Background: Previous studies have evaluated the associations between the cholesteryl ester transfer protein (CETP) TaqIB polymorphism (rs708272), the risk of developing composite ischemic cardiovascular disease (CVD) and the concentration of high-density lipoprotein cholesterol (HDL-C), but results remain controversial. The objective of this study was to investigate whether a relationship exists between these factors. Methods: We conducted a meta-analysis of available studies to clarify the associations of the CETP TaqIB polymorphism with HDL-C concentration and the composite ischemic CVD risk in both Asians and Caucasians. All statistical analyses were done with Stata 12.0. Results: Through utilization of the Cochrane Library, Embase, PubMed, Web of Science, Springer, China Science and Technology Journal Database, China National Knowledge Infrastructure, Google Scholar, and Baidu Library, a total of 45 studies from 44 papers with 20,866 cases and 21,298 controls were combined showing a significant association between the CETP TaqIB variant and composite ischemic CVD risk. Carriers of allele TaqIB-B1 were found to have a higher risk of composite ischemic CVD than non-carriers: OR = 1.15, 95% CI = 1.09–1.21, p < 0.001. Meanwhile, 28 studies with 23,959 subjects were included in the association between the CETP TaqIB polymorphism and the concentration of HDL-C. Results suggested that carriers of the B1B1 genotype had lower concentrations of HDL-C than those of the B2B2 genotype: SMD = 0.50, 95% CI = 0.36–0.65, p < 0.001. Conclusions: The synthesis of available evidence demonstrates that the CETP TaqIB polymorphism protects against composite ischemic CVD risk and is associated with a higher HDL-C concentration in both Asians and Caucasians.

Objective: This study aimed to detect the association between polymorphisms and haplotype in the ATP-binding cassette transporter A1 (ABCA1) gene and overweight/obese Uyghur patients in China. Methods: A total of 259 overweight/obese patients and 276 normal weight subjects, which were randomly selected from among 3049 adult Uyghurs, were matched for age. We genotyped ABCA1 single nucleotide polymorphisms of rs2515602, rs3890182, rs2275542, rs2230806, rs1800976, and rs4149313. Results: (1) The genotypic and allelic frequencies of rs2515602 and rs4149313 differed between the control group and case group. The genotypic frequency of rs2275542 also differed between the control group and case group (p < 0.05); (2) rs2515602, rs2230806, and rs4149313 polymorphisms were significantly related to risk of overweight/obese; (3) a significant linkage disequilibrium (LD) was observed between the ABCA1 gene rs2275542 with rs3890182 and rs2515602 with rs4149313. (4) the C-C-C-A-G-G, T-C-G-A-G-G, and T-T-G-G-G-A haplotypes were significant in normal weight and overweight/obese subjects (p < 0.05); (5) the levels of HDL-C (rs2515602, rs2275542, rs4149313) in normal weight subjects were different among the genotypes (p < 0.05); the levels of TC, LDL-C and TG (rs1800976) in overweight/obese subjects were different among the genotypes (p < 0.05). Conclusions: The rs2515602, rs4149313, and rs2275542 polymorphisms were associated with overweight/obese conditions among Uyghurs. Strong LD was noted between rs2275542 with rs3890182 and rs2515602 with rs4149313. The C-C-C-A-G-G and T-C-G-A-G-G haplotypes may serve as risk factors of overweight/obesity among Uyghurs. The T-T-G-G-G-A haplotype may serve as a protective factor of overweight/obesity among Uyghurs. Rs2515602, rs2275542, rs4149313, and rs1800976 polymorphisms in the ABCA1 gene may influence lipid profiles.

Objective: To detect the interactions between six functional polymorphisms in ABCA1 and obesity in Kazakhs with low HDL-C levels. Methods: A total of 204 patients with low HDL-C and 207 health control subjects, which were randomly selected from among 5692 adult Kazakhs, were matched for age and sex. We genotyped ABCA1 single nucleotide polymorphisms of rs2515602, rs3890182, rs2275542, rs2230806, rs1800976, and rs4149313. Results: (1) The genotypic and allelic frequencies of rs2515602, rs2230806 and rs4149313 were different between normal HDL-C and low HDL-C subjects, the genotypic frequency of rs2275542 was also different between normal HDL-C and low HDL-C subjects (p < 0.05); (2) the level of HDL-C (rs2515602 and rs2275542) in normal HDL-C subjects were different among the genotypes (p < 0.05); the levels of TC, LDL-C (rs2515602, rs4149313); TG (rs2515602, rs1800976, rs4149313) in low HDL-C patients were different among the genotypes (p < 0.05); (3) interactions between the rs3890182, rs2275542, rs180096, and rs4149313 polymorphisms in ABCA1 gene and obesity may be associated with low HDL-C disease; (4) the C-C-C-A-A-G, T-C-C-A-A-A, T-C-C-A-A-G, C-C-C-A-A-A, C-T-G-G-A-A, and T-T-C-G-A-A haplotypes were significant between the subjects with normal HDL-C and low HDL-C level (p < 0.05). Conclusions: The differences in serum lipid levels between normal HDL-C and low HDL-C subjects among Kazakhs might partly result from ABCA1 gene polymorphisms; ABCA1 gene polymorphisms may be associated with low HDL-C disease; the low HDL-C disease might partly result from interactions between ABCA1 gene polymorphisms and obesity; the C-C-C-A-A-G, T-C-C-A-A-A, and T-C-C-A-A-G haplotypes may serve as risk factors of low HDL-C disease among Kazakhs, the C-C-C-A-A-A, C-T-G-G-A-A, and T-T-C-G-A-A haplotypes may serve as protective factor of low HDL-C disease among Kazakhs.

Background: Many rare events meta-analyses of randomized controlled trials (RCTs) have lower statistical power, and real-world evidence (RWE) is becoming widely recognized as a valuable source of evidence. The purpose of this study is to investigate methods for including RWE in a rare events meta-analysis of RCTs and the impact on the level of uncertainty around the estimates. Methods: Four methods for the inclusion of RWE in evidence synthesis were investigated by applying them to two previously published rare events meta-analyses: the naïve data synthesis (NDS), the design-adjusted synthesis (DAS), the use of RWE as prior information (RPI), and the three-level hierarchical models (THMs). We gauged the effect of the inclusion of RWE by varying the degree of confidence placed in RWE. Results: This study showed that the inclusion of RWE in a rare events meta-analysis of RCTs could increase the precision of the estimates, but this depended on the method of inclusion and the level of confidence placed in RWE. NDS cannot consider the bias of RWE, and its results may be misleading. DAS resulted in stable estimates for the two examples, regardless of whether we placed high- or low-level confidence in RWE. The results of the RPI approach were sensitive to the confidence level placed in RWE. The THM was effective in allowing for accommodating differences between study types, while it had a conservative result compared with other methods. Conclusion: The inclusion of RWE in a rare events meta-analysis of RCTs could increase the level of certainty of the estimates and enhance the decision-making process. DAS might be appropriate for inclusion of RWE in a rare event meta-analysis of RCTs, but further evaluation in different scenarios of empirical or simulation studies is still warranted.