Table 9. Meta-analysis grades.

Meta-Analysis Group	Internal Bias	Inconsistency	Indirect	Imprecise	Publication Bias	Large Effect	Dose Response	Confounding Towards Null	Overall
Piped water access (any STH)	Moderate, used help of observations to assess exposure and used adjusted estimates	Yes, I 2 = 98.6%	Nothing serious	Yes, 95% CI includes null	Likely, but unclear due to strong heterogeneity	Nothing strong	Not found	Nothing strong	Very low, due to heterogeneity and wide confidence interval
Piped water access (A. lumbricoides)	Moderate, observational studies but all use adjusted estimates	I 2 = 0%, 95% CI (0%–85%)	Nothing serious	Nothing serious	Likely, but direction suggests slightly more protective effect	Nothing strong	Not found	Nothing strong	Low
Piped water access (T. trichiura)	Moderate, observational studies but all use adjusted estimates	I 2 = 0%, 95% CI (0%–90%)	Nothing serious	Nothing serious	Undetected	Nothing strong	Not found	Nothing strong	Low
Treated water use (any STH)	Moderate, observational studies but all use adjusted estimates	I 2 = 0%, 95% CI (0%–90%)	Nothing serious	Nothing serious	Undetected	Nothing strong	Not found	Nothing strong	Low
Wearing shoes (hookworm)	Moderate, observational studies but all use adjusted estimates	I 2 = 29.7%, 95% CI (0%–73%)	Nothing serious	Nothing serious	Likely	Strong effect evident (OR 0.29)	Not found	Yes, hygiene behaviors overreported	Moderate, due to strong effect size
Wearing shoes (any STH)	Moderate, observational studies but all use adjusted estimates	Yes, I 2 = 74%	Nothing serious	Nothing serious	Likely, but unclear due to strong heterogeneity	Strong effect evident (OR 0.30)	Not found	Yes, hygiene behaviors overreported	Low, upgraded from effect size, downgraded from heterogeneity
Soap use/availability (any STH)	Moderate, observational studies but all use adjusted estimates	I 2 = 20.8%, 95% CI (0%–92%)	Nothing serious	Nothing serious	Undetected	Nothing strong	Not found	Yes, hygiene behaviors overreported	Low
Handwashing before eating (A. lumbricoides)	Moderate, observational studies but all use adjusted estimates	I 2 = 0%, 95% CI (0%–90%)	Nothing serious	Nothing serious	Undetected	Nothing strong	Not found	Yes, hygiene behaviors overreported	Low
Handwashing after defecation (A. lumbricoides)	Moderate, observational studies but all use adjusted estimates	I 2 = 0%, 95% CI (0%–90%)	Nothing serious	Nothing serious	Undetected	Nothing strong	Not found	Yes, hygiene behaviors overreported	Low
Handwashing after defecation (any STH)	Moderate, observational studies but all use adjusted estimates	Yes - I 2 = 88%	Nothing serious	Yes, 95% CI includes null	Undetected	Nothing strong	Not found	Yes, hygiene behaviors overreported	Very low, due to high heterogeneity
Sanitation access (any STH)	Moderate, observational studies but all use adjusted estimates	I 2 = 0%, 95% CI (0%–68%)	Nothing serious	Nothing serious	Undetected	Nothing strong	N/A	Nothing strong	Low
Sanitation access (T. trichiura)	Moderate, observational studies but all use adjusted estimates	I 2 = 19%, 95% CI (0%–62%)	Nothing serious	Nothing serious	Undetected	Nothing strong	N/A	Nothing strong	Low
Sanitation access (A. lumbricoides)	Moderate, observational studies but all use adjusted estimates	I 2 = 28%, 95% CI (0%–70%)	Nothing serious	Nothing serious	Undetected	Nothing strong	N/A	Nothing strong	Low
Sanitation access (hookworm)	Moderately Low, used help of observations to assess exposure and used adjusted estimates	I 2 = 11%, 95% CI (0%–77%)	Nothing serious	Yes, 95% CI includes null	Likely, but direction suggests slightly more protective effect	Nothing strong	N/A	Nothing strong	Very low, due to confidence interval including null