APPENDIX 21
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is a chronic multisystem disease which can have a variety of systemic manifestations. Persistent inflammatory synovitis, however, is the characteristic feature of RA, which usually involves the peripheral joints. Most often, the joints of the hands, wrists, knees, and feet are involved and are usually affected in a symmetrical fashion. The synovial inflammation can potentially destroy the cartilage and cause bone erosion, which subsequently leads to joint deformities. The destructive nature of this disease ranges from a brief oligoarticular illness with minimal joint damage to a more chronic, progressive polyarthritis with major joint deformity.
DISEASE BURDEN
Epidemiology
For the purposes of the calculations in this report, the committee estimated that there are approximately 65,000 new cases of rheumatoid arthritis each year in the United States. The incidence is highest in people 55 years of age and older, but new cases were included for people between the ages of 15 and 54 years of age as well. See Table A21–1.
Disease Scenarios
For the purposes of the calculation in this report, the committee assumed that there are four disease scenarios associated with RA. A relatively benign
Table A21–1 Incidence Rate for Rheumatoid Arthritis
Age Groups |
Population |
Incidence Rates (per 100,000) |
Cases |
<1 |
3,963,000 |
0.0 |
– |
1–4 |
16,219,000 |
0.0 |
– |
5–14 |
38,056,000 |
0.0 |
– |
15–24 |
36,263,000 |
2.0 |
725 |
25–34 |
41,670,000 |
9.0 |
3,750 |
35–44 |
42,149,000 |
17.0 |
7,165 |
45–54 |
30,224,000 |
38.5 |
11,636 |
55–64 |
21,241,000 |
74.0 |
15,718 |
65–74 |
18,964,000 |
80.0 |
15,171 |
75–84 |
11,088,000 |
71.0 |
7,872 |
85+ |
3,598,000 |
71.0 |
2,555 |
Total |
263,435,000 |
24.5 |
64,594 |
form experienced by 15% of people with RA is associated with a health utility index (HUI) of .91 for 1 year. A moderate form of RA experienced by 65% of the patients was associated with lifelong disease at an HUI of .72. It was assumed that there was premature death by 3 years in these patients.
For 15% of RA patients who experience a progressive disease, it was assumed that the remainder of life was spent in an average HUI of .49. Life expectancy was shortened by 5 years in these patients. For 5% of patients, RA manifests with severe systemic manifestations and is associated with an HUI of .33. Life expectancy was assumed to be decreased by 7 years in these patients. See Table A21–2.
COST INCURRED BY DISEASE
Table A21–3 summarizes the health care costs incurred by RA. For the purposes of the calculations in this report, it was assumed that initial treatment for all RA patients includes 4 visits to a physician (half will seek the attention of a specialist), medication, and diagnostic evaluation. Patients with a limited, benign course seek no further treatment. Yearly health care costs for patients experiencing chronic, moderate disease were assumed to include semi-annual visits to a physician (50% to a specialist) and medication. It was assumed that on average, each year 10% of patients would require hospitalization and rehabilitation services. Annual care for patients with progressive, serious disease was assumed to include quarterly visits to a specialist, medication, and hospitalization and rehabilitation services for 25% of patients. Annual care for patients with severe systemic disease was assumed to be associated with bimonthly visits to a
Table A21–2 Disease Scenarios for Rheumatoid Arthritis
|
No. of Cases |
% of Cases |
Committee HUI Values |
Duration (years) |
Benign |
9,689 |
15.00% |
|
|
short-term pain, resolved within 1 year |
|
0.91 |
1.0000 |
|
Moderate disability |
41,986 |
65.00% |
|
|
joint involvement |
|
0.72 |
19.4924 (life expectancy at onset) |
|
premature death: reduction in life expectancy by 3 years |
|
0.00 |
3.0000 |
|
Progressive |
9,689 |
15.00% |
|
|
seriously affected within 5–10 years of diagnosis |
|
0.49 |
17.4924 (life expectancy at onset) |
|
premature death: reduction in life expectancy by 5 years |
|
0.00 |
5.0000 |
|
Severe systemic manifestations |
3,230 |
5.00% |
|
|
joint involvement; complications may include pulmonary and cardiac involvement |
|
0.33 |
15.4924 (life expectancy at onset) |
|
premature death: reduction in life expectancy by 7 years |
|
0.00 |
7.0000 |
specialist, medication, and hospitalization and rehabilitation services for 50% of patients.
