Background/Purpose: Limited information exists on the long term real-world treatment patterns of biologics for psoriatic arthritis (PsA) in the US population. We assessed medication persistence and drug switching with biologics in PsA and estimated the economic costs of different treatment sequences.

Methods: We conducted a retrospective analysis of medical and pharmacy claims data from the MarketScan database (United States).  The study included PsA patients >= 18 years of age, biologic-naïve (no biologic therapy in the previous 6 months), who initiated a biologic during the period from October 1, 2009 to September 30, 2010 and were continuously enrolled in a medical and pharmacy benefits program for a 3-year follow-up period. Treatment persistence, switching, modification of treatment (i.e., biologic dose adjustment or any change in concomitant DMARD therapy), and medical and pharmacy costs were analyzed for each line of biologic therapy during the  3 year follow-up period. Line of therapy was defined by the number of biologics a patient used in the follow-up peroid.

Results: Among the 990 PsA patients identified 89.0% of patients used only one line of biologic, 7.3% had a second-line biologic, and 3.7% tried 3 or more lines of biologic therapy. For all the lines of therapy, the first biologics used were: etanercept (n = 435; 43.9%), adalimumab (n = 437; 44.1%), infliximab (n = 77; 7.8%), and golimumab (n = 41; 4.1%).  The discontinuation rates by line of therapy were as follows: 71.6% (n = 631) for patients who only used one line of biologics; 50.0% (n = 36) for those with second-line biologic and 18.9% (n = 7) for those who tried 3 or more biologics.The time patients spent on the first biologic was shorter  for those who switched to a second-line biologic (348 days) or third-line biologic (325 days) compared to those those who only used one biologic (522 days). Overall time to treatment modification became shorter with each line of therapy; the shortest was 42 days for patient on their third line of therapy, 137 days for those on their second line, and 146 days in the first line. The most common treatment modifications in the first-line of biologic therapy were DMARD dose increase (21.1%), add-on (9.0%) and removal (7.4%). Monthly medical costs (hospitalizations, office visits, emergency department visits) per member per month were higher for patients using only one line of biologic ($322) than for those who received second-line ($167) or third-line ($217) treatment, whereas monthly pharmacy costs per member per month were lower for patients using only one line of  biologic ($1985) than for those on second-line ($2045) or third-line ($2539) biologics.

Conclusion: Approximately two thirds of PsA patients discontinued their first biologic therapy. Of those who were continuous users and and moved on to second- and third-line therapies, the time of discontinuation from their  first-biologic was shorter, indicating non-responders were identified early in the treatment course. Monthly medical costs were higher for those who did not switch biologic therapy, but pharmacy costs increased with the number of biologic switches. This may be because of treatment add-ons or worsening disease severity.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/modifications-to-biologic-therapy-and-economic-implications-in-psoriatic-arthritis-patients/