Background/Purpose: Etanercept (ETN) and Adalimumab (ADA) are commonly used biologic disease-modifying antirheumatic drugs (DMARDs) for psoriatic arthritis (PsA) patients (pts). However, little is known about subsequent treatment changes after the initiation of these two biologics. The objective of this study was to describe treatment patterns following the initiation of ETN and ADA in PsA patients in US in a real-world setting.

Methods: Adult PsA pts were selected from MarketScan Commercial Claims database (2005-2009). First ETN/ADA prescription date was defined as the index date. Pts were required to have continuous enrollment 6-month prior to (baseline period) and 12-month post index date (study period), no use of the index biologic treatment during baseline, have received ≥2 PsA diagnoses from physician office visits at any time over the 18-month period, with at least one PsA diagnosis during baseline period, and no diagnosis of ankylosing spondylitis. ETN/ADA combo therapy was defined as having at least 28 days of concomitant use of a non-biologic DMARD following the index date; otherwise ETN/ADA monotherapy was defined. Treatment patterns were captured over the 12-month study period and were defined as the following: complete treatment discontinuation — a treatment interruption of ≥60 consecutive days past the end of the days’ supply (discontinuation date) and no other DMARD therapy between the discontinuation date and the end of the study period; a switch in therapy — the initiation of a new non-biologic/biologic DMARD (not used during baseline) within 60 days of the discontinuation date; intermittent use of the index biologic — ≥60 days of treatment gap of the index biologic; step-down — discontinuation of one of the DMARD therapies among patients previously on combo therapy; step-up — adding another DMARD (not used during baseline) concomitantly with the index biologic for ≥28 consecutive days. Therapy modification was defined as any switch, intermittent use, step-down or step-up.

Results: A total of 2,037 and 2,217 PsA pts were newly initiated on ETN and ADA respectively, most on monotherapy (ETN: 69.2%, ADA: 67.5%). Over the 12-month study period, the majority of the pts had ≥ 1 therapy change (ETN: 65.3%, ADA: 69.1%), with median time to change 113 days and 112 days respectively. Among pts initiated on mono ETN/ADA, 40.7% ETN and 33.5% ADA pts remained on the index mono therapy. 12.1% ETN and 11.6% ADA pts discontinued the treatment, 18.2% ETN and 14.7% ADA pts had intermittent treatment, 7.0% ETN and 11.4% ADA pts switched to another mono therapy, and 21.9% ETN and 29.1% ADA pts step-up to combo therapy. Among pts initiated on ETN/ADA in combination with an oral DMARD, a proportion of pts remained on the original combo therapy (ETN: 21.4%, ADA: 26.8%). The majority of the patients ‘stepped down’ to monotherapy (ETN: 77.5%, ADA: 72.7%). Very few pts discontinued both drugs in the combo therapy (ETN: 0.5%, ADA: 0.1%) or adopting intermittent biologic therapy (ETN: 0.6%, ADA: 0.3%).

Conclusion: This study suggests that most of the PsA patients newly initiated on ETN or ADA have a therapy change over the first year. Both ‘step-up’ and ‘step down’ strategy are observed frequently.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/us-treatment-patterns-of-psoriatic-arthritis-patients-newly-initiated-on-etanercept-or-adalimumab/