Simple medical errors could be the third-leading cause of death in the United States. A new study published in “The BMJ” suggests that most mistakes are unobserved in official records. The study out of Johns Hopkins implies that medical errors kill more people than lower respirator diseases like emphysema and bronchitis. That would place the cause right behind heart disease and cancer as the leading causes of death in the U.S. Experts estimate there are more than 250-thousand deaths each year in the U.S. due to medical mistakes.