When deciding on therapy for a chronic disease, physicians typically attempt to consider both the short-term and long-term effects. Although the short-term effects are often relatively easy to anticipate, long-term effects are more difficult. Moreover, many clinical studies and cost-effectiveness models include only the short-term effects of therapy, meaning that physicians are missing important data as they make their treatment decisions.
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In the case of rheumatoid arthritis (RA), physicians and patients seek long-term benefits, such as prevention or slowing of the radiographic progression of RA. However, absent data on long-term benefits, physicians typically prescribe for the short term. For example, in the United Kingdom (UK), patients who are diagnosed with RA are prescribed an initial therapy with a disease-modifying antirheumatic drug (DMARD), such as methotrexate, and then are later offered biologic drugs. The switch to biologics occurs only after a period of time and only if the patient does not respond to DMARDs. Researchers are now questioning this strategy and asking if there is a better way to model the long-term effects of therapy.
Stephanie Stephens, MSc, Director Health Economics & Outcomes Research at Pharmerit Ltd. in the UK, and colleagues modeled the short- and long-term effects of methotrexate (MTX) compared with a combination therapy of MTX plus adalimumab. They published the results of their cost-effectiveness model of patients with early RA online June 9, 2015, in BMJ Open.1 The researchers designed their model to create a unifying view of both short-term and long-term outcomes. The model also attempts to integrate both the reversible and irreversible effects of RA. The investigators based the model on data from patients from the PREMIER trial who were classified as having early, aggressive RA. The model was also based on clinical pathways (DMARDs followed by biologics) typically used to treat RA in the UK.
Stephens and colleagues found that the combination of adalimumab with MTX is a good initial treatment strategy for early, aggressive RA. Specifically, the investigators estimated that combination therapy produced six-month ACR50 responses in 75% of patients. By contrast, only 54% of patients in the MTX-only group achieved a six-month ACR50 response. When compared with MTX mono-therapy, combination therapy resulted in a gain of 2.68 discounted life-years and 3.04 quality-adjusted life-years (QALY).
The combination therapy was cost effective when irreversible damage was included in the calculation. Specifically, the combination therapy resulted in a net increase in direct costs of £106,207, which translated into an incremental cost/QALY gain of £32,425. When the researchers included such indirect costs as a UK societal perspective, the incremental cost-effectiveness ratio (ICER) on combination therapy decreased to £27,238/QALY gained. When the investigators disregarded irreversible effects and included only direct costs, the incremental cost-effectiveness ratio increased to £78,809.