Aims: Existing treatment-sequence models for psoriasis are limited by lines of treatments included. We sought to more accurately capture the patient experience with an increasing number of treatments while maintaining the complexity and transparency of current models.
Materials and methods: We adapted a standard treatment-sequence model for psoriasis with two lines of active treatments followed by best supportive care (BSC). The first line was used to model the targeted treatments for comparison (Biologic A or B). The second line was used potentially to model all treatments (excluding the first-line treatment) before BSC, termed the basket of biologics (BoB). First-line treatment and the BoB were modeled with an induction and maintenance phase. The BoB efficacy was assumed to be the average of all treatments included and the BoB annual discontinuation rate was based on the number of treatments included and their individual annual discontinuation rate. A varying number of treatments in the BoB were tested (1, 5, 10). Model inputs were from published literature.
Results: In our example, when the number of treatments in the BoB increased from 1 to 10, the annual discontinuation rate of the BoB dropped from 16.5% to 1.2%. Time on BoB increased from 4.16 to 19.16 years and the time on BSC decreased from 28.28 to 13.29 years. Total costs and quality-adjusted life years increased with an increasing number of treatments in the BoB.
Limitations: The properties of the BoB were simplified in order to maintain the transparency of the model. Results may differ if individual treatments in the BoB are modeled line by line.
Conclusions: Modification with the BoB allows a greater number of treatments within the model, providing a closer reflection of clinical reality, and has implications for evaluation of the long-term cost-effectiveness of psoriasis treatments.
Keywords: C; C5; C52; C6; C63; Economic evaluation; cost-effectiveness; psoriasis; treatment discontinuation; treatment sequence model.
Psoriasis is a chronic skin disease with no cure that causes itchy and painful plaques and scales, most commonly found on the scalp, trunk, elbows, and knees. A variety of treatments are available that can improve the signs and symptoms of psoriasis. Healthcare payers are interested in the costs, benefits, and risks of treatments for all diseases, including those for psoriasis. These payers often use mathematical models to better understand and compare the value of various treatments. With psoriasis, these models usually assume three lines of active therapy and then a final supportive therapy over a patient’s lifetime. However, the average number of therapies patients with psoriasis receive is often greater than three, resulting in them spending most of their time on, and switching among, treatments rather than on best supportive care. Therefore, instead of modeling each line of treatment individually, the researchers proposed a modification to the existing model framework, whereby all subsequent treatments are combined into a single basket. This modification allowed for many treatments to be considered over the lifetime of patients with psoriasis and also maintained the model’s complexity. The researchers found that as the amount of time on active therapy increased, the amount of time on supportive therapy decreased, treatment costs increased, and patients spent more time with better quality-of-life. The researchers concluded that the proposed model modification more closely resembles clinical practice than the previous model and would be very useful to healthcare payers in better estimating the value of psoriasis treatments.