Acute Myocardial Infarction (AMI)

---

Acute Myocardial Infarction (AMI) Initial Patient Population

The population of the AMI measure set is identified using 4 data elements:

• ICD-9-CM Principal Diagnosis Code
• Admission Date
• Birthdate
• Discharge Date

Patients admitted to the hospital for inpatient acute care with an ICD-9-CM Principal Diagnosis Code for AMI as defined in Appendix A Table 1.1, a Patient Age (Admission Date minus Birthdate) greater than or equal to 18 years and a Length of Stay (Discharge Date minus Admission Date) less than or equal to 120 days are included in the AMI Initial Patient Population and are eligible to be sampled.

Note: The Joint Commission requires all AMI measures to be collected and submitted as an entire measure set. Measures are specified in the aligned Specifications Manual for National Hospital Inpatient Quality Measures as well as in the Specifications Manual for Joint Commission National Quality Core Measures. The initial population and sampling should be determined for all of a hospital’s cases for the entire set, not at the individual measure level, even though individual measures are defined within the different manuals.

AMI Sample Size Requirements

Hospitals that choose to sample have the option of sampling quarterly or sampling monthly. A hospital may choose to use a larger sample size than is required. Hospitals whose Initial Patient Population size is less than the minimum number of cases per quarter for the measure set cannot sample. Hospitals that have five or fewer AMI discharges (both Medicare and non-Medicare combined) in a quarter are not required to submit AMI patient level data to the QIO Clinical Warehouse and Joint Commission’s Data Warehouse.

Regardless of the option used, hospital samples must be monitored to ensure that sampling procedures consistently produce statistically valid and useful data. Due to exclusions, hospitals selecting sample cases MUST submit AT LEAST the minimum required sample size.

The following sample size tables for each option automatically build in the number of cases needed to obtain the required sample sizes. For information concerning how to perform sampling, refer to the Population and Sampling Specifications section in this manual.

Quarterly Sampling

Hospitals performing quarterly sampling for AMI must ensure that its Initial Patient Population and sample size meet the following conditions:

Quarterly Sample Size
Based on Initial Patient Population for the AMI Measure Set

Hospital's Measures
Average Quarterly Initial Patient Population “Size "N"”	Minimum Required Sample Size "“n"”
>= 1551	311
391 - 1550	20% of the Initial Patient Population
78 -390	78
6 - 77	No sampling; 100% of the Initial Patient Population required
0 - 5	Submission of patient level data is encouraged but not required: -CMS: if submission occurs, 1 – 5 cases of the Initial Patient Population may be submitted -The Joint Commission: if submission occurs, 100% Initial Patient Population required

Monthly Sampling

Hospitals performing monthly sampling for AMI must ensure that its Initial Patient Population and sample size meet the following conditions:

Monthly Sample Size
Based on Initial Patient Population for the AMI Measure Set

Hospital's Measures
Average Monthly Initial Patient Population Size "“N"”	Minimum Required Sample Size “"n"”
>= 516	104
131 -– 515	20% of the Initial Patient Population
26 -– 130	26
< 26	No sampling; 100% of the Initial Patient Population required

Sample Size Examples

• Quarterly sampling:
  • A hospital'’s AMI Initial Patient Population size is 100 patients during the fourth quarter. The required sample size is seen to be a minimum of 78 AMI patients for this quarter.
  • A hospital’'s AMI Initial Patient Population size is 392 patients during the third quarter. The required sample size is 20% of the patient population or 79 cases for the quarter (twenty percent of 392 equals 78.4 rounded to the next highest whole number equals 79).
  • A hospital’'s AMI Initial Patient Population is 4 patients during the first quarter. Submission of patient level data is not required. If the hospital chooses to submit patient level data:
    • CMS: the quarterly sample size would be 1 -– 4 cases for the quarter
    • The Joint Commission: the required quarterly sample size would be 100% of the patient population or 4 cases for the quarter.

• Monthly sampling:
  • A hospital'’s AMI Initial Patient Population size is 516 patients during March. The required sample size is 104 cases from the patient population.
  • A hospital'’s AMI Initial Patient Population size is 502 patients during July. The required sample size is 20% of the patient population or 101 cases for the month (twenty percent of 502 equals 100.4 rounded to the next highest whole number equals 101).