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.