Real-World Biologic Adherence, Persistence, and Monotherapy Comparisons in US Patients with Psoriasis: Results from IBM MarketScan^® Databases

This is a retrospective cohort analysis aiming to characterize patients with psoriasis treated with biologics including IXE, SEC, UST, ADA, and ETN using IBM Marketscan^® Research Databases (The Commercial and Medicare Supplemental Database, supplemented with more recent data by the Early View Database). IBM Marketscan^® Research Databases are collections of de-identified claims data for commercially insured people in the US capturing patient-level data on demographics, healthcare resource utilization, expenditures, and enrollment across inpatient, outpatient, prescription drug, and carve-out services. No institutional review board approval was required as the statistical analyses utilized a de-identified secondary data source.

Selected patients received newly initiated biologics (IXE, SEC, UST, ADA, or ETN) between July 1, 2016, and July 1, 2018, from IBM MarketScan^® Databases. The index date was set at the date of the first claim of the index biologic. The index biologic was the first biologic claimed during the study window. Patients were assigned to the IXE, SEC, UST, ADA, or ETN cohort based on the medication claim on the index date. Patients were additionally required to have continuous enrollment with medical and pharmacy benefits for at least 6 months before biologic initiation (“pre-index”) and a minimum of 12 months after the index date (“post-index”). Patients included in the cohort had at least one inpatient or two outpatient psoriasis diagnosis claims (at least 21 days apart) (ICD-9-CM codes 696.1 × or ICD-10 codes L40.0–L40.4 or L40.8). At least one of the PsO diagnosis claims occurred pre-index. Patients had to be at least 18 years of age at their index date. Patients diagnosed with other autoimmune diseases including ankylosing spondylitis, rheumatoid arthritis, Crohn’s disease, or ulcerative colitis during the pre-index period were excluded to avoid inclusion of patients taking biologics for other disease than psoriasis.

Patient demographic and clinical characteristics along with treatment patterns were reported for each index biologic at baseline.

Adherence to each index biologic was measured by the proportion of days covered (PDC), defined by the sum of the number of days covered on the index medication divided by the follow-up days; overlapping days between claims were truncated to avoid potential double-counting. Patients were deemed to be highly adherent if they had PDC ≥ 80%. Monotherapy was defined as days of the index medication without concomitant systemic, phototherapy, or other biologics. PDCs of monotherapy were also reported for each index biologic. PDC of concomitant medication, defined as the use of any systemic medications including other biologics and phototherapy during the post-period, was reported.

Persistence was measured by calculating the time from index date to treatment interruption. Patients were persistent if they received continuous treatment with the same study drug without a prescription gap of > 60 days (between a prescription’s last day of supply and date of next refill) from the index date to the end of continuous enrollment or the end of the study period.

The patient populations for this data analysis were [1] those with prior 6-month eligibility (pre-index) and post-index 1-year follow-up and [2] prior 6-month eligibility (pre-index) and post-index > 1-year follow-up. Inverse probability of treatment weighting (IPTW) was applied before comparison to address cohort imbalances in patient demographic characteristics (index age, gender, geographic region, health plan type), clinical characteristics in the baseline period (Deyo-Charlson comorbidity index and comorbid conditions, including anxiety, cerebrovascular disease, depression, diabetes, hyperlipidemia, multiple sclerosis, obesity), baseline biologic/systemic/topical/phototherapy use, and prior 6-month total health care costs. The PDC and percent of patients achieving ≥ 80% PDC on adherence, monotherapy, and concomitant medication were compared between treatments using weighted t-tests and weighted logistic regression models.

Kaplan-Meier curves were used to estimate the observed time to the first medication gap of > 60 days, and weighted Cox proportional hazards model was used to obtain the hazard ratio (HR) of IXE versus other biologics on medication discontinuation. Sensitivity analyses on adherence and persistence were also conducted with further adjustments in the respective tests using the same variables as those for IPTW.

Patient demographic and baseline characteristics are provided in Table 1. A total of 7797 patients met the inclusion criteria, of which 742 initiated IXE, 3592 ADA, 524 ETN, 1027 SEC, and 1912 UST. Mean age across biologic treatment cohorts ranged from 46.2 years (ADA) to 49.3 years (IXE). Percentage of females across the biologics ranged from 44.2% (IXE) to 48.5% (ETN). Most biologic users resided in the South (46.7%–51.1%) and were covered by commercial insurance (92.7%–97.0%). A higher proportion of patients receiving IXE had previous biologic therapies (50.3%) versus other biologics (ADA: 9.1%, ETN: 10.9%, SEC: 33.9%, UST: 19.7%).

Among patients with 1-year follow-up, the PDC on monotherapy was significantly (p < 0.001) higher in patients taking IXE compared with all biologics combined (0.66 vs. 0.59) and compared with individual biologics: ADA (0.66 vs. 0.61), ETN (0.66 vs. 0.48), and UST (0.66 vs. 0.56) and with SEC (0.66 vs. 0.63, p < 0.05) as well (Table 2). Similar results were observed for patients with 1–3 years of follow-up. Sensitivity analyses with further model adjustments after IPTW confirmed the findings on adherence.

At 1-year post follow-up, concomitant medication use was significantly shorter in patients treated with IXE compared with all biologics combined and when compared with ADA and ETN but not with SEC and UST (Table 2). However, as the follow-up extended from 1 to 3 years, IXE showed significantly shorter concomitant medication use than all other biologics combined and compared to ADA, ETN, SEC, and UST, respectively (Table 2).