By using an intensive system of training and safety reminders, hospitals in Michigan have eliminated about one in five patient deaths, according to a study in the British Medical Journal.

The pilot program in Michigan started in 2003, an effort to reduce infections among elderly patients in intensive care. In 95 participating hospitals, doctors and staff took part in regular safety meetings and held consultations with infection-prevention experts at Johns Hopkins University. The hospitals also followed formal, five-point checklists of infection control measures – some as simple as remembering to wash hands before a procedure. Other checklist items include frequent adjustments to the position of patients on respirators, and removing catheters that are not absolutely necessary.

“We wanted it to be simple,” said Dr. Allison Lipitz-Snyderman of the Johns Hopkins Bloomberg School of Public Health, the study’s lead author. “These aren’t new ideas. They were already proven to work. They just weren’t disseminated as widely as you’d think.”

Previous studies found the program did reduce infections, but the new analysis goes further, showing it cut the number of actual deaths. While death rates fell in surrounding states as well, the difference was larger in Michigan. There’s no way to calculate the precise number of lives saved, but Dr. Peter Pronovost, the Hopkins physician who led the project, says it’s likely a few thousand Michigan deaths were prevented each year.

Intriguingly, the death rate for elderly ICU patients started to fall during the study period in hospitals throughout the Midwest, not just the Michigan hospitals that implemented the program. After the end of the study period, the death rate continued to drop – even faster than before – in the Michigan hospitals, only.

To Pronovost, this suggests that a shift in hospital culture, rather than specific infection-control measures, was the crucial factor. “I’m convinced that changing the mindset, from thinking these infections were inevitable, to seeing them as preventable, is what made the big difference,” Pronovost told CNN. “Culture takes a while to change.”

Infections acquired in hospitals and other medical settings cause 1.7 million infections and 99,000 deaths each year, according to federal statistics. The Hopkins researchers, the Michigan Health and Hospital Association and the American Hospital Association are now overseeing a project to expand the infection-control program to all 50 states. So far all but three have signed on, with California the big holdout.