Canadian Study Finds High Adherence to Anti-TNF Agents in Inflammatory Diseases

Anti—tumor necrosis factor (TNF) therapies are the most widely used biologics in rheumatology in Canada, due to many years of clinical experience and provincial reimbursement criteria. A large Canadian study of patients with inflammatory diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PA), and ankylosing spondylitis (AS), reports that a high overall rate of adherence to subcutaneous anti-TNFs (76% of patients).

In addition, the data show that patients taking golimumab (Simponi) had the highest adherence compared with other subcutaneous anti-TNFs: adalimumab (Humira), etanercept (Enbrel), and certolizumab pegol (Cimzia). The study also confirmed previous research showing that patients have better adherence to medications with longer versus shorter dosing intervals, and supported the inverse relationship between dosing frequency and adherence reported in various studies with different medication classes.

The study, published in the July 2017 issue of BMJ Open, was supported by Janssen, Canada, the manufacturer of golimumab. The finding is important because nonadherence to therapy is an important, modifiable factor that may compromise patient outcomes, said lead author Peter Bhoi, of Janssen Inc. Dosing intervals for subcutaneous anti-TNFs were evaluated in order to assess the proportion of patients whose treatment needed to be intensified (by shortening the dosing interval) during the course of a 2-year follow up. “We found that shortening of the dosing interval was observed in all the [subcutaneous anti-TNF] cohorts, and that the proportions of patients were comparable between the 4 drugs,” the study’s authors said. “To the best of our knowledge, this it he first detailed report on shortening of the dosing interval across different [subcutaneous anti-TNFs].”

The researchers used prescribing data from January 1, 2010, to June 30, 2012, and followed patients for 24 months through June 30, 2014. Patients included in the study were adults newly prescribed a subcutaneous anti-TNF with at least 3 prescriptions, and retained on therapy for at least 24 months. The study included 4035 patients, with 683 (16.9%) receiving golimumab; 1400 (34.7%) receiving adalimumab; 1764 (43.7%) receiving etanercept; and 187 (4.6%) receiving certolizumab pegol. The study included over half of the overall Canadian population of patients with inflammatory rheumatic diseases.

The researchers report that the proportion of adherent patients in the golimumab cohort (n = 595, 87%; P < .0001) was greater than that of adalimumab- (n = 1044, 75%), etanercept- (n = 1285, 73%), and certolizumab pegol-treated patients (n = 132, 71%).

In addition, the number of patients receiving a biologic at a shorter dosing interval was similar among cohorts:

• 5% for those receiving golimumab (≤26 days)
• 6% for those receiving adalimumab (≤12 days)
• 12% for those receiving etanercept (≤6 days)
• 4% in those receiving certolizumab pegol (≤12 days)

In conclusion, this real-life study evaluating adherence to anti-TNFs in inflammatory diseases, using data from the Canadian administrative databases, demonstrates considerably high adherence rates. The finding that golimumab has better adherence compared with the other subcutaneous anti-TNFs could be explained, in part, by its simpler, less frequent dosing regimen. Further studies are needed to investigate the reasons for the difference in adherence between golimumab and other subcutaneous anti-TNFs, and to evaluate the impact of this improved adherence on clinical and health-economic outcomes.