Cost-effectiveness Analysis in Pertussis Vaccination and Treatment of Chronic Viral Hepatitis in Taiwan

• Main Authors: Raoh-Fang Pwu, 蒲若芳
• Other Authors: K. Arnold Chan
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/46840826499416267689

博士 === 國立臺灣大學 === 流行病學研究所 === 90 === Background Along with aging of the population, industrialization of the society, and implementation of the National Health Insurance, the Taiwan health care system is facing the same challenge as in all industrialized countries, which is to equitably and optimally allocate limited health care budget. Cost-effectiveness analysis, the scientific method that takes into account all available evidence of viable alternatives, has been widely used in the formulation of health care policy in many countries. Objectives This disseration aimed to bring in the concept and experiences of cost-effectiveness analysis to aid health care decision-making. Three consecutive studies utilizing the methodology has therefore proposed: 1) the economic evaluation for the use of the 4th dose of acellular (DTaP) or whole-cell Diphtheria-Tetanus-Pertussis (DTP) vaccine; 2) the cost-effectiveness analysis of interferon alpha therapy in the treatment for chronic hepatitis B; 3) the cost-effectiveness analysis of alpha interferon / ribavirin as initial treatment for chronic hepatitis C. Methods 1) A decision tree was built to calculate the expected costs and consequences of the DTP and DTaP vaccine alternatives. Using a societal perspective, the cost per adverse event averted and cost per life quality score gained were estimated. 2) For the evaluation of the interferon therapy in chronic hepatitis B patients, a Markov model was constructed. Through systematic reference searches and reviews, the parameters were decided and utilized in the model. The discounted lifetime costs and quality-adjusted life years for the competing alternatives were simulated. The incremental cost-effectiveness ratios (ICERs) were used as the primary endpoint. Utilizing one-way sensitivity analysis, the influential parameters were identified. The uncertainty of the ICERs was estimated from Monte Carlo simulations. 3) In the evaluation of the interferon/ribavirin combination therapy for chronic hepatitis C patients, we also utilized the Markov model approach. ICERs were the analysis endpoint; cost per QALY gained has been therefore estimated. Both one-way sensitivity analyses and probability sensitivity analyses were done to assess the uncertainty of the results. Acceptability curves were presented for comparing the alternatives. Results 1) Total medical expenses related to the vaccinations were higher in DTaP, but the effectiveness and utility scores were also higher. Since the adverse reaction (ADR) rate is lower in DTaP group, the results for the cost-effectiveness analysis was 90~130 NT dollars (about US$ 3~4) per ADR prevented. However, the ADRs studied here were rather mild, therefore the gains in quality of life were quite small. The cost-utility analysis resulted in a NTD 1,500~2,000 (US$ 45~60) cost per one baby’s quality of life score gained, as well as a NTD 1,800~2,500 (US$ 55~76) cost per one family’s quality of life point gained. 2) For the base case, a 35-year-old chronic hepatitis B patient treated with interferon in Taiwan would have life expectancy of 29.08 years, versus 28.67 years for those who did not receive interferon. Corresponding to this gain in life expectancy of 0.41 years (or 0.18 QALYs), the ICER was 492,000 NTD per QALY with an annual 3% discount rate. Based on Monte Carlo simulation that takes into account the range of plausible values for all model parameters, 95% of the ICERs lied in the range of 65,000 NTD/QALY to 683,000 NTD/QALY, and 90% of the ICERs were below 413,000 NTD/QALY. 3) In the base case analysis, a 45-year-old chronic hepatitis C patient in Taiwan would have a life expectancy of 30.56 years, or 31.26 years if he/she receives the 24-week or the genotype-dependent combination therapies, comparing with 30.17 years from the standard no antiviral treatment. The lifetime costs for the three groups were estimated to be NTD 975,000, 709,000, and 677,000, respectively. While the two combination therapies compares with no treatment are cost-saving options, the genotype-dependent combination therapy has an ICER about 93,255 NTD/QALY when comparing with the 24-week combination therapy. Both one-way sensitivity analysis and probabilistic sensitivity analyses supported the robustness of the study results. Conclusions New technology in health care and medicine may prolong lives and improve life quality. “At what prices”, however, is the main issue for the decision makers nowadays. There has been very little work presented about economic evaluation for new drugs/technology in Taiwan. This dissertation serves as a first step to rigorously evaluate the relative merit of public health interventions or disease management regimens in this area.