Background Success with biological agents could be measured by the proportion of people who achieve and maintain a 75% reduction in Psoriasis Area and Severity Index (PASI-75). In patients with a positive response to the treatment (PASI-75), increasing the dose intervals can reduce treatment costs without affecting the efficacy of the drug.

Purpose To evaluate the medication persistence to biological treatments in patients with moderate to severe psoriasis.

To calculate costs savings in selected patients with increased dose intervals.

Material and methods This was a retrospective observational study conducted in the outpatient pharmacy of a tertiary hospital. Eligible patients were those with moderate to severe psoriasis who had received any biological agent between January and August 2016. Collected data were: demographic variables (age, gender), disease variables (PASI) and treatment variables (current biological drug to treat psoriasis, and dose, frequency of administration and medication persistence of the drug). In patients with PASI-75, costs savings due to increased dose intervals or dose reductions were calculated.

Results 102 (72% men) were included with a median age of 47.5 years (39–54). 49 (48%) were taking ustekinumab, 31 (30%) adalimumab, 20 (20%) etanercept, 1 (1%) golimumab and 1 (1%) secukinumab. For 67 patients (66%) this was their firstline treatment. Medication persistence was 1071 days (472–2362) for etanercept, 993 days (372–1535) for ustekinumab and 827 days (487–1848) for adalimumab. The frequencies of administration were 7 days (7–7) for etanercept, 14 (14–23) for adalimumab and 98 (91–98) for ustekinumab. Median reduction in PASI was −87% (−71%; −100%).

In 56 patients (55%) the physician increased the dose interval; 40 (81%) were taking ustekinumab with a dose interval of 98 days (91–105), 12 (39%) adalimumab every 28 days (21–38) and 4 etanercept (20%) every 10 days (9.5–10). This represented a total cost saving of €223 366/year (€66 893 for ustekinumab, €129 525 for adalimumab and €26 948 for etanercept). Median reduction in PASI in patients with increased dose intervals was −89% (−70%; −100%).

Conclusion Medication persistence for ustekinumab and etanercept was higher than that for adalimumab. Increasing dose intervals in patients with a positive response to the treatment is a useful strategy to reduce costs and maintain effectiveness.

No conflict of interest