(Reuters Health) - Just because the flagship hospital gets good marks for patient care doesn’t mean results will be equally good in affiliated hospitals in the same network, a new study finds.

Researchers found variable surgical outcomes across networks associated with hospitals that received the highest rankings from U.S. News & World Report, according to the study published in JAMA Surgery.

The new study shows “you shouldn’t assume that a hospital that is affiliated with a very well known medical center is able to offer the same services,” said the study’s lead author, Dr. Kyle Sheetz, a research fellow at the Center for Healthcare Outcomes and Policy at the University of Michigan in Ann Arbor. “It may, but it may not. You just can’t make that assumption.”

Given the variability within networks, “if patients are within a bigger system, they should realize it’s okay to ask about where and by whom you would have the safest operation,” Sheetz said.

Sheetz and his colleagues analyzed records from 87 hospitals, each tied to one of 16 networks affiliated with a U.S. News & World Report Honor Roll hospital. The data came from Medicare records for surgeries on 143,174 patients between 2005 and 2014.

The researchers focused on outcomes from three significantly different surgeries: colectomy, in which all or part of the colon is removed; coronary artery bypass grafting; and hip replacement.

As it turns out, the Honor Roll hospitals didn’t always have consistently better outcomes than their network affiliates, Sheetz and colleagues found. They tended to have higher complication rates compared to affiliated hospitals: 22 percent versus 18 percent. But this may be because the Honor Roll hospitals were getting the more complicated cases, Sheetz said.

The most telling statistic the researchers gathered may have been “failure to rescue rates,” a measure of how well hospitals cope with surgical complications. To avoid “failure to rescue,” hospital staff need to recognize a complication early “and manage it and prevent the accumulation of other complications,” Sheetz explained. “So it’s ‘rescuing’ that patient.”

Honor Roll hospitals had lower failure to rescue rates than affiliated hospitals: 13 percent versus 15 percent.

The researchers also found fairly wide variation between networks in rates of certain outcomes within the networks. In some networks, differences between affiliated hospitals in failure to rescue rates were as little as 1.1-fold, while in other networks, affiliates varied by as much as 4.9-fold. Complication rates varied in a similar fashion within networks ranging from a 1.1-fold difference to a 4.3-fold difference.

“Just because a hospital is affiliated with a really, really reputable hospital doesn’t mean that it is delivering care on par with that Honor Roll hospital,” Sheetz said. “For a lot of services, that may not matter. For simple care in straightforward patients it may not make a difference. But if you’re having a heart operation or a colon removed for cancer, you want to talk to your doctor about it and ask the surgeon what kind of experience he has.”

The new study “highlights the variability across hospitals and the complex choices that patients face when choosing a hospital or hospital network,” said Tami Minnier, chief quality officer at the University of Pittsburgh Medical Center in Pennsylvania.

But, reassuringly, “the hub hospitals and the majority of affiliated hospitals have results within a fairly tight range,” Minnier, who wasn’t involved in the study, said in an email. “The study does not provide conclusive evidence that affiliates perform worse than their flagship hospitals. Future research should explore the characteristics of hospitals with poorer results.”

SOURCE: bit.ly/2CnhCA2 JAMA Surgery, online March 13, 2019.