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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



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Vaccines for the 21st Century: A Tool for Decisionmaking 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

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Vaccines for the 21st Century: A Tool for Decisionmaking 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

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Vaccines for the 21st Century: A Tool for Decisionmaking 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.

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Vaccines for the 21st Century: A Tool for Decisionmaking 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.

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Vaccines for the 21st Century: A Tool for Decisionmaking 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.

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Vaccines for the 21st Century: A Tool for Decisionmaking 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.