We have to recognize that studies that carefully assess the effects of an exposure on health are extremely difficult to carry out correctly without the errors of bias and confounding and, thus, are of variable reliability and validity.

FORBES: How Activism Distorts The Assessment Of Health Risks

These results remained consistent after adjusting for confounding factors and controlling for other potential sources of bias.

FORBES: Acute Kidney Injury Associated With Dual Antihypertensive Therapy And NSAIDs