Meta-analysis: The adjuvant role of thymopentin on immunological response to hepatitis B virus vaccine in end-stage renal disease

Background: It has been calculated that 30-40% of dialysis patients fail to produce antibodies to HBsAg antigen after vaccination towards hepatitis B virus. Several authors have reported on the benefit of thymopentin (TP5) as adjuvant to vaccine against hepatitis B virus in patients receiving regular dialysis. However, consistent information on this issue is still lacking. Aims: To evaluate efficacy and safety of thymopentin as adjuvant to hepatitis B vaccine in dialysis patients by performing a systematic review with a meta-analysis of clinical trials. Methods: We used the random effects model of DerSimonian and Laird, with heterogeneity and sensitivity analyses. Results: We identified 11 studies involving 272 unique patients with end-stage renal disease. Only prospective, controlled trials were included. Pooling of study results did not show a significant increase in seroresponse rate among study (thymopentin plus hepatitis B virus vaccine) vs. control (hepatitis B virus vaccine alone) patients; the pooled odds ratio of failure to respond to hepatitis B virus vaccine was 0.677 (95% confidence intervals: 0.285-1.605); no heterogeneity was found (P = 0.0001). Thymopentin significantly improved the seroresponse rate in the subgroup of trials based on greater thymopentin doses (OR: 0.184; 95% CI: 0.085-0.398). Conclusions: Our meta-analysis showed that thymopentin significantly improved the seroresponse rate towards hepatitis B vaccine only in dialysis patients treated with higher thymopentin doses. The limited number of patients precluded definitive conclusions.