BackgroundEvidence of an adverse influence of soil transmitted helminth (STH) infections on cognitive function and educational loss is equivocal. Prior meta-analyses have focused on randomized controlled trials only and have not sufficiently explored the potential for disparate influence of STH infection by cognitive domain. We re-examine the hypothesis that STH infection is associated with cognitive deficit and educational loss using data from all primary epidemiologic studies published between 1992 and 2016.MethodsMedline, Biosis and Web of Science were searched for original studies published in the English language. Cognitive function was defined in four domains (learning, memory, reaction time and innate intelligence) and educational loss in two domains (attendance and scholastic achievement). Pooled effect across studies were calculated as standardized mean differences (SMD) to compare cognitive and educational measures for STH infected/non-dewormed children versus STH uninfected /dewormed children using Review Manager 5.3. Sub-group analyses were implemented by study design, risk of bias (ROB) and co-prevalence of Schistosoma species infection. Influential studies were excluded in sensitivity analysis to examine stability of pooled estimates.FindingsWe included 36 studies of 12,920 children. STH infected/non-dewormed children had small to moderate deficits in three domains—learning, memory and intelligence (SMD: -0.44 to -0.27, P<0.01–0.03) compared to STH-uninfected/dewormed children. There were no differences by infection/treatment status for reaction time, school attendance and scholastic achievement (SMD: -0.26 to -0.16, P = 0.06–0.19). Heterogeneity of the pooled effects in all six domains was high (P<0.01; I2 = 66–99%). Application of outlier treatment reduced heterogeneity in learning domain (P = 0.12; I2 = 33%) and strengthened STH-related associations in all domains but intelligence (SMD: -0.20, P = 0.09). Results varied by study design and ROB. Among experimental intervention studies, there was no association between STH treatment and educational loss/performance in tests of memory, reaction time and innate intelligence (SMD: -0.27 to 0.17, P = 0.18–0.69). Infection-related deficits in learning persisted within design/ROB levels (SMD: -0.37 to -52, P<0.01) except for pre-vs post intervention design (n = 3 studies, SMD = -0.43, P = 0.47). Deficits in memory, reaction time and innate intelligence persisted within observational studies (SMD: -0.23 to -0.38, all P<0.01) and high ROB strata (SMD:-0.37 to -0.83, P = 0.07 to <0.01). Further, in Schistosoma infection co-prevalent settings, associations were generally stronger and statistically robust for STH-related deficits in learning, memory and reaction time tests(SMD:-0.36 to -0.55, P = 0.003–0.02). STH-related deficits in school attendance and scholastic achievement was noted in low (SMD:-0.57, P = 0.05) and high ROB strata respectively.InterpretationWe provide evidence of superior performance in five of six educational and cognitive domains assesse...

Background/Aims: Reported associations of reproductive outcomes (RO) and polycystic ovary syndrome (PCOS) with genotypes of the Ile49Ser and -482A>G polymorphisms in the Anti-Müllerian hormone (AMH) gene and its type II receptor (AMHRII), respectively, have conflicting results. Methods: PubMed, Google Scholar and Science Direct databases were searched for studies that investigated Ile49Ser and -482A>G in RO and PCOS. Using the metaanalytic approach, we estimated risk (odds ratio [OR] with 95% confidence intervals) using standard genetic models. Results: All calculated summary effects were non-significant. Overall associations of Ile49Ser and -482A>G with RO were absent (OR 0.95-0.99, P = 0.76-0.96) but implied increased risk in PCOS (OR 1.07-1.17, P = 0.49-0.55). Where heterogeneity of the pooled ORs were present, its sources were explored using the Galbraith plot. Detection and omission of the outlying studies in both polymorphisms not only erased heterogeneity of the recalculated pooled outcomes but also changed direction of association, where null effects turned to increased risk (Ile49Ser in RO) and increased risk became reduced risk (-482A>G in PCOS). Implications of the Ile49Ser and -482A>G, effects pointed to protection for Caucasians (OR 0.64-0.89, P = 0.36-0.73) in RO and increased risk in PCOS (OR 1.19-1.45, P = 0.28-0.65). Asian effects in RO and PCOS were variable (OR 0.97-1.24, P = 0.58-0.91). Conclusions: In summary, we found no evidence of significant associations of Ile49Ser and -482A>G with RO and PCOS, although contrasting Ile49Ser effects were implied among Caucasians between RO (up to 0.36% reduced risk) and PCOS (up to 1.5-fold increased risk).

This meta-analysis confirmed the protective role of the ApaI polymorphism, however, susceptibility and protective effects of the FokI polymorphism may be ethnic and gender specific.

Inconsistency in the reported associations between the A66G polymorphism in the methionine synthase reductase (MTRR) gene and colorectal cancer (CRC) prompted a meta-analysis, so that we could obtain a more precise estimate. Databases searches of the published literature yielded 20 case–control studies from 17 articles (8,371 cases and 12,574 controls). We calculated pooled odds ratios (ORs) and 95% confidence intervals in three genetic comparisons (A allele, G allele, and A/G genotype). We found no evidence of overall associations between MTRR A66G and CRC risk (OR 0.96–1.05, P = 0.12–0.44). This was materially unchanged when reanalyzed without the Hardy–Weinberg equilibrium (HWE)-deviating studies (OR 0.97–1.06, P = 0.11–0.65). In the A allele comparison, however, outlier treatment generated significant protection (OR 0.91, P = 0.01). Combined removal of the outliers and HWE-deviating studies reflected this summary effect (OR 0.90, P = 0.01) as did the pooled OR from high-quality studies (OR 0.90, P = 0.01). Only the Asian subgroup showed significant (both at P = 0.05) A allele (OR 1.13) and A/G genotype (OR 0.88) associations. In conclusion, post-outlier A allele effects were protective. Our study also suggests ethnic-specific associations with Asian susceptibility and protection in the A allele and A/G genotype comparisons, respectively. Folate status showed no association of this polymorphism with CRC.

This chapter summarizes the progress in Escherichia coli research that used the meta-analysis approach. Using systematic searches for E. coli literature, we tracked meta-analysis publications and analyzed them based on a number of parameters. These included subject/topic (epidemiology, clinical/intervention/prevention and environmental), geographical region (the Americas, Europe and Australasia) and clinical syndrome (enteric, renal, and sepsis/meningitis). These parameters were plotted in terms of time span to obtain a sense of dynamic change or its absence through the years since the turn of the twentieth century. In terms of region, topic and syndrome, highest meta-analysis productivity was attributed to the Americas, clinical/intervention/prevention and enteric, all of which took place in the last 5 years (2011)(2012)(2013)(2014)(2015)(2016). Over the combined time span of 16 years, the Americas significantly dominated meta-analysis outputs when compared to Europe and Australasia (P = 0.003). In conclusion, our findings facilitate awareness of the progress in this field wherein the studied parameters were analyzed for patterns over time and differential rates of publication productivity.