Background/Purpose: Limited data are available about infliximab(IFX) dose escalation. This analysis examines the frequency of dose escalation among IFX patients using data from the US CORRONA RA registry and describes the characteristics of patients who dose escalate vs those who do not.

Methods: RA patients initiating IFX at a dose of ≤5 mg/kg on or after 6/1/2009 with at least 1 follow-up visit with dose information were eligible for analysis. Subgroup analysis was performed among patients with follow-up at 1yr to compare characteristics between those who dose escalated vs those who did not. Dose escalation was defined as an increase of >1mg/kg in dose and/or a decrease in the frequency of dosing by at least 1 wk (e.g. q 8 wks to q7 wks). Censoring occurred if patients switched to another biologic or left the registry. Descriptive statistics were used to compare baseline characteristics of infliximab patients stratified by number of biologics, and also comparing those who dose escalated vs those who did not within the 1^styr after initiating therapy.

Results: A total of 716 patients initiated IFX after June 2009. Common characteristics included mean age (61yrs), women (78%), mean weight (83kg), RF + (70%) and CCP+ (67%), baseline CDAI (22.5), and insurance status (Medicare 46%, Medicaid 6%). Differences between those who initiated IFX as their 1^st, 2^nd, or 3^rdbiologic included RA duration (7.0, 9.6, 11.0 yrs, respectively, p < 0.001), college education (50, 61, 66%, respectively, p = 0.002), number of prior DMARDs (1.6, 1.8, 2.0; p < 0.001), proportion receiving monotherapy (12, 15, 26%), and prednisone use (31, 29, 35%).

Over 3yrs follow-up, the proportions of patients escalating IFX significantly differed, ranging from a low of 21% at 1 yr for patients using IFX as 1^st line to a high of 81% at 3yrs for patients using it as 3^rd line (Table, p = 0.0024 for between-group differences). In patients with follow-up data at 12mo (n=608), there were some baseline characteristics associated with dose escalating vs not in the 1^styr of therapy including shorter RA duration(p = 0.03), greater number of prior biologics (p=0.04), monotherapy (p = 0.03), greater prednisone use (p=0.01), and higher CDAI (p=0.04) and related disease activity measures.

Conclusion: Dose escalation of IFX is relatively frequent over time. Patients with more severe RA undergo dose escalation more commonly than those with less severe disease. Understanding long term benefits and persistence and related factors following dose escalation may help optimize dose escalation as a treatment strategy compared to switching.

Table: proportion of patients increasing infliximab dose over time according to its use as a first, second, or third line biologic agent

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/an-examination-of-dose-escalation-among-remicade-infliximab-users-in-a-us-ra-registry/