The effect of weight reduction on treatment outcomes in obese patients with psoriasis on biologic therapy: a randomized controlled prospective trial

Background: Obesity has long been associated with psoriasis and it is considered to be an independent risk factor for chronic heart diseases in these patients. Recently, some of the biologic drugs used for psoriasis have been reported to cause increase in body weight. It is currently not clear if this increased body weight seen in psoriasis patients on biologics leads to decrease in there efficacy or vice versa. We carried out this study to see if reduction in body weight leads to increased efficacy of biologics in obese psoriasis patients. Objective: To evaluate the effect of weight reduction by dietary control on treatment efficacy of biologics in obese patients as indicated by the Psoriasis Area and Severity Index (PASI) score. Methods: Obese patients with psoriasis receiving biologic therapy, satisfying the inclusion criterion, were randomized in a 1: 1 ratio to receive low-calorie diet versus normal diet (control group). We included 262 patients with moderate to severe, stable plaque psoriasis with a PASI score 20: 50 on anti TNF-alpha biologic therapy (infliximab, etanercept, ustekinumab and adalimumab). The patients in the dietary intervention group were given a low calorie diet (<= 1000 kcal per day) for 8 weeks to induce weight loss. The treatment outcome was assessed using PASI. The PASI scores were assessed at baseline and every 4 weeks up to week 24. Results: There were no significant differences in age, sex distribution, body weight, body mass index, waist circumference, psoriasis duration, or PASI score between the two studied groups at base line. At week 24, the mean (+/- SD) weight loss was 12.9 +/- 1.2 kg in the diet intervention group, and -1.5 +/- 0.5 kg in the control group. The average improvement in mean PASI score was 84% for the diet group, and 69% for the control group. PASI 75 was achieved by 85.9% in the diet group, and 59.3% in the control group (p < 0.001). The mean (+/- SD) body surface area values at week 24 were 3.3 +/- 4.4% and 8.1 +/- 6.9% in the diet group and control group. Conclusions: Body weight reduction in obese patients on biologics may increase the efficacy of the drug.