Background/Purpose: To explore differences in response to low dosage (2.3mg/kg) regimen of infliximab with possible escalating dosage in comparison to standard dosage of etanercept and adalimumab over time in patients with psoriatic arthritis (PsA).

Methods: Patients with PsA who were all biologically naïve and initiating anti-TNF-α therapy were selected from the ICEBIO registry which is based on the DANBIO IT platform. Demographics and clinical differences at baseline, including DAS-28CRP, were compared in four treatment groups: 1) Those who responded to low dosage of infliximab (< 4 mg/kg), 2) those who needed to increase the dosage of infliximab above 4 mg/kg, and those who received a standard dosage of 3) etanercept or 4) adalimumab. Follow-up data at 26 ± 6 and 52 ± 6 weeks and on the last visit (at least 13 weeks after the initiation of the treatment) were also compared. The Kruskal-Wallis rank sum test was used for comparison of the groups and the Wilcoxon test was used to compare the two infliximab dosage regimens.

Results: 185 patients, 113 women and 72 men, were identified; 84 patients received infliximab, 66 etanercept and 35 adalinmumab. Only 19% of the patients (16/84) treated with infliximab needed to escalate their dosage to exceed 4 mg/kg; thus those still on a low dosage regimen had a mean dosage of infliximab 2.9 mg/kg, but those who had escalated their dosage had a mean dosage of 4.5 mg/kg, i.e. still under the recommended 5 mg/kg. At baseline those who continued low dosage infliximab had a shorter disease duration (8 vs. 10 years), while those who needed to increase their dosage of infliximab had a higher CRP (10.4 vs. 17.2 g/L), but neither value reached significant differences. No significant differences were observed at baseline in respect to numbers of swollen or tender joints, HAQ, VAS pain, VAS fatigue or DAS28-CRP values. A similar treatment response was observed in all four treatment groups on follow-up.

Conclusion: In respect to treatment effects a low dosage of infliximab, with starting dosage of 2.3mg/kg with possible escalating dosage, is acceptable for the majority of psoriatic arthritis patients who are in need of biological treatment. This “low dosage treatment regimen” with infliximab significantly reduces the burden of drug cost for the society.

*ICEBIO: Erlendsson K, Geirsson AJ, Grondal G, Jonsson H, Jonsdottir T, Ludviksson BR, Steinsson K, Tomasson G, Valtysdottir S, Vikingsson A.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/low-dosage-with-escalating-dosage-of-infliximab-in-psoriatic-arthritis-gives-the-same-treatment-results-as-standard-dosage-of-adalimumab-or-etanercept-results-from-the-nationwide-registry-icebio/