To evaluate the precision of the predictive cost-effectiveness assessment based on a phase 3 clinical trial with infliximab for the treatment of rheumatoid arthritis in Swedish clinical practice.
Three patient cohorts were identified: the patients included in the infliximab trial (ATTRACT), patients initially treated with infliximab from a Swedish registry (STURE), a subset of these registry patients meeting inclusion criteria for the ATTRACT trial was the third patient cohort; two sets of assumptions in relation to the efficacy data were evaluated: “ATTRACT” (efficacy data over the duration of the trial) and “STURE” (effectiveness data over 10 years). In addition, the impact of including the placebo effect for the comparator was evaluated as a basis for the calculation of cost-effectiveness by using a modeling approach. A health economic model was utilized to estimate the cost per quality-adjusted life-year (QALY) gained.
The results for the three patient cohorts ranged from cost saving to a cost per QALY gained of €2,400 and €24,900 to €26,000 when the ATTRACT and STURE assumptions were used, respectively. Sensitivity analyses indicated that the inclusion of placebo effect had the largest effect on the results, increasing the cost per QALY gained to approximately €50,000 for all patient cohorts.
The treatment effect of infliximab measured in clinical trials and clinical practice results in comparable cost-effectiveness ratios, as calculated by using a modeling approach, whereas the assumptions made in relation to the effectiveness data and the chosen comparator have a large impact on the results. This reinforces the value of early modeling studies based on randomized clinical trial data, but assumptions made need to be carefully assessed.