Timely Use of Tumor Necrosis Factor Inhibitors Effectively Manages Psoriatic Arthritis

A new analysis of treatment costs and trial outcomes concludes that immediate use of tumor necrosis factor inhibitors (TNFis) is a cost-effective strategy for managing psoriatic arthritis patients with both skin and joint involvement but not for managing those patients with joint disease alone.

Investigators developed a Markov model to estimate the costs and outcomes of using different treatment strategies on psoriatic arthritis patients. They then plugged trial data and public information about treatment prices into their model and tabulated results.

Patients in the model received either 1 of 4 TNF-inhibiting medications — adalimumab, etanercept, infliximab, or golimumab — or apremilast as their initial treatment. Those who would not have achieved an American College of Rheumatology 20 (ACR20) response (defined as a 20% reduction in joint-related disease symptoms) in the first 12 weeks of treatment then began TNFi treatment (if they started on apremilast) or switched to a different TNFi.

The model also evaluated patients who also had moderate-to-severe psoriasis that affected at least 3% of their total body surface to see how frequently different treatment strategies would achieve a psoriasis area and severity index 75 (PASI75) response (which is defined as a 75% reduction in psoriasis symptoms).

The study team used the model to estimate response rates after 1 year of treatment, the number of patients needed to treat per responder, the per-patient cost of both immediate and delayed TNFi therapy and the per-responder cost of both immediate and delayed TNFi therapy.

The model predicted that delaying TNFi usage 12 weeks to see which patients would respond to apremilast alone (rather than using a TNFi from the outset) would result in significantly worse outcomes for patients and that the effects of that initial choice would linger for at least a year.

Compared to the 12-week delay, immediate TNFi usage would produce higher ACR20 response rates (70% vs. 60%) and, therefore, lower patients-needed-to-treat figures (1.42 vs 1.68). Among psoriatic arthritis patients who also had psoriasis, immediate TNFi treatment would produce, at the 1-year mark, higher ACR20+PASI75 response rates (41% vs. 30%) and lower patients-needed-to-treat figures (2.44 vs. 3.33).

The superior outcomes of immediate treatment would come at a significant financial cost, however. Immediate TNFi usage would push the typical 1-year treatment cost among all patients from $31,513 to $39,754 and the typical 1-year treatment cost among psoriatic arthritis and psoriasis patients from $33,510 to $41,437.

Immediate TNFi usage would also create higher treatment costs per ACR20 responder for the total patient pool ($56,492 vs $52,835). Among comorbid patients, however, immediate TNFi treatment would be associated with a lower cost per ACR20+PASI75 responder ($100,954 vs $111,686).

“In this economic model,” the investigators wrote in an abstract they presented at the 74^th annual meeting of the American Academy of Dermatology, “timely use of TNFis was a more effective strategy for managing PsA and was a more cost-effective strategy for managing patients with both joint and skin involvement.

The study model used the different TNFi medications in a way that reflects their existing market share rather than any strategy for reducing costs, but previous research shows that payers face significantly different costs for the different medications.

“Across all indications, the annual TNF-blocker cost per treated patient was lowest for etanercept, followed by adalimumab and then infliximab, respectively: overall ($17,767, $19,272, and $24,273); new patients ($17,270, $17,959, and $21,482); and continuing patients ($18,203, $20,453, and $25,468),” wrote the authors of a 2013 study that appeared in the Journal of Managed Care Pharmacy.