Hospitalization usually gives people a chance to get better, but there are also cases when expectations are not reached or, even worse, people might die while in hospital following medical errors.

According to the fifth annual Patient Safety in American Hospitals Study, from 2004 through 2006, patient safety errors resulted in 238,337 potentially preventable deaths of U.S. Medicare Patients and cost the Medicare program $8.8 billion.

The analysis included data of 41 million Medicare patient records and was released April 8 by HealthGrades, a health care ratings organization.

The analysis found that out of all patients, 3 percent experienced medical errors, such as anesthesia complications, bed sores, failure to rescue (respiratory failure, pulmonary embolism or deep vein thrombosis, sepsis and abdominal wounds that split open after surgery), selected infections due to medical care, as well as many post-operative events. This percentage comes out to about 1.1 million medical errors over the three-year period.

Other findings of the study include: patients who experienced a medical error have a 20 percent chance of dying, the study said; top performing hospitals were 43 percent less likely to experience medical errors; failure to rescue accounted for at least 188,000 lives lost, about 128 deaths for every 1,000 patients; bed sores, failure to rescue and post-operative respiratory failure accounted for 63.4 percent of incidents.

"While many U.S. hospitals have taken extensive action to prevent medical errors, the prevalence of likely preventable patient safety incidents is taking a costly toll on our health care systems -- in both lives and dollars," Dr. Samantha Collier, HealthGrades' chief medical officer and primary author of the study, said in a prepared statement, according to the Washington Post.