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NJ Hospital Care Compare

For Hospitals - Methods of Calculation

This technical page is a resource for hospitals to help them better understand how the data on the N.J. Hospital Care Compare Web site was calculated.

The following DRGs, diagnoses or procedures, based on ICD-9-CM codes, are aggregated to compute the total number for each topic of the study. The following methods are used to identify patient categories and calculate the rates:

  • Postoperative Infections for Surgical Inpatients Rates:

    Numerator (N) = Any inpatient whose stay included having a principal or secondary procedure defined in the ICD-9_CM coding book as being Valid OR Procedure with a secondary diagnosis of infected postoperative seroma (ICD-9-CM diagnosis code 998.51) or other post operative infection (ICD-9-CM diagnosis code 998.59) (excluding inpatients assigned by the grouper to MDC 15).
    Denominator (D) = All inpatients whose stay included having a principal or secondary procedure defined in the ICD-9-CM coding book as being Valid OR Procedure (excluding inpatients assigned by the grouper to MDC 15).

  • Myocardial Infarction Mortality Rates:

    Numerator (N) = All inpatients whose discharge status was death and whose principal diagnosis was myocardial infarction designated as the first episode of care (fifth digit of ICD-9-CM diagnosis equal to 1; the ICD-9-CM codes 410.X1).
    Denominator (D) = All inpatients with a principal diagnosis of myocardial infarction designated as the first episode of care. (Primary diagnosis ICD-9-CM code 410.X1.)
    NOTE: Excludes all transfers in or to an acute care hospital and all discharges to hospice from both the numerator and denominator of this topic, following definitions adopted by QuadraMed from the National Hospital Quality Measures to calculate rates for this indicator.
  • Heart Failure Mortality Rates:

    Numerator (N) = All patients with principal diagnosis of heart failure who die. (ICD-9-CM diagnosis code 402.01, 402.11, 402.91, 404.01, 404.03, 404.11, 404.13, 404.91, 404.93, 428.0, 428.1, 428.20, 428.21, 428.22, 428.23, 428.30, 428.31, 428.32, 428.33, 428.40, 428.41, 428.42, 428.43, 428.9)
    Denominator (D) = All patients with heart failure as principal diagnosis. (See ICD-9-CM code list above.)

  • Pneumonia Mortality Rates:

    Numerator (N) = Number of deaths among cases meeting the inclusion and exclusion rules for the denominator.
    Denominator (D) = All inpatient discharges, age 18 years and older, with principal diagnosis code of pneumonia.
    NOTE: Excludes cases with missing discharge disposition, transferred to another short-term hospital, MDC 14 (pregnancy, child birth and puerperium) and MDC 15 (newborns and other neonates) following the AHRQ Inpatient Quality Indicator definition.
  • Hip Replacement:
    All patients that are grouped using the 3M All Patient Refined (APR) DRG grouper into APR DRG 301 – Hip Joint Replacement.
  • Knee Replacement:
    All patients that are grouped using the 3M All Patient Refined (APR) DRG grouper into APR DRG 302 – Knee Joint Replacement.

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