The aim of this study was to calculate the marginal cost of dose escalation in people with rheumatoid arthritis treated with tumour necrosis factor (TNF) inhibitors across Europe.
The proportion of people who escalate their dose of TNF inhibitor and the average percentage increase in TNF inhibitor cost associated with escalators versus non-escalators was calculated from previously published estimates, weighted by the sample size for each study. The number of people with rheumatoid arthritis treated with TNF inhibitors and the corresponding total drug sales were obtained for five European countries from Decision Resources' Pharmacor Market Forecast. Method 1 assumed that total sales of a TNF inhibitor represented the cost of an escalator multiplied by the number of escalators plus the cost of a non-escalator multiplied by the number of non-escalators. Method 2 assumed that the drug cost per day used to forecast total sales was calculated using the dose of TNF inhibitor used by non-escalators. The marginal cost of TNF inhibitor dose escalation was estimated by multiplying the difference in cost between escalators and non-escalators by the number of escalators.
The estimated increase in TNF inhibitor costs associated with dose escalation in people with rheumatoid arthritis across five European countries (Germany, France, UK, Spain and Italy) was €51.5-54.4 million for adalimumab, €44.8-52.8 million for infliximab and €5.8-5.9 million for etanercept.
Dose escalation of the TNF inhibitors adalimumab, etanercept and infliximab in people with rheumatoid arthritis has resulted in an increase in TNF inhibitor costs across five European countries.