During the past few decades two treatment strategies have evolved for patients with unstable coronary artery disease (UCAD). The non-invasive strategy uses clinical investigations and non-invasive stress tests to identify patients who need diagnostic catheterisation. The early invasive strategy uses coronary catheterisation as the diagnostic instrument. The new technologies have consequences not only for the clinical endpoints of death or myocardial infarction (MI), but also in terms of health-related quality of life and costs. The economic evaluations are of great importance due to the high incidence of the disease and high short-term costs of the invasive strategy. The early costly intervention may prevent later complications and thereby partly or completely offset the higher initial treatment costs. Even if longterm costs remain higher, they can be justified by improved survival or quality of life. Such clinical effects in the long-term follow-up need to be seen in relation to the cost of the strategy. In a prospective Scandinavian multi centre trial we examined 3489 patients with UCAD. The purpose of this thesis was to study the treatment strategies in UCAD with respect to cost-effectiveness and patients' health-related quality of life. This purpose was divided into four aims:
The first aim was to evaluate the cost-effectiveness of extended treatment with the low-molecular-weight heparin dalteparin. 2267 patients were randomised. The incremental cost-effectiveness ratio for administering dalteparin treatment for one month was SEK 30,300 per avoided death or MI. Since the resources for early intervention are limited in many countries, extended dalteparin treatment for up to one month is a cost-effective bridge to invasive intervention.
The second aim was to evaluate the short-term costs and cost-effectiveness of the invasive strategy compared to the non-invasive strategy. A total of 2457 patients were randomised. The results were analysed in a societal perspective. The difference in mean total costs after one year was SEK 23,900 (p < 0.001), favouring the non-invasive strategy. The incremental cost-effectiveness ratio for choosing the invasive instead of the non-invasive strategy was SEK 645,000 per avoided death or MI. The high cost at the beginning of the invasive strategy was substantial. For policy discussions concerning implementing the invasive strategy, these positive results should be balanced against the cost-consequences of the strategy.
The third aim was to evaluate the patients' health-related quality of life with respect to the strategies. We used two questionnaires, the generic Short Form 36 (SF-36) and the disease-specific Angina Pectoris Quality of Life Questionnaire (APQLQ), at randomisation and after three, six and 12 months of followup. The invasively treated group showed a significantly better health-related quality of life at the threeand six-month follow-ups (p < 0.01) than the non-invasively treated group. These differences remained at the 12-month follow-up. The disease-specific quality of life results were similar.
The fourth aim was to evaluate the long-term cost-effectiveness and cost-utility of these strategies. Results were analysed in both a societal and a health care provider perspective. The difference in mean total cost SEK 11,400 was not statistically significant. The estimated cost per quality adjusted life year (QALY) gained for the invasive strategy, based on within trial results and projected life expectancy, was SEK 22,900. These results were consistent in most subgroups. The estimated cost per life year gained was SEK 57,700. Compared to other accepted treatments in the cardiovascular field, the cost per QALY gained is very low.
In summary, this thesis shows that the early invasive treatment strategy for patients with UCAD promotes health-related quality of life and is highly cost-effective when compared to many other interventions in the cardiovascular field and should therefore be recommended.
Linköping: Linköpings universitet , 2003. , 176 p.
2003-10-17, Elsa Brändströmsa sal, Universitetssjukhuset, Linköping, 13:00 (Swedish)