Why 30 days
Both readmission and mortality measures use a 30-day window that starts on the day of admission or discharge, counted wherever the patient ends up — including at another hospital, or at home. The window is deliberately longer than the hospital stay itself: it captures whether discharge was handled well, whether medications were explained, and whether follow-up was arranged, not just whether the patient survived to the exit.
What risk adjustment does
A hospital treating frail, multi-diagnosis patients will have more deaths and more returns than one treating healthier patients, no matter how good its care. CMS adjusts for age, sex and documented conditions on admission so the published figure estimates the hospital's contribution rather than its patient mix.
The adjustment is good but not complete. It cannot account for poverty, housing instability, whether a patient has anyone at home to help, or whether they can afford the prescription they were discharged with. Hospitals serving poorer communities tend to look worse on readmissions for reasons that start outside the building.
Return days versus return rates
Alongside readmission percentages, CMS reports "excess days in acute care" (EDAC) — days patients spent back in hospital care per 100 discharges compared with expectation. A negative number means fewer days than expected, which is better. It is a more complete picture than a yes/no readmission count, because it distinguishes a brief ER visit from a two-week stay.
The measures in this category
These are the measures CMS publishes in this category, with the national median across all reporting hospitals for context.
| Measure | Better is | National median |
|---|---|---|
| Overall return rate Share of patients who came back to any hospital within 30 days of discharge, across all conditions. | Lower | Not enough hospitals report it |
| Returns after heart attack | Lower | 14.4% |
| Returns after heart failure | Lower | 21.3% |
| Returns after pneumonia | Lower | 17.2% |
| Returns after COPD | Lower | 19.8% |
| Returns after bypass surgery | Lower | 10.9% |
| Returns after hip/knee replacement | Lower | 5.8% |
| Extra days in care — heart attack Days patients spent back in hospital care per 100 discharges, compared with what was expected. A negative number means fewer days than expected — better. | Lower | +4.2 days |
| Extra days in care — heart failure | Lower | +1.3 days |
| Extra days in care — pneumonia | Lower | +3.9 days |
| Returns after outpatient colonoscopy Patients who had to visit a hospital within 7 days of an outpatient colonoscopy. | Lower | 12.9% |
| Admissions after chemotherapy | Lower | 10.7% |
| ER visits after chemotherapy | Lower | 5.3% |
Medians calculated by hospiguide.org from the current CMS release, across hospitals that reported each measure. We use the median rather than the mean because these measures are skewed — a handful of outliers pull an average far from the typical hospital.
Where to go next
Browse hospitals by state to see these measures for a specific hospital, or compare two hospitals side by side. For the official source, see Medicare.gov Care Compare.