Patients treated for acute MI at high-performing hospitals – those with the best performance on 30-day mortality quality measures assessed by the Centers for Medicare & Medicaid Services – had longer life expectancies than did patients treated at low-performing hospitals, according to a report published online Oct. 6 in the New England Journal of Medicine.

This survival benefit persisted through 17 years of follow-up, said Emily Bucholz, MD , of Boston Children’s Hospital, and her associates.

Until now, researchers didn’t know whether the short-term survival benefit at high-performing hospitals would wane over time, which “would lend support to the theory that these hospitals discharge more patients alive but with higher subsequent mortality.” The results of this secondary analysis of data from a nationally representative cohort study indicate that, instead, the superior quality of care delivered at high-performing hospitals appears to “produce an early benefit that endures over time,” Dr. Bucholz and her associates noted. The investigators assessed long-term life expectancy using data from the Cooperative Cardiovascular Project , which enrolled Medicare beneficiaries aged 65 years and older treated for acute MI in 1994-1996. They focused on 119,735 patients admitted to 1,824 hospitals. They grouped the hospitals according to their case mixes (a measure of patients’ severity of illness) and calculated risk-standardized mortality rates according to CMS criteria.

“We found that patients treated at high-performing hospitals … lived, on average, between 0.74 and 1.14 years longer after acute MI than [did] those treated at low-performing hospitals. These findings were consistent across case-mix strata, which indicates that the relationship between hospital performance and long-term patient outcomes is independent of hospital case mix,” Dr. Bucholz and her associates said (N Engl J Med. 2016 Oct 6. doi: 10.1056/NEJMoa1513223).

These findings show that the early survival advantage achieved by high-performing hospitals is durable, and that “investing in initiatives to improve short-term hospital performance may also improve patient outcomes over the long term,” they added.