Induction immunosuppression after heart transplantation: monoclonal vs. polyclonal antithymoglobulins. Is there a difference?

Induction immunosuppression after heart transplantation is believed to reduce the risk of acute graft rejection. While monoclonal and polyclonal antithymoglobulins are considered the optimal induction agents, controversy remains regarding their relative superiority. This article presents a systematic review of the literature and a meta-analysis in order to assess the relative benefits and side-effects of monoclonal vs. polyclonal antithymoglobulins as induction immunosuppression agents. Pooled analysis demonstrated a small but statistically insignificant difference in the average time to first rejection between the groups (6.7+/-15.5 days, P=0.39). No statistically significant differences in the proportion of patients who developed rejection or infection episodes at 6 months were observed (Relative Risk 0.97, P=0.82 and Relative Risk 0.85, P=0.14, respectively). In addition, no statistically significant difference in survival was found between the groups at 6 months (Relative Risk 0.98, P=0.58). A greater number of drug related side-effects was observed, however, in the monoclonal group, including episodes of acute pulmonary edema and hypotension. In conclusion, this review revealed no statistically significant differences in rejection, infection, or survival rates between the monoclonal and polyclonal groups. The increased rate of side-effects with monoclonal antibodies might suggest a superiority of polyclonal over monoclonal antibodies.