Psoriasis is a chronic immune-mediated inflammatory skin disease that occurs in 2.5-3.5% of the general population. Infliximab (INF), a TNF-α inhibitor biologic agent, is a long-standing efficacious treatment for psoriasis; however, not all patients sustain a long-term response (LTR) because of a number of factors including antibody production. There is a paucity of studies assessing infliximab efficacy over a period ≥ 5 years.
A retrospective cohort chart review of our clinic patients who had undergone ≥ 5 years of treatment with infliximab for chronic plaque psoriasis was performed. The following variables were recorded and analyzed with the Fisher exact test: age, sex, body mass index ([BMI]; normal weight [NW], overweight [OW], obese [OB]), changes in infliximab strength (dose or frequency), concomitant systemic therapy, and side effects. Clinical improvement was assessed by comparing the total body surface area (tBSA) affected by psoriasis before and after treatment.
There was a significant difference in likelihood of achieving LTR between the NW, OW and OB groups (p = 0.044). Non-normal-weight patients (OW + OB) were significantly more likely to achieve and sustain LTR than NW patients (OR 9.07, p = 0.020). There were no other significant associations for the other evaluated variables.
Patients who began treatment with infliximab before 2009 (prior to the use of the clinic's electronic medical record) were excluded. The Psoriasis Area and Severity Index (PASI) was not available for this study.
Surprisingly, patients who are overweight or obese are more likely to obtain long-term clinical benefit in their psoriasis symptoms with infliximab therapy than patients who are normal weight.