Hospital readmission rate

The hospital readmission rate is the share of patients discharged from a hospital who are admitted again, usually to any hospital, within a defined window after discharge. The most common window is 30 days, though some programs track 7-day, 90-day, or condition-specific rates.

The rate is calculated as readmissions within window / total eligible discharges, and is typically reported per condition — such as heart failure, pneumonia, or hip and knee replacement — because expected readmission risk varies enormously by diagnosis. Programs like the U.S. Hospital Readmissions Reduction Program adjust the raw rate using risk adjustment to account for patient case mix, so hospitals treating sicker populations aren't penalized simply for that difference, and to compare a hospital's actual rate against an expected rate for similar patients elsewhere.

Readmission rate matters as both a quality signal — a high rate can indicate incomplete treatment, poor discharge planning, or inadequate follow-up care — and a financial one, since payers may withhold or reduce payment for readmissions judged preventable. It is a standard input to population health management programs and clinical decision support tools that flag high-risk patients before discharge. A key pitfall is conflating all readmissions with poor care: some are unrelated to the original admission or reflect appropriate, planned follow-up treatment rather than a failure.