
outpatient after inpatient
10.0%
0.83
0.0274 (10 days)
Serious (PID, etc.)
0.8%
inpatient with bilateral salpingo-oophorectomy
0.40
0.0027 (1 day)
outpatient after inpatient
0.76
0.0274 (10 days)
infertility
0.82
23.6523 (remaining lifetime at onset)
ALL PID sequelae: 5-year lag from infection
Ectopic Pregnancy—Outpatient only
3.3%
0.58
0.0767 (4 weeks)
Ectopic Pregnancy—Inpatient
3.3%
inpatient
0.23
0.0082 (3 days)
outpatient after inpatient
0.66
0.0767 (4 weeks)
Chronic pelvic pain
6.6%
0.60
22.7313 (remaining lifetime at onset+5 years)
discounted quality adjusted life expectancy at age 28.7
Infertility
4.0%
0.82
22.7313 (remaining lifetime at onset+5 years); discounted quality adjusted life expectancy at age 28.7
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —outpatient only
0.5%
0.60
0.0219 (8 days)
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% of Cases
Committee HUI Values
Duration (years)
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —inpatient
0.5%
inpatient
0.52
0.0110 (4 days)
outpatient after inpatient
0.78
0.0192 (7 days)
MEN
Total cases
540,000
Asymptomatic
15.0%
1.00
Urethritis
84.0%
0.84
0.0192 (7 days)
Epididymitis—outpatient
0.9%
0.46
0.0192 (7 days)
Epididymitis—inpatient
0.1%
0.30
0.0082 (3 days)
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —outpatient
0.5%
0.60
0.0219 (8 days)
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —inpatient
0.5%
inpatient
0.52
0.0110 (4 days)
outpatient after inpatient
0.78
0.0192 (7 days)
COST INCURRED BY DISEASE
Table A17–3 summarizes the health care costs incurred by gonorrhea infections. For the purposes of the calculations in this report, it was assumed that for mild acute manifestations in both men and women (e.g., cervicitis and urethritis), health care costs include a limited visit with a physician and inexpensive diagnostics and medications.
Disseminated gonococcal infections in both women and men were assumed to be associated with inpatient costs (hospitalization, diagnostics, specialist physicians) and outpatient costs (similar to that required for inpatient treatment but slightly fewer physician visits).
Outpatient treatment in women of more serious manifestations include increased diagnostic costs above those for cervicitis. Inpatient treatment (e.g., for PID or salpingitis) includes hospitalization costs, physician services (including surgeons and anesthesiologists for those who require surgery) and diagnostics. Outpatient costs following hospitalization include follow-up care with a specialist. Half of the cases of ectopic pregnancy were assumed to be treated as inpatient and half as outpatient. Costs include hospital costs (more for inpatient), specialist physicians, surgeons and anesthesiologists, and diagnostics. A followup visit with a specialist was also included. Chronic pelvic pain was associated with numerous physician visits, diagnostics, and medication. 75% of women with chronic pelvic pain were presumed to undergo outpatient laparoscopy, and
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Table A17–3 Health Care Costs Associated with N.gonorrhea Infection in Women and Men
% with Care
Cost per Unit
Units per Case
Form of Treatment
WOMEN
Asymptomatic
untreated
treated (detected in screening, etc.)
100%
$50
1
physician a
100%
$50
1
diagnostic a
100%
$50
1
medication b
Mild (cervicitis, urethritis, endometritis, bartholinitis)
outpatient
100%
$50
1
physician a
100%
$50
1
diagnostic a
100%
$50
1
medication b
Serious (PID, salpingitis, perihepatitis)
outpatient
100%
$50
1
physician a
100%
$100
1
diagnostic b
100%
$100
1
medication
Serious (PID, salpingitis, perihepatitis)
inpatient—no surgery
100%
$4,000
1
hospitalization
100%
$150
3
physician c
100%
$100
1
diagnostic b
Serious (PID, salpingitis, perihepatitis)
inpatient with surgery
100%
$4,000
1
hospitalization
100%
$150
3
physician c
100%
$500
4
surgical staff
100%
$100
1
diagnostic b
Serious (PID, salpingitis, perihepatitis)
outpatient after inpatient
100%
$100
1
physician b
Serious (PID, etc.)
