Health System Measurement Project

Metrics Calculation

Readmission rate is equal to the numerator divided by the denominator, multiplied by 100. Rates are observed and not risk-adjusted for age, gender, or severity.

Numerator: Inpatient readmission for any cause within 30 days of an asthma index admission. The 30-day window is defined from the end of the index admission (discharge date) to the beginning of the first, subsequent admission (admission date). The readmission can occur at any hospital within the same state as the initial admission. Readmissions may be discharged in January to December, include a patient discharge status of “died”, and be transferred.

Denominator: Inpatient index admissions that occurred between January 1 and November 30 with a principal diagnosis of asthma (defined by Clinical Classifications Software 128) that did not die in the hospital.

Estimates are based on a readmission analysis file created from the HCUP State Inpatient Databases from 16 states (AR, CA, FL, GA, HI, LA, MA, MO, NE, NH, NM, NY, SC, TN, UT, and WA) with reliable, synthetic patient identifiers that can be used to track a person across hospitals within a state, while adhering to strict privacy guidelines. These 16 states are geographically dispersed and account for 43 percent of the total U.S. resident population and 42 percent of the total U.S. hospitalizations. Post-stratification on hospital characteristics and patient age was used to develop discharge-level weights for national estimates.