Real-World Study Examines Treatment Patterns of 2 Biologics for Psoriasis

A recent retrospective cohort study compared treatment patterns between ixekizumab and adalimumab among patients with moderate to severe psoriasis using real-world data in the United States.

Adalimumab (Humira) is a tumor necrosis factor (TNF) inhibitor; ixekizumab (Taltz) is an interleukin-17A (IL-17) inhibitor. The authors said this is the first direct comparison of ixekizumab, approved by the FDA in 2016, and adalimumab.

The analysis examined treatment persistence, adherence, discontinuation, switching, and restart; it was performed using patient-level administrative claims data extracted from IBM Watson Health MarketScan databases. Patients with 1 or more claims for the 2 drugs between March 1, 2016, and May 31, 2018, were identified, with the index date defined as the date of first ixekizumab or adalimumab claim.

Patients were required to be continuously enrolled for 12 months or more before the index date and followed for a minimum of 6 months until inpatient death, enrollment end, or end of the study. A total of 646 ixekizumab and 3668 adalimumab users were identified and followed for an average of 14 and 17 months, respectively. Inverse probability of treatment weights and multivariable regression modeling were used to address baseline cohort imbalances.

Before weighting, ixekizumab users were a mean (SD) 2.5 years older than adalimumab users (49.7 [2] vs 47.2 [12.9]). Besides being older, patients using ixekizumab had worse baseline health status as demonstrated by higher mean Deyo Charlson comorbidity and higher preperiod rates for comorbid conditions, including hypertension, hyperlipidemia, obesity, diabetes, and sleep apnea. In addition, they had a higher rate of preperiod biologic use, higher mean number of unique biologics, and higher rate of prior systemic treatment/targeted oral therapies than those taking adalimumab, indicating more severe illness. Total baseline all-cause and psoriasis-related health care costs were also higher for ixekizumab than for adalimumab.

Results showed that patients using ixekizumab were more likely to have lower risks of nonpersistence, treatment discontinuation, and treatment switching than patients using adalimumab.

Compared with adalimumab, ixekizumab was associated with a:

• 19% lower risk of nonpersistence (HR, 0.81; 95% CI, 0.69-0.95)
• 26% lower risk of discontinuation (HR, 95% CI, 0.62-0.88)
• 28% lower risk of switching (HR, 95% CI; 0.57-0.91)

Treatment adherence was assessed by medication possession ratio (MPR) as the primary definition and proportion of days covered (PDC) as the secondary definition. Although patients using ixekizumab had higher odds of MPR ≥ 80% compared with adalimumab, they had similar odds by proportion of days covered.

The authors said their results are consistent with previous studies, but that there are several limitations. Treatment adherence findings from this study should be considered as inconclusive since those on ixekizumab had a shorter mean length of follow-up than patients on adalimumab. The use of a logistic regression model did not account for variable length follow-up when looking at adherence. Future analysis using fixed-length follow-up is required to evaluate these findings. In addition, psoriasis severity was not measurable from claims data, which is why prior biologic use and the number of biologics tried was used as a proxy.

Reference

Blauvelt A, Shi N, Burge R, et al. Comparison of real-world treatment patterns among psoriasis patients treated with ixekizumab or adalimumab. Patient Prefer Adherence. 2020;14:517-527. doi:10.2147/PPA.S233993