inpatient and outpatient
100%
$1,550
1
outpatient laparoscopy
ALL PID sequelae: 5-year lag from infection
Ectopic Pregnancy—Outpatient
PID sequela: 5-year lag
outpatient only
100%
$1,000
1
laparoscopy
100%
$500
1
surgical staff
100%
$500
1
surgical staff
100%
$50
1
diagnostic a
100%
$100
1
physician b
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% with Care
Cost per Unit
Units per Case
Form of Treatment
Ectopic Pregnancy—Inpatient
PID sequela: 5-year lag
inpatient
100%
$4,000
1
hospitalization
100%
$150
3
physician c
100%
$100
1
diagnostic b
100%
$500
2
surgical staff
outpatient after inpatient
100%
$100
1
physician b
Chronic pelvic pain
PID sequela: 5-year lag
treatment assumed to occur 5 years after onset of infection
100%
$100
1
physician b
duration of condition: remaining lifetime
100%
$50
4
physician a
100%
$50
1
medication b
100%
$100
1
diagnostic b
outpatient laparoscopy
75%
$1,000
1
hospitalization
75%
$500
1
surgical staff
75%
$500
1
surgical staff
lower abdominal surgery
30%
$4,000
1
hospitalization
30%
$500
1
surgical staff
30%
$500
1
surgical staff
30%
$150
3
physician c
Infertility
PID sequela: 5-year lag
50%
$150
6
physician c
treatment assumed to occur 5 years after onset of infection
duration of condition: remaining lifetime
50%
$500
1
diagnostic c
50%
$250
1
procedure
outpatient laparoscopy (75% of those seeking treatment)
38%
$1,000
1
hospitalization
38%
$500
1
surgical staff
38%
$500
1
surgical staff
tubal surgery (30% of those seeking treatment)
15%
$1,000
1
outpatient surgery
15%
$500
1
surgeon
15%
$500
1
anesthesiology
in vitro fertilization (12% of those seeking treatment)
6%
$4,000
2
per trial
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% with Care
Cost per Unit
Units per Case
Form of Treatment
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —outpatient
100%
$100
2
physician b
100%
$50
1
culture—gonorrhea
100%
$50
1
medication
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —inpatient
100%
$3,000
1
hospitalization
100%
$150
3
physician c
100%
$50
1
diagnostic a
100%
$50
1
medication b
outpatient after inpatient
$100
1
physician b
MEN
Asymptomatic (untreated) Urethritis
100%
$50
1
physician a
100%
$50
1
diagnostic a
Epididymitis
outpatient
100%
$100
1
physician b
100%
$50
1
physician a
100%
$50
1
diagnostic a
100%
$50
1
medication b
Epididymitis
inpatient
100%
$3,000
1
hospitalization
100%
$150
3
physician c
100%
$50
1
physician a
100%
$50
1
medication b
50%
$500
1
surgical staff
50%
$500
1
surgical staff
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —outpatient
100%
$100
2
physician b
100%
$50
1
culture—gonorrhea
100%
$50
1
medication
Disseminated gonococcal infections (bacteremia, arthritis, etc.) —inpatient
100%
$3,000
1
hospitalization
100%
$150
3
physician c
100%
$50
1
diagnostic a
100%
$50
1
medication b
outpatient after inpatient
$100
1
physician b
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30% were presumed to undergo abdominal surgery. For the purposes of the calculations in this report, it was assumed that half of women infertile due to gonorrhea infection seek some kind of medical care related to infertility. This includes hysterosalphoingography, outpatient laparoscopy, tubal surgery, and infertility treatment.
Epididymitis in men was estimated to be treated primarily on an outpatient basis and includes costs for both limited visits and specialist physician visits, diagnostics, and medications. For the few patients who undergo surgery, costs for surgeons and anesthesiologist are included.
VACCINE DEVELOPMENT
The committee assumed that it will take 15 years until licensure and that $360 million needs to be invested. Table 4–1 summarizes vaccine development assumptions for all vaccines considered in this report.
VACCINE PROGRAM CONSIDERATIONS
Target Population
For the purposes of the calculations in this report, it is assumed that the target population for this vaccine is adolescents (age 12 years). It was assumed that 50% of the target population would utilize the vaccine.
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
If a vaccine program for N. gonorrhea 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 230,000. 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 47,000. Although the proportion
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of cases are slightly higher in men than in women, the number of QALYs lost due to disease in women is over 200 fold that in men. The more severe nature of the sequelae of infection in women and the chronic nature of several of the sequelae account for this large difference.
If a vaccine program for N. gonorrhea 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 $440 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 $92.1 million.
If a vaccine program for N. gonorrhea 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 $680 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 $190 million.
Using committee assumptions of time and costs until licensure, the fixed cost of vaccine development has been amortized and is $10.8 million for a N. gonorrhea 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 $1,000. 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 $2,300.
See Chapters 4 and 5 for details on the methods and assumptions used by the committee for the results reported.
READING LIST
Alexander LL, Treiman K, Clarke P. A National Survey of Nurse Practitioner Chlamydia Knowledge and Treatment Practices of Female Patients. Nurse Practitioner 1996; 21:48, 51–4.
Gutman, LT. Gonorrhea. In: Textbook of Pediatric Infectious Diseases. RD Feigin and JD Cherry eds. Philadelphia, PA: WB Saunder Company, 1992, pp. 540–552.
Handsfield HH, Sparling PF. Neisseria Gonorrhoeae. In: Principles and Practice of Infectious Diseases. GL Mandell, JE Bennett, Dolin R eds. New York, NY: Churchill Livingstone, 1995, pp. 1909–1926.
Magid D, Douglas JM, Schwartz JS. Doxycycline Compared with Azithromycin for Treating Women with Genital Chlamydia Trachomatis Infections: An Incremental Cost-Effectiveness Analysis. Annals of Internal Medicine 1996; 124:389–99.
U.S. Bureau of the Census. Statistical Abstract of the U.S.: 1995 (115th edition). Washington, D.C. 1995.
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