Rheumatoid arthritis patients taking tumor necrosis factor inhibitors switch agents often, resulting in low 2-year continuation rates for these agents, despite the fact that no large, controlled studies have been done on the effects of frequent switching.
“Increased expectations on the part of the patient or the physician could play a role in creating impatience when immediate results are not seen” with given anti-TNF inhibitors, wrote Dr. Yusuf Yazici from the New York University Hospital for Joint Diseases, and colleagues.
And although much of the existing literature does support switching to another anti-TNF agent after initial failure, “these results have been reported mostly in small, short-term studies that focus on efficacy outcomes, not TNF inhibitor survival in the 'real world,'” he added.
In a study to assess anti-TNF treatment patterns, Dr. Yazici and colleagues looked at insurance claims data from 90 managed care organizations on 50 million patients in the United States. They analyzed data on all patients with RA who initiated anti-TNF therapy between Jan. 1, 2000, and July 1, 2005. A subsidiary cohort of the 6,070 patients who started an anti-TNF agent between 2003 and 2005 was also analyzed to assess use of adalimumab, which was not commercially available until 2003.
Patients on infliximab had the highest percentage of continuation on the drug in both cohorts. However, at 2 years, this figure was only 50%.
Furthermore, 40% of patients starting on infliximab needed one or more dose escalation over the study period, which has “important implications, given the drugs and administration costs associated with more medication use,” wrote the authors (J. Rheumatol. 2009 March 30 [doi:10.3899/jrheum.080592]).
Additionally, despite the relatively high continuation rate seen with infliximab, the authors found that etanercept was the most commonly prescribed initial anti-TNF agent, used by about 50% of patients in both cohorts who were starting anti-TNF therapy for the first time. However, at 2 years in both cohorts, only about 20% of the initial etanercept patients remained on the drug.
In the subcohort, adalimumab was the initial drug started by 1,365 patients (23% of the cohort); the continuation rates closely mirrored those seen with etanercept.
Dr. Yazici and his colleagues speculated that the flexibility of infliximab scheduling and dosing, and the ability of a majority of patients to increase their dose, may explain why infliximab had higher continuation rates than did the two other agents. Additionally, the authors postulated that because infliximab is an agent that is given by infusion and thus requires regular follow-up, “seeing a physician regularly may encourage a patient to remain” on the regimen.
They recommend that other agents now on the market, like abatacept and rituximab, also be investigated in a real world setting.
“TNF inhibitor use patterns are changing with time, with more frequent changes and shorter duration of treatment before the change,” wrote the authors. “Further research needs to be conducted to determine if those tends remain constant with the availability of new biologic treatment options, and how these newer treatments influence the treatment algorithm.”
Dr. Yazici has served as a consultant and/or speaker for Bristol-Myers Squibb Co., Celgene Corp., Centocor Inc., Genentech Inc., Hoffmann-La Roche Inc., and UCB SA. One of the authors on the current study is an employee of Bristol-Myers Squibb.