VACCINE DEVELOPMENT
The committee assumed that it will take 15 years until licensure of a therapeutic RA vaccine and that $360 million needs to be invested. Table 4–1 summarizes vaccine development assumptions for all vaccines considered in this report.
Table A21–3 Health Care Costs Associated with Rheumatoid Arthritis
|
% with Care |
Cost per Unit |
Units per Case |
Form of Treatment (per year) |
Benign |
|
|||
short-term pain, resolved within 1 year |
50% |
$50 |
4.0 |
physician a |
|
50% |
$100 |
4.0 |
physician b |
100% |
$50 |
12.0 |
medication b |
|
100% |
$500 |
1.0 |
diagnostic c |
|
Moderate disability |
|
|||
initial treatment |
50% |
$50 |
4.0 |
physician a |
|
50% |
$100 |
4.0 |
physician b |
100% |
$50 |
1.0 |
medication b |
|
100% |
$500 |
1.0 |
diagnostic c |
|
annual care |
50% |
$50 |
2.0 |
physician a |
|
50% |
$100 |
2.0 |
physician b |
100% |
$50 |
12.0 |
medication b |
|
10% |
$3,000 |
1.0 |
hospitalization |
|
10% |
$3,000 |
1.0 |
rehabilitation or other care |
|
Progressive |
|
|||
initial treatment |
50% |
$50 |
4.0 |
physician a |
|
50% |
$100 |
4.0 |
physician b |
100% |
$50 |
1.0 |
medication b |
|
100% |
$500 |
1.0 |
diagnostic c |
|
annual care |
100% |
$100 |
4.0 |
physician b |
|
100% |
$50 |
12.0 |
medication b |
25% |
$3,000 |
1.0 |
hospitalization |
|
25% |
$3,000 |
1.0 |
rehabilitation or other care |
|
Severe systemic manifestations |
|
|||
initial treatment |
50% |
$50 |
4.0 |
physician a |
|
50% |
$100 |
4.0 |
physician b |
100% |
$50 |
1.0 |
medication b |
|
100% |
$500 |
1.0 |
diagnostic c |
|
annual care |
100% |
$100 |
6.0 |
physician b |
|
100% |
$50 |
12.0 |
medication b |
50% |
$3,000 |
1.0 |
hospitalization |
|
50% |
$3,000 |
1.0 |
rehabilitation or other |
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 all new cases of RA. It was assumed that 90% 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 $500 per dose and that administration costs would be $10 per dose. Default assumptions for a therapeutic vaccine of a 3-dose series and 40% effectiveness were accepted. Table 4–1 summarizes vaccine program assumptions for all vaccines considered in this report.
RESULTS
If a vaccine program for rheumatoid arthritis 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 275,000. 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 60,000. Most of the QALY loss was attributed to the moderate form of the disease, due to the proportion of cases experiencing that scenario and the long time spent at a moderately decreased HUI.
If a vaccine program for rheumatoid arthritis 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 $1.4 billion. 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 $300 million.
If a vaccine program for rheumatoid arthritis 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 $100 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 $53.8 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 rheumatoid arthritis 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 -$5,000. A negative value represents a saving in costs in addition to a saving in QALYs. 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 -$4,000.
See Chapters 4 and 5 for details on the methods and assumptions used by the committee for the results reported.
READING LIST
Chan KW, Felson DT, Yood RA, et al. Incidence of Rheumatoid Arthritis in Central Massachusetts. Arthritis and Rheumatism 1993; 36:1691–6.
Prashker MJ, Meenan RF. The Total Costs of Drug Therapy for Rheumatoid Arthritis: A Model Based on Costs of Drug, Monitoring, and Toxicity. Arthritis and Rheumatism 1995; 38:318–25.