Fig 1.
Summary flowchart of literature search.
Table 1.
Characteristics of the included studies.
Table 2.
Risk of bias in observational studies using the Newcastle-Ottawa quality assessment scale.
Table 3.
Risk of bias analysis for intervention studies using cochrane collaborations’ tool.
Fig 2.
The association between soil-transmitted helminth infection or no-deworming on tests of learning.
SD: standard deviation; CI: confidence interval; Std: standard; df: degree of freedom; I2: measure of variability expressed in %. Squares indicate the SMD in each study, with square sizes directly proportional to the weight contribution (%) of each study. Horizontal lines represent 95% confidence intervals (CI). The diamond denotes the pooled standardized mean difference (SMD). The Z test for overall effect indicates deficits for STH infected/non treated vs. uninfected/treated children. The chi-square test indicates heterogeneity is high (P <0.00001, I2 = 66%) warranting use of the random-effects model.
Fig 3.
Galbraith plot analysis to identify outliers among included studies of STH infection and performance in learning tests.
Log SMD: logarithm of standardized mean difference; SE: Standard error. Studies that lie below the– 2 or above the +2 confidence limit are the outliers.
Fig 4.
The association between soil-transmitted helminth infection or no deworming on tests of learning with exclusion of identified outlier investigations.
Diamond denotes the pooled standardized mean difference (SMD). Squares indicate the SMD in each study, with square sizes directly proportional to the weight contribution (%) of each study. Horizontal lines represent 95% confidence intervals (CI). The Z test for overall effect indicates non-significance given that P > 0.05. The chi-square test indicates that heterogeneity (P = 0.12, I2 = 33%) was reduced by outlier treatment. SD: standard deviation; CI: confidence interval; Std: standard; df: degree of freedom; I2: measure of variability expressed in %.
Table 4.
Associations between STH infection/non-treatment and performance in cognitive and educational domains among school-aged children following exclusion of outlier investigations using the Galbraith plot method.
Table 5.
Effect of STH infection/non-treatment on performance in cognitive and educational within strata of study designs, non-outlier investigations and study quality.
Table 6.
Comparison of pooled effects between STH infection and respective outcomes with and without co-prevalent Schistosoma infection.
Table 7.
Summary of the impact of deleting individual studies on the association between STH infection/non-treatment and respective outcomes in overall and sub-group analyses.
Table 8.
Summary of the impact of publication bias on respective outcome domains.