The number of deaths related to patient-safety lapses is nearly double the 98,000 per year cited in the momentous Institute of Medicine report To Err is Human, according to a Health Grades study.

The July Health Grade study says the discrepancy stems from two areas of patient-safety problems that were not included in the IOM study: failure to diagnose and treat a serious medical problem in time, and unexpected death in a low-risk hospitalization.

These two areas (of 16 categories) account for nearly 75% of deaths in a study of 37 million Medicare patient records that showed about 195,000 patients die annually from preventable errors.

Health Grades, based in Lakewood, CO, is a healthcare quality rating and advisory services company.