Exploring the safety and effectiveness of subcutaneous autologous serum therapy versus conventional intramuscular autologous serum therapy in chronic urticaria: An observer-blind, randomized, controlled study

Background: Autologous serum therapy aims to supplement the existing pharmacotherapy in chronic urticaria by decreasing the antihistamine pill-burden and maintaining symptom-free interval. Subcutaneous autologous serum therapy further modifies the amount of serum (2 mL to 1 mL) and gauge of a needle (24G to 31G) to improve compliance and facilitate ease of application. Objectives: To assess clinical effectiveness and safety of subcutaneous autologous serum therapy versus conventional intramuscular autologous serum therapy and to compare the quality of life in the two treatment arms. Methods: Institution-based, assessor-blind, prospective, randomized, parallel-group, active-controlled trial with 32 patients in each treatment arm and analyzed on a modified intention to treat principle. After baseline autologous serum skin test, autologous serum was injected as per randomization every week for 9 consecutive weeks. Results: Among the study population, conventional intramuscular autologous serum therapy and subcutaneous autologous serum therapy had a comparable duration of disease (P = 0.164, Mann-Whitney U test), autoreactive status (P = 0.796), urticaria total severity score (P = 0.637) and urticaria activity score summed up over 7 days (P = 0.982). Both urticaria activity score summed up over 7 days and total severity score along with antihistamine pill-burden reduced significantly (P < 0.001, Friedman's analysis of variance) in both subcutaneous autologous serum therapy and conventional intramuscular autologous serum therapy from first follow-up onwards (P < 0.05, Post hoc Dunn's test). Significant improvement was noted in patient's as well as physician's global assessment of disease activity improvement scale (P < 0.001, Friedman's analysis of variance). Intergroup analysis showed that there was no significant difference in urticaria activity score summed up over 7 days either at baseline (P = 0.982, Mann-Whitney U test) or at study end (P = 0.398, Mann-Whitney U test). Similar comparable results were found in the total severity score at the end of the study (P = 0.345, Mann-Whitney U test). Dermatology life quality index showed marked improvement with both types of treatment (P < 0.0001, Wilcoxon test), and the intergroup comparison showed comparable dermatology life quality index values (P = 0.994, Mann-Whitney U test). The pain score at the injection site was more with conventional intramuscular autologous serum therapy than subcutaneous autologous serum therapy (P = 0.0115, Mann-Whitney test). Younger age and lower baseline total severity scores were associated with a better therapeutic response. Baseline urticaria activity score added up over a period of 7 days and total severity scores and the diameter of lesions showed a positive correlation with response pattern. Limitation: Basophil histamine release assay not done. Logistics could not support follow-up beyond the end of treatment. Conclusion: Subcutaneous autologous serum therapy is not inferior to conventional intramuscular autologous serum therapy with the additional advantage of less pain and operational feasibility.