2.2. Inclusion and exclusion criteria
Studies that qualify must satisfy each of the following criteria for inclusion: (1) The study’s design was a case-control study; (2) It examined the association between pSS and TNFSF13B gene polymorphisms; (3) It provided information on the frequencies of TNFSF13B genotypes and alleles for both pSS patients and health controls; and (4) Its subjects were TNFSF13B gene positive. The following were the exclusion requirements: (1) duplicate data were found in the studies; (2) completely irrelevant to the theme of this meta-analysis; (3) the research was a family study; (4) the research direction was not consistent with this article; (5) reviews; (6) abstracts only; (7) the recording method of phenotype for TNFSF13B gene was different from this paper; (8) without health controls; and (9) inapplicable statistical data.