Background/Purpose:

Biologics (bDMARDs) have been shown to control disease progression in RA however there is still no cure for the disease and in many cases long-term use of these agents is required. Their cost and toxicity can be problematic over time and immunogenicity may cause their efficacy to diminish.

The aim of our research is to better understand long-term bDMARD survival to guide disease strategies and maximise patient outcomes.

Methods:

We used data collected as part of an online treatment survey conducted among a panel of 288 US rheumatologists between July 2011 and December 2014. We analysed a total of 6,113 patient forms and focused our research on 4,557 bDMARD patients with complete treatment information and analysed their current DAS, joint count and perceived disease severity to assess their response to therapy over time. A discriminant analysis was also performed to understand the relationship between four different groups of patients (based on their time on a bDMARD) and a number of patient characteristics to understand their associated with sustained response to bDMARDs.

Results:

The 1^st stage of our analysis showed that on average patients spent 29.5 months on their bDMARD (21.3 for switch patients). We observed differences in the mean drug survival of bDMARDs: 36.1 months for etanercept, 28.2 for adalimumab, 42.2 for infliximab, 23.1 for rituximab, 21.7 for abatacept, 11.9 for tocilizumab, 16.6 for certolizumab pegol and 15.1 for golimumab. The reported drug survival rates at 1, 2, 3, 4 and 5 years were 60.8%, 40.2%, 27.5%, 19.7% and 14.0% respectively. These results matched  the primary reasons given for switching bDMARD. Lack of long-term efficacy (> 6 months) was the most common reason (36.0%) followed by lack of initial response defined as ≤ 6 months (14.6%). Safety/tolerability issues were only chosen as a primary reason for switching in 10.9% of cases and immunogenicity was reported for 0.9% of patients.

We saw little significant difference between patients based on their length of time on treatment. Patients on bDMARDs for ≤ 12 months were significantly more likely to be aged below 24 years (p<0.05) while those who had been treated for > 12 months were more likely to be aged > 60. The latter were also significantly more likely to be retired. However, patients treated for > 6 months were more likely to be considered to have mild RA by their Dr and while patients treated for > 12 months had higher mean DAS they typically had lower mean joint counts.

The discriminate function showed a significant association between groups and the patient variables, accounting for 51.1% of between group variability. Closer analysis of the structure matrix showed only 2 significant associations, time since 1st ever bDMARD initiation (.832) and time since diagnosis (.712). The cross validated classification showed that 60.7% of cases were correctly classified.

Conclusion:

Our research emphasizes the fact that long-term response to bDMARDs varies considerably by patient and by drug. Lack of long-term efficacy is the most common reason for switching away from a bDMARD but immunogenicity is chosen in <3% of all cases (total reasons). More research is needed to better understand how to ensure sustained response with bDMARDs and optimise patient outcomes.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/long-term-use-of-biological-therapy-and-discontinuation-rates-in-rheumatoid-arthritis-real-world-patient-data/