Although most biologic medications for patients with rheumatoid arthritis (RA) have recommended fixed dosing, actual biologic dosing may vary among real-world patients, since some patients can receive higher (high-dose outliers) or lower (low-dose outliers) doses than what is recommended in medication package inserts.
To describe the patterns of care for biologic-dosing outliers and nonoutliers in biologic-naive patients with RA.
This was a retrospective, longitudinal cohort study of patients with RA who were not pregnant and were aged ≥ 18 and < 90 years from an integrated health care delivery system. Patients were newly initiated on adalimumab (ADA), etanercept (ETN), or infliximab (IFX) as index biologic therapy between July 1, 2006, and February 28, 2014. Outlier status was defined as a patient having received at least 1 dose < 90% or > 110% of the approved dose in the package insert at any time during the study period. Baseline patient profiles, treatment exposures, and outcomes were collected during the 180 days before and up to 2 years after biologic initiation and compared across index biologic outlier groups. Patients were followed for at least 1 year, with a subanalysis of those patients who remained as members for 2 years.
This study included 434 RA patients with 1 year of follow-up and 372 RA patients with 2 years of follow-up. Overall, the vast majority of patients were female (≈75%) and had similar baseline characteristics. Approximately 10% of patients were outliers in both follow-up cohorts. ETN patients were least likely to become outliers, and ADA patients were most likely to become outliers. Of all outliers during the 1-year follow-up, patients were more likely to be a high-dose outlier (55%) than a low-dose outlier (45%). Median 1- and 2-year adjusted total biologic costs (based on wholesale acquisition costs) were higher for ADA and ETA nonoutliers than for IFX nonoutliers. Biologic persistence was highest for IFX patients. Charlson Comorbidity Index score, ETN and IFX index biologic, and treatment with a nonbiologic disease-modifying antirheumatic drug (DMARD) before biologic initiation were associated with becoming high- or low-dose outliers (c-statistic = 0.79).
Approximately 1 in 10 study patients with RA was identified as a biologic-dosing outlier. Dosing outliers did not appear to have better clinical outcomes compared with nonoutliers. Before initiating outlier biologic dosing, health care providers may better serve their RA patients by prescribing alternate DMARD therapy.
This study was sponsored by Janssen Scientific Affairs. It is the policy of Janssen Scientific Affairs to publish all sponsored studies unless they are exploratory studies or are determined a priori for internal use only (e.g., to inform business decisions). Meyer is an employee of Janssen Scientific Affairs and a stockholder in Johnson and Johnson, its parent company. Delate and Jenkins have nothing to disclose. Study concept and design were contributed by Delate and Meyer. Delate took the lead in data collection, along with Jenkins. All authors participated in data analysis. The manuscript was written primarily by Delate, along with Meyers and Jenkins, and was revised by Meyer, along with Delate and Jenkins.