Abstract: Objective Meta-analysis was performed to analysis positive rate and distribution characteristics of unexpected antibodies in Chinese blood donors to provide data for judging whether blood donors in China needs to carry out unexpected antibodies detection. Methods We searched PubMed,CNKI,WanFang Data,VIP,and CBM databases and entered specific search terms for relevant literature on unexpected antibodies in Chinese donors from inception to December 2019. According to inclusion and exclusion criteria,five researchers independently screened literature, extracted relevant data and assessed the methodological quality. The R3.6.2 software was used to perform meta-analysis. Results A total of 38 cross-sectional studies were included. Meta-analysis results showed that total antibody positive rate of donors in China was 0.20% [95%CI（0.15%,0.25%）]. The antibody positive rate of male donors was 0.13% [95%CI（0.10%,0.16%）], and that of female donors was 0.31% [95%CI（0.26%,0.37%）]. The antibody positive rate of female donors was higher than that of male donors. There was no statistically significant difference. Among the positive antibodies, the most abundant antibody isotype was IgM,accounting for 59.78%[95%CI（50.01%,69.54%）]. IgG antibody accounted for 31.33% [95%CI （23.44%, 39.22%）] of the total positive antibodies and IgG antibodies were more common in females. Based on the results of antibody identification, the positive rate of antibody in each blood group system was different： Rh system accounting for about 31.64%[95%CI（25.25%,38.03%）] （about 99.61% were IgG antibodies,mainly anti-D and anti-E）,MNS system accounting for about 23.73%[95%CI（18.80%,28.65%）] （about 88.74% were IgG antibodies,mainly anti-M）,Lewis system accounting for about 8.18%[95%CI（5.71%,10.66%）] （mainly IgG antibodies,mainly anti-Le^a）,P system accounting for about 4.54%[95%CI（2.58%,6.51%）] （mainly IgM antibody,mainly anti-P）,other systems （including non-specific antibody and autoantibody） accounting for 22.78%[95%CI（14.09%,31,46%）] （mainly IgM antibody）, Kell system accounting for about 0.05%[95%CI（0,0.46%）], Duffy system accounting for about 0.05%[95%CI（0,0.46%）] （mainly IgG antibody, mainly anti-Fy^a）,Kidd system accounting for about 0.01%[95%CI（0,0.42%）] （all anti-Jka）, and the Diego system accounting for about 0.01%[95%CI（0,0.4%）] （all anti-Di^a）. Antibody frequency ranking： anti-M>anti -D>anti -E>anti -Le^a>anti -P>anti -Le^b>anti -N>anti -cE>anti -C>anti -Fy^a>anti -Jk^a>anti -Di^a. Conclusion It is necessary to bring the unexpected antibody screening test into routine project for blood donors. It will reduce experimental cost and benefit implementation of electronic cross-matching to develop special spectrum of blood donor screening cells aiming at most common unexpected antibodies present in blood donors.

Key words: China, Blood donors, Unexpected antibody, Meta-analysis