Authors: Lee S, Xie L, Wang Y, Vaidya N, Baser O.

Background: Psoriasis is a chronic, hyper-proliferative dermatological condition associated with joint symptoms known as psoriatic arthritis (PsA). In a 2013 review, the total economic burden of PsA was estimated at $51.7-$63.2 billion. The economic burden of moderate to severe psoriasis patients has reduced significantly with the advent of biologics, but there remains a dearth of real-world evidence of the impact of treatment persistence on the economic burden of moderate to severe psoriasis and/or PsA patients.

Objective: To evaluate the overall and psoriasis and/or PsA-related health care utilization and costs among patients who were persistent versus those nonpersistent on index biologic among the moderate to severe psoriasis and/or PsA population.

Methods: Adult patients with ≥ 2 claims with diagnosis of psoriasis and/or PsA during the period of November 2010-October 2015 were identified from the U.S. Department of Defense database; the first diagnosis date during November 2011-October 2014 was defined as the index date. As of the index date, patients were considered to have moderate to severe psoriasis or PsA if they had ≥ 1 nontopical systemic therapy or phototherapy during the 1-year pre- or 1-month post-index date. Persistence to index therapy, defined as the first biologic used (etanercept, adalimumab, ustekinumab, infliximab) on or within 30 days post-index date, was determined based on the biologic dosing schedule and a 90-day gap. Generalized linear models were used to compare the health care utilization and costs between persistent and nonpersistent patients during the 1-year post-index period.

Results: A total of 2,945 moderate to severe psoriasis and/or PsA patients were identified. Of those, 1,899 (64.5%) were persistent and 1,046 (35.5%) were nonpersistent. Compared with nonpersistent patients, persistent patients were older (49.2 vs. 45.5 years; P < 0.001) and more likely to be male (52% vs. 45%; P < 0.001). More persistent patients were diagnosed with dyslipidemia (40% vs. 35%; P = 0.002), had lower antidepressant use (23.4% vs. 27.4%; P < 0.001), and had lower anxiolytic use (30% vs. 37%; P < 0.001) compared with nonpersistent patients. After adjusting for demographic and clinical characteristics, nonpersistent patients had higher total medical costs ($12,457 vs. $8,964; P < 0.001) compared with persistent patients, and ambulatory visits (23.9 vs. 21.4; P = 0.007) were a major contributor. Approximately 40% of the total overall medical costs were attributed to psoriasis and PsA. Although persistent patients incurred higher pharmacy costs ($10,684 vs. $7,849; P < 0.001) due to higher biologic use and the potentially high per-unit cost of biologics, their psoriasis- and/or PsA-related medical costs were significantly lower than those of nonpersistent patients ($3,395 vs. $5,041; P < 0.001). Total overall costs combining medical and pharmacy costs were similar between the cohorts ($22,678 vs. $21,477; P = 0.122).

Conclusions: Moderate to severe psoriasis and/or PsA patients who were persistent on index biologic treatment had higher pharmacy utilization and costs, albeit with lower medical costs and similar total costs, compared with nonpersistent patients.

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