According to the authors of a recent study, although monitoring of anti-drug antibodies (ADAbs) or serum concentrations of biologicals in rheumatoid arthritis treatments could explain efficacy loss, and help with choosing subsequent medication, such monitoring of tumor necrosis factor (TNF)-α blockers is not generally done on a routine basis in current clinical practices. They have, however, demonstrated the cost-benefits of routine monitoring of drug levels and ADAbs in clinical practice, which they report can in turn improve the decision-making process of using TNF-α blockers.
Finland-based researchers estimating the likelihoods of optimal and nonoptimal treatment decisions whether or not infliximab or adalimumab drug trough level and ADAbs are tested in rheumatoid arthritis gathered drug levels and ADAbs concentration data of 486 and 1137 samples from Finnish patients taking adalimumab and infliximab, respectively. The investigators also intended to model cost-effectiveness of performing routine monitoring of this sort
Among samples from patients who were treated with adalimumab and infliximab, drug levels were in the target range of 42.0% and 50.4%, and ADAbs were detected in approximately 20.0% and 13.5%, respectively. In patients with low adalimumab or infliximab drug levels, ADAbs were found in 52.3% and 41.3%, respectively. Monitoring data were then merged into probabilities for making optimal treatment decisions.
During 3 to 6 months, the researchers used a scenario with 100 hypothetical patients to model the economic impact of clinical decision-making. The model consisted of drug level and ADAbs cost-saving measurements combined and compared with the non-testing scenario when monitoring results affected treatment decisions of ≥2 to 5 of 100 patients (a proportion that is easily exceeded in real-life clinical practice).
According to the authors, ineffective treatment of 5 patients for 3 months or 2.5 patients for 6 months costs approximately $24,758. When only 2.5 to 5 of 100 patients were treated nonoptimally for 3 to 6 months, routine measurement of drug levels and ADAbs proved to be cost-saving compared with the non-testing scenario.
“Our study indicates that the probability of nonoptimal drug treatment decision is noteworthy among the Finnish patients using infliximab and adalimumab if the data on individual DLs and ADAbs are not available,” the study authors reported. “Even at very low probability of nonoptimal decision, the systematic measurement of DLs and ADAbs seems to be cost-saving.”
- Laine J, Jokiranta TS, Eklund KK, et al. Cost-effectiveness of routine measuring of serum drug concentrations and anti-drug antibodies in treatment of rheumatoid arthritis patients with TNF-α blockers. Biologics. 2016;10:67-73.