Technical Note: Acute Myocardial Infarction Readmission

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Technical Note
Acute Myocardial Infarction Readmission

Unit of Analysis:

The unit of analysis is an "Episode of care". An episode of care refers to all contiguous in-patient hospitalizations and same-day surgery visits. For episodes with transfers within or between facilities, transactions were linked regardless of diagnoses. To construct an episode of care a transfer is assumed to have occurred if either of the following conditions is met:

  • Acute care hospitalization or same day surgery visit occurs within 6 hours of discharge from previous acute care hospitalization or same day surgery visit regardless of whether the transfer is coded;
  • Acute care hospitalization or same day surgery visit occurs within 6-12 hours of discharge from previous acute care hospitalization or same day surgery visit and at least one of the hospitalization or visit has coded the transfer.

Denominator (Index Episode)

Inclusion Criteria:

    1. AMI (ICD-10-CA: I21, I22; ICD9/ICD-9CM: 410) is coded as MRDx but not also as a diagnosis type (2); or
    2. Where another diagnosis is coded as MRDx and also as a diagnosis type (2), and a diagnosis of AMI is coded as a type (1), or ; or
    3. Where coronary artery disease (ICD-10-CA: I25.0, I25.1, I25.8, I25.9; ICD9/ICD-9CM: 429.2, 414.0, 414.8, 414.9) is coded as MRDx, AMI as type (1), or ; along with a revascularization procedure (percutaneous coronary intervention(CCI: 1.IJ.50^^, 1.IJ.57.GQ^^, 1.IJ.54.GQ-AZ; CCP: 48.02, 48.03; ICD-9CM: 36.01, 36.02, 36.05) or coronary artery bypass (CCI: 1.IJ.76^^; CCP: 48.1^; ICD-9CM: 36.1^))
  1. Discharge between April 1 and March 3 of the following year (period of case selection ends March 3 to allow for 28 days of follow-up)
  2. Age at admission between 15 and 84 years
  3. Gender recorded as male or female
  4. Admission to an acute care institution
  5. Canadian resident

Exclusion Criteria:

  1. Records with an invalid Health Card Number
  2. Records with an invalid date of birth
  3. Records with an invalid admission date or time
  4. Records with an invalid discharge date or time
  5. Discharged as a death or self sign-out
  6. Any one of the following diagnoses recorded in any position:
    1. Cancer (ICD-9/ICD-9-CM: 140-208, V58.1, V58.0 or ICD-10-CA: C00-C26, C30-C44, C45-C97, Z51.0, Z51.1)
    2. HIV (ICD-9: 042, 043, 044, 795.8 or ICD-9-CM: 042, 043, 044, 795.71, V08 or ICD-10-CA: B24, Z21, R75)
    3. Trauma (ICD-9/ICD-9-CM: E800-848, E880-886, E888, E890-899, E900-910, E913-926, E928, E950-958, E960-968, E970-976, E990-998 or ICD-10-CA: V01-V99, W00-W23, X00-X09, W92-W94, X17, X30, X31, X51, X53, X54, X57, X20-X29, W50-W60, X33-X38, W30, W31, W44, W45, W64-W77, W81-W84, W25-W27, W33-W40, W85-W99, X10-X19, X60-X84, X85-Y09, Y35.0-Y35.4, Y35.6, Y35.7, Y36)

Numerator

Inclusion Criteria:

  1. Readmission within 28 days of discharge after the index episode of care
  2. Emergent or urgent (non-elective) readmission to an acute care hospital
  3. Readmission for any one of the following most responsible diagnoses:
    1. Acute myocardial infarction  (ICD-9/ICD-9-CM: 410 or ICD-10-CA: I21, I22)
    2. Other acute and subacute forms of ischemic heart disease (ICD-9/ICD-9-CM: 411 or ICD-10-CA: I20.0, I23.82, I24)
    3. Old myocardial infarction (ICD-9/ICD-9-CM: 412 or ICD-10-CA: I25.2)
    4. Angina pectoris (ICD-9/ICD-9-CM: 413 or ICD-10-CA: I20.1)
    5. Other forms of chronic ischemic heart disease (ICD-9/ICD-9-CM: 414 or    ICD-10-CA: I25.0, I25.1, I25.3, I25.8, I25.9)
    6. Conduction disorders (ICD-9/ICD-9-CM: 426 or ICD-10-CA: I44, I45)
    7. Cardiac Dysrhythmias (ICD-9/ICD-9-CM: 427 or ICD-10-CA: I46.0, I46.9, I47, I48, I49)
    8. Functional disturbances following cardiac surgery (ICD-9/ICD-9-CM: 429.4 or ICD-10-CA: I97.0, I97.1)
    9. Pneumococcal pneumonia (ICD-9/ICD-9-CM: 481 or ICD-10-CA: J13, J18.1; excluding cases where ICD-9/ICD-9-CM: 496 or ICD-10-CA: J44 is also recorded in any diagnosis position)
    10. Other bacterial pneumonia (ICD-9/ICD-9-CM: 482 or ICD-10-CA: J14, J15.0-J15.6, J15.8, J15.9; excluding cases where ICD-9/ICD-9-CM: 496 or ICD-10-CA: J44 is also recorded in any diagnosis position)
    11. Bronchopneumonia, organism unspecified (ICD-9/ICD-9-CM: 485 or ICD-10-CA: J18.0; excluding cases where ICD-9/ICD-9-CM: 496 or ICD-10-CA: J44 is also recorded in any diagnosis position)
    12. Pneumonia, organism unspecified (ICD-9/ICD-9-CM: 486 or ICD-10-CA: J18.8, J18.9; excluding cases where ICD-9/ICD-9-CM: 496 or ICD-10-CA: J44 is also recorded in any diagnosis position)
    13. Urinary tract infection (ICD-9/ICD-9-CM: 599.0 or ICD-10-CA: N39.